A Guide for Field Civil and Structural Engineer

1 BY M.G.ERANDE B.Sc. ENGG (CIVIL)

“Judicious Application of Technical Knowledge and Skill to Suit Site Conditions is the Mantra of Successful Site Engineer”

– MR. M.G. ERANDE COMPILED BY

B.Sc, (Engg.- Civil) F.I.E. India, Chartered Engineer 2

A word from M.G.Erande

This compact book has been prepared based on my field experience and information collected from various hand books and standards of civil engineering. The aim is to provide maximum information which are required by a site engineer in day to day work in a compact form at one place. Please note that matter given is only for guidance and not an authentic document, In any project whatever standards and norms mentioned on drawings and in contract should be followed if any contradiction is found. My heartiest thanks first go to Mr. EKLAVYA SINGH. Managing Director of ESPIC and to all others who have helped in preparing sketches, typing, and have taken pains to go through the text and giving suggestions. As a whole of it the entire work is dedicated to my guru late professor Shri D.G. DHAWALIKAR who constantly encouraged me during my studies in Shri S.G.S.T.I and even during my working in various projects. Your suggestions for corrections and addition are always most welcome.

M.G. ERANDE

(All Rights to reproduce or print of this booklet are reserved with ESPIC and Author) (For Private Circulation only)

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INDEX

1.

PART-1

CIVIL

Page 01 to 56

2.

PART-2

FABRICATION

Page 57 to 127

3.

PART-3

ERECTION

Page 128 to 153

4.

PART-4

SITE- SELECTION

Page 154 to 159

5.

PART- 5

INDUSTRIAL – PROJECTS LAYOUT PLAN

Page 160 to 164

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PART-1 (CIVIL)

1

USE FULL INFORMATION FOR CIVIL ENGINEERING

SOIL INVESTIGATION Once land for a particular project is acquired, immediately this activity starts as beginning of the first step and presence of site engineer is compulsory. Following procedure is to start. 1.

Take a thorough look of the piece of land and mark presence of big, trees, water bodies, bushes etc. which may obstruct with actual construction of various shades for the proposed plant. Mark them on plan of the piece of land.

2.

Mark clearly high tension and low tension lines on plan so that H.O. / Project coordinator may decide about removal / diversification of these lines and necessitate action in advance.

3.

Observe on contoured map general slope and directions of natural drainage of water.

4.

A pit is to be dug at suitable location preferably in the center of 2M square size, the depth of upper most 300mm should be neglected as in this depth natural vegetation and roots of bushes etc. exist. After 300 mm depth take observation of type of soil at every 1meter and store samples, clearly indicating the depth at which it is taken. If a hard stratum is not available up to 4M depth from surface then further deep samples are taken by means of auger by boring. Like wise samples should be collected up to 10M depth taking samples at every 1Meter. If hard strata like morram or rocks are available at say 4 meter depth then there is no need to go further unless desired specifically. This observation has to be confirmed by further digging at 5 to 10 places (depending on size of plot and type of soil) at various places in the plot in order to get an over all idea of underneath ground strata. If water is struck at any depth it should be noted specifically and mentioned in the report. A comprehensive report should be send to H.O. This is an important step since based on this information designer will decide on type of foundation to be provided. In addition following information should be collected and sent to H.O. along with soil investigation report. In case any construction work is going on in neighboring area it should be visited and following information should be communicated to H.O. 1. 2. 3.

Type or name of building / factory. Type of foundation being provided. Whether the excavated depth soil matches with the excavation done in our area.

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4. 5. 6.

Water table in dry season (lowest water table). Water table in rainy season (highest water table). If there is near by sea or river, what is the highest flood level? This information can be collected from local government record and from inhabitants who are residing in the near by area for more than 10 to 15 years.

All the above information should be collected and communicated to H.O. as quickly as possible. This will be the base depending on which further work of design and planning will depend. Delay in sending this information will delay the final completion of the project indirectly. In some projects responsibility of soil investigation is given to a local established laboratory or to a technical institute in the locality. In this case also a site engineer must be present and observe the various procedures and keep soil samples at various depths and send his observations to H.O. even though final decision will be taken based on laboratory findings. It is necessary that site engineer should be well conversant with some soil mechanics terminology given below. Soil is a widely used term in civil engineering project sites. In general sense it is the natural material excavated at site from ground at various depths. Soil is not a single material but it is mixture of clay, sand gravel etc. which are present in various percentage and grains sizes in a mixture. Nature of Soils All types of soils have following properties of varying intensity. 1.

Cohesion Cohesion is the internal molecular attraction which resists rupture or shear of a material. In fine grained soil cohesion is due to water film which holds material together. It is the particular characteristic of the fine-grained materials with particle size below 0.002mm (commonly known as clay). Cohesion decreases with increase in water content, cohesion is greater in well compacted clays.

2.

Internal Friction It is the resistance offered by grains in sliding over each other. It is exhibited pertinently by coarse materials having particle size greater than 0.002mm. The magnitude of internal friction depends mainly on grading, shape, surface texture and degree of compaction, moisture content of the mass and super imposed load to which it is subjected. For the course materials it is usually assumed that the particle size distribution giving greatest dry density has greater internal friction. The strength of non cohesive soils depends solely on internal friction.

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3.

Angle of Internal Friction. The resistance in sliding of grain particles of a soil mass mainly depends upon angle of internal friction. The value of angle of internal friction is independent of the normal pressure but it varies with degree of packing of particles (density). The soils subjected to the higher normal stresses will have lower moisture contents and higher bulk densities at failure than those soils which are subjected to lower normal stresses and thus angle of friction in both cases may be different. The true angle of friction of clay is never 0 and may vary up to 26º.

4.

Capillarity It is the nature of soil due to which it transmits moisture in all directions regardless of any gravitational force. The capillarity action of soil is similar to a piece of cotton cloth with one end immersed in water. The maximum height of capillary rise depends upon the pressure, which forces the water into the soil. This force increases as the soil particle size decreases. The capillary rise in a wet soil may be 4 to 5 times the height of capillary rise in same soil when dry. Following table shows capillary rise in various materials. Sr. No. 1. 2. 3. 4. 5.

Type of Soil Coarse Gravel Coarse Sand Fine Sand & Silt Clays Dry Sand & Pure Clay

Capillary Rise Nil 30 cm 120 cm 90 to 120 cm Negligible

Coarser the grain size faster is the rise of capillarity moisture. 5.

Permeability It is the property of soil due to which water flows through it under the action of (unit) hydraulic gradient. The passage of moisture through the pores of the soil is called percolation. Those soils porous enough for percolation to occur are called pervious or permeable soils. Where as those soils which do not allow percolations are called impervious or impermeable soils

6.

Elasticity It is the property of soil due to which it suffers a reduction in size or volume under a load and regains its original shape and volume when load is removed. The important aspect of this property is that it does not matter as to how many times the load is applied and removed provided the stresses set up in the soil due to application of load is within yield stress. This elastic behavior is typical characteristic of peat.

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7.

Compressibility Due to compressibility present in a particular soil when it is subjected to compression it undergoes significant change in its volume. Gravel, sands and silts are incompressible where as clays are compressible. In moist clay mass when compressed air and or moisture may be expelled and this air and or moisture, which has escaped is not immediately recovered after removal of pressure. In this case decrease in volume per unit increase of pressure is known as “compressibility” of the soil and a measure of the rate at which consolidation proceeds is given by the co-efficient of consolidation of the soil. Compressibility of sand and silt varies with density i.e. denser the material less is the compressibility. For clay the compressibility varies directly with water content i.e. more is the water higher is the compressibility. Clays and other compressible soils are known to swell when over burden is removed.

Density 8.

Bulk Density It is the total wt of the mass including solid particles and effect of voids whether filled with air or water per unit volume i.e. Total wt of soil ----------------------- is termed as Total Val of soil bulk density

9.

Dry Density This is a ratio of the weight of the dry solid matters contained in a unit volume of soils. This means weight of soil parties divided by total volume of soil (determined after the water has been dried without bulk volume changes).

10.

Specific Gravity Of Soil Particles It is known as the ratio of their density to that of water. The specific gravity of soil particles varies from 2.0 to 3.3; generally it is between 2.65 to 2.75. The usual soil weight (void less) is between 2600 to 2700Kg per M3.

11.

Optimum Moisture Content (OMC) It is the specific moisture content in the soil at which specific amount of compaction will produce the maximum dry density, in a particular type of soil. It is expressed as percentage by wt of dry soil. For moist soils there is a percentage of moisture at which the soil will compact to its greatest density which is known as OMC. Following table gives values of OMC for different soils.

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Sr. No. 1. 2. 3. 12.

OMC % 8 to 10 15 15 to 20

Remarks These are general observation for dry soils, variation of moisture content present in soils will change the values

Angle of Repose When a mass or heap of earth (clay, sand, gravel etc. or a mixture of these) is left exposed to whether for some time then its sides will slip and will gradually attain a stable slope without tending to slide further. At this stable state of the mass of a particular material, the angle between the horizontal and this slope is termed the natural angle of repose for that particular material. The table below shows angle of repose for different materials. Sr. No.

Type of Soil

Angle of Repose

1.

Wet clay, wet sand and clay of wet gravel and clay soils not properly drained Dry clay, wet sand, gravel Dry sand, loose earth, dry or wet damp clay, gravel, sand and clay, common soil (properly drained) Sand & clay gravel sand

200

2. 3.

4. 13.

Type of soil Sands & Gravels Silts Clays

270 330 370

Bearing Capacity of Soil The bearing capacity of soil is ultimate load per unit area, which will not disturb the shape of soil or at which load, no sinking or appreciable sinking of foundation will occur, with moisture conditions particularly in clay, sand or mixture of clay & sand remains unaltered. The foundations are never loaded to this ultimate pressure but a factor of safety of 2 to 3 is taken and safe bearing capacity is decided. Thus safe bearing capacity.

=

Ultimate Bearing Capacity ----------------------------------Factor of safety.

Bearing capacity of soil depends upon nature of soil, particle size, mixture of sand, clay, gravel in various proportion, moisture content, hardness of rocks and ingredients etc. and thus it differs from place to place even if some components of ingredients are same. To find out safe bearing capacity tests are to be conducted in field and as well as in laboratory. The most commonly used and dependable field test is PLATE BEARING TEST. In this test a steel plate 16mm thick and min. size of 60cm 2 or a round steel plate of 75cm ø is used. The size of plate can be bigger also. It is placed in a pit bottom at which footing is proposed. The bottom of ground below plate is leveled accurately as much as possible.

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The plate is rotated over the area so that any irregularity over the surface is trimmed off. In case of coarse grained soils where proper leveling is not possible a layer of 6mm thick of fine dry sand is provide and than plate is seated over this sand layer. The plate is loaded by actual super imposition of load or by hydraulic jack against a reaction. Following method of loading is adopted 1. 2.

Load the soil 4 times the proposed designed load and read every 24 hours settlement of the plate in soil, this is done until no settlement occurs. Further load the soil with 50% more load (50% of load applied in 1 st stage). Now read settlement every 48Hrs. until no settlement occurs in 48 Hrs.

The settlement under the test load should not show more than 20mm or increment of settlement under 50% of overload should no exceed 60% of settlement under test load. If the above limitations are not met repeat test with reduced load and in that case the reduced load will be taken for safe bearing capacity of the soil, minimum 2 tests should be conducted preferably with different sizes of plates. It should be clearly understood that soil load test alone is not the only criteria for deciding bearing capacity of the soil. This test must be accompanied by other laboratory tests. How ever in general conditions it gives a fairly accurate idea of bearing capacity of the soil. Following table gives fairly correct idea of SAFE BEARING CAPACITY on common soils. Rocky Soils Sr. No. 1. 2. 3. 4. 5. 6. 7.

Name

Tons / M2

Hard Rock Ordinary Rock Sand Stone Lime Stone Soft Rock Morram (Disintegrated rock) Marl & firm Shale

220 110 130 to 200 100 to 150 20 to 90 20 to 30 50 to 60

Intensity of pressure on rock foundation should at no paint exceed 1/8 of crushing pressure of rock.

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Cohesive Soils Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10 11. 12. 13.

Name of Soil Very stiff boulder clays Hard or stiff clays and sand clays Firm clays and sand clays Ordinary clays Sand & clay mixed or inlayers Red earth Moised clay Soft clays & silts Very soft clays and silts & peat Black cotton soil Alluvial soil Alluvial loam Made up ground (consolidated)

Safe Bearing MT/M2 65 30 to 40 20 20 20 25 to 30 10 Not allowed Not allowed 5 to 10 3 to 9 9 to 10 5

Capacity

Non-Cohesive Soils Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9.

Name Compact gravel or sand well cemented Compact gravel or sand and gravel Loose gravel or sand and gravel Compact coarse sand (confined) Loose coarse sand Compact fine sand (confined) Loose fine sand Sand with clay Kankar

Safe bearing capacity MT/M2 50 to 80 40 to 50 30 40 20 30 10 15 25

Note: 1. 2.

Bearing capacity of soils under long rectangular footing should be taken only 75% of bearing capacity under square footing. The above bearing capacity values are only approximate and actual allowable bearing pressure on soils may differ considerable depending upon existing conditions on a particular site. These can be taken as general guide line. Actual figures are to be taken from various field and laboratory tests.

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General Classification of Soils Field classification on particle size Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Type Boulders Cobbles Pebbles Gravels Sand coarse Sand Medium Fine Sand Coarse Silt Medium Silt Fine Silt Clay

With 90% of Parts Greater But less than than mm equal to mm 200 80 200 2.36 75 2.0 60 0.6 2.0 0.2 0.06 0.06 0.02 0.02 0.06 0.006 0.02 0.002 0.006 0.002

or

Average weights of soils 1. 2. 3. 4. 5. 6.

Earth dry to wet Sand dry to wet Sand and clay Gravel Gravel & sand Silt dry to wet

1600-2400 Kg/M3 1450-2000 Kg/M3 2000 Kg/M3 1450 Kg/M3 1750 Kg/M3 1600-1750 Kg/M3

Testing Piles for Loads Ordinarily 1/3 of the total piles on an area should be tested but in no case less than 2 No. of piles for the entire area should be tested for loads, or the no of piles to be tested should be as per contract condition. When a designer wishes to confirm in advance the load carrying capacity than pile of designed dimension and specifications is castled in the plot (preferably in center) or near center so that it will not interfere with foundations for machines or column footings to be constructed in future and is subjected to load test A suitable platform is build on top of piles which has completed at least 24 hours in case of pre-cast pile and 14 days in case of cast in situ concrete pile. The total test load should be 1.5 times the proposed working load, which should be applied in 4 to 6 increments starting with 50% of the working load. The next increase should be after 12hours when there is no settlement. Final load is allowed to remain at least for 48hours after there is no settlement and which should not exceed 0.3mm in 48hours (total net settlement after deducting the rebound). In case settlement is more the load should be reduced.

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The above procedure is a brief general procedure the detailed procedure is specified by the designer and is to be followed after thorough study. Usually pile testing agencies are there who conduct and record test result and submit their report. During testing site engineer must be present and witness observations and sign the observation/ recordings. Extraction or Pulling Out Test. Piles can be pulled out by (1) a direct pull from a winch in the case of short and easily removable piles (2) By hydraulic jocks acting on a large grip surrounding the pile (3) By an inverted double acting hammer. The pile to be pulled out should be kept constantly lubricated with water to reduce friction of soil. The pulling force is calculated from the frictional resistance of the soil. Safe uplift strength of friction piles in sand, clay or gravel is generally taken half of the safe bearing load. Ultimate Strength of Pile. The ultimate strength of a pile is that load which when applied; the pile begins to show settlement. Alternately the maximum load, which can be carried by a pile, is at which the pile continues to sink without further increase of load. A suitable factor of safety (generally 2 to 3) has to be applied to arrive at the ALLOWABLE LOAD. Following is the requirement as per contract conditions, which has already been followed in various projects where pile foundations have been provided. This can be adopted for other sites also LOAD TEST ON PILES: Individual pile or a group of pile shall be tested as directed by engineer to the required load as specified below: Individual pile Group of piles

1.5 times safe load carrying capacity of pile. No. of piles x 1.5 times safe load carrying capacity of individual pile. LOAD TEST PROCEDURE:

The loading shall be done by reaction from the Kent ledge of adequate capacity for the full test load. Test pit shall be excavated by open excavation through all types of soils and disintegrated rock to required depth. The base of the pit shall be minimum 3m x 3m size with adequate side slopes with provision for shoring dewatering etc. The excavated materials shall be dumped sufficiently away from the edge of the excavation so as not to endanger the stability of pit. After completion of the test the pit shall be back filled as directed by the engineer. The hydraulic jack for transferring the load to the pile shall be of capacity 25% in excess of the test load and shall be provided with calibrated pressure gauge. The contractor shall furnish to the engineer necessary test certificates form approved authority to certify the pressure gauges which are calibrated before putting in to operation. The deflection dial gauges to measure the settlement of pile shall have 0.02mm sensitivity and the reading shall be taken to an accuracy of 0.1mm. The contractor shall include charges for calibration of dial gauges in his rates and shall furnish to the engineer 10

necessary test certificates for each dial gauge from approved authority before putting the dial gauges into operation. Before any load test is performed the contractor shall obtain approval of the set up and the load frame from the engineer. Care shall be taken to ensure that the center of gravity of Kent ledge is on the axis of pile and load applied by jack is co-axial with the pile. The pile cap for the selected pile or pile group to be tested shall be cast of a mix capable of sustaining the test load or preferably of same mix as prescribed for the pile cap, and shall be perfectly level. The pile cap shall be absolutely free from surrounding ground. One M.S. plate of 50mm thick shall be set on the pile cap such that its surface is horizontal and perfectly level. The hydraulic jack shall be inserted between the M.S. plate and the Kent ledge frame. The jack shall be so placed as to transfer the load centrally to the pile. The dial gauges shall rest on diametrically opposite ends of the pile cap and shall be fixed to a datum bar whose ends shall rest upon non-movable supports. The supports for the datum bar with reference to which settlement of the pile would be measured shall be at least 5D away clear from the pile, where D is diameter of the pile. Loading and unloading procedure for conducting the test shall be as per IS 2911 or any other procedure agreed by the engineer. INTERPRETATION The safe allowable load on the pile shall be the least of the following: a) b)

Two third of the final load at which the total settlement attains a value of 12mm. Two third of the final load at which the net settlement increases to 6mm.

No payment shall be made to the contractor for conducting the load test, if the safe allowable load is found to be less than the specified working load and also the pile shall be rejected. RECORDS The contractor shall keep the following records of all the tests and shall obtain counter signature of the engineer. i)

Details of Piles.

a) b) c) d) e) f)

Pile designation / location etc. Date of casting of pile. Cube strength of concrete in the pile. Description of strata at which the pile was founded. Pile test commenced on. Pile test completed on.

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ii)

Details of Instruments used. a) Make and specification of jack, pressure gauge and dial gauge. b) Capacity of jack. c) Calibration of pressure gauge & dial gauge used. d) Design load of pile, description of location and identification mark of the pile. e) The readings for settlement and rebound shall be entered in the following from: iii) Test recordings Time Load Dial-1 Settlement Dial-2 Settlemen Mean Remarks / t/ Settlement / Rebound Rebound Rebound 1 2 3 4 5 6 7 8

Two Sketches sk1 and sk2 are given here for typical arrangement of load test on piles and typical arrangement for tensile load test to pile using hydraulic jacks.

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(BRIEF NOTES ON C.F.A. PILES.) This is a continuous flight auger pile hence it is called C.F.A. pile. This type of piles are being used extensively in UK, U.S.A Gulf countries and other places where there is a problem of low water table and collapse of sides. For these piles codes are still to be made and published officially. In INDIA the use in not known. METHOD As the name suggests operation of drilling and concreting are continuously done. The concrete used is with high water cement ration and it is necessarily pumped in the central hollow pipe of augur from the top. The cutting edges are fixed in a helical shape on the central pipe which is rotated by a drilling rig, the digging head of the auger is fitted with a expandable cap. When auger has reached to required depth concrete is pumped inside the hollow pipe from top and auger is lifted simultaneously without rotation. The pressure of concrete blows off the expandable cap. Stuck material in the fins of cutting blades is removed manually as the auger is lifted above ground. When the boring is filled up to the top, steel reinforcement which is kept ready in advance is inserted in the bore filled with concrete with the help of drilling rig. Post insertion of reinforcement in the bore filled with concrete makes it different from the cast in situ piles which are generally used in INDIA. Reinforcement cages with lengths up to 12 meters are common, greater lengths can be installed with the assistance of cage vibrators. SUITABILITY OF C.F.A. PILES C.F.A. piles are best suited to places where unstable ground conditions and high level of ground water table exist. These piles can be terminated in clays, granular soils, in soft rock or can be taken to hard load bearing strata i.e. bearing type of piles or friction piles due to their continuous operation. C.F.A. PILE SIZE & DEPTH. Diameter wise; - 300 to 900 Ø (i.e.. 12 to 36 inches.) Depth wise: - 18 mater to 21 meter (i.e. 60 to 70 feet) Note: - C.F.A. piles have been installed for more than 30.5 meter (100 feet) in some cases. ADVANTAGES OF C.F.A. PILES. 1)

2) 3)

The construction of piles is without significant vibration or excessive noise being produced. This makes it very useful in urban areas and in unstable soil conditions, high water table areas and environmentally sensitive areas. Since rigs used are very powerful, it saves lot of time of constriction of foundations. When used in large scale the process is economical.

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SOIL CONDITIONS Most of the ground conditions can be penetrated by C.F.A. system as the rig used is very powerful, unstable conditions of ground like sandy or muddy soil filled up area, reclaimed land etc. and water. C.F.A. piles do not require support and piles can be terminated with penetrations into clays granular strata, chalk or soft rocks, with end bearing on hard material. CONSTRUCTION SEQUENCE Following figures give an idea of construction of continuous flight auger piles.

1) 2) 3)

The digging head of the auger is fitted with an expandable cap. The auger is screwed into the ground to the required depth. Concrete is pumped through the hollow stem, blowing off the expendable cap under Pressure. 4) Maintaining positive concrete pressure the auger is withdrawn and the reinforcement is placed into the pile up to the required depth. Following table describes some C.F.A. pile specification and clearance required for C.F.A. piling rig. C.F.A. PILE SPECIFICATION

TYPICAL C.F.A. PILING RIG.

Clearance Diameter Compression from Working Width Mast Height mm. kn. corner mm. mm. mm. 300 600 750 1500 2700 18000 350 1100 750 1500 2700 18000 400 1350 750 1500 2700 18000 500 1700 1000 1500 2700 18000 600 2400 1000 1500 2700 18000 Note :- above figures are as published by m/s SKANSKA who under take design and construction of C.F..A piles and have large fleet of rigs. C.F.A. piles if used in INDIA will save lot of time in construction of foundations for high rise buildings bridges for road and railways. Clearance front mm.

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It is expected that in future INDIAN standard shall be published for C.F.A piles.

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REFERENCE LEVEL The next important step for site engineer is to fix reference level which will be used during all construction work. The reference level is generally taken (i) with reference to existing floor of other units existing in the premises or (ii) with reference to outside road levels or H.F.L (Highest Flood Level) as desired and instructed by H.O. In general proposed floor level i.e. F.F.L. (Finished Floor Level) is marked as 0.00. The reference level should be marked +1.00 or more like +1.5 or +2.00 at 3 or 4 places on permanent existing construction for all future reference. Once cols (Steel or R.C.C.) are constructed this reference level should be transferred permanently on cols. This will be useful during other civil construction as well as mechanical erection. INITIAL GROUND LEVELS After reference level as above is fixed immediately existing plot should be divided in a grid of 1 or 2 meter intervals and existing ground levels should be marked on map of the plot. Special care is to be taken for deep & raised part where additional levels are to be taken. This will be required to work out volume of filling or cutting when area is leveled, 3 copies of such plot drawings are to be made and one copy sent to H.O., one copy to be kept by site engineer and one copy given to the owner. These copies should be duly signed by surveyor, representative of owner and site engineer. It may be highlighted that the contoured map should not be the criteria for calculating either volume of filling or cutting since the ground levels change due to action of whether or man made actions. However contoured map is useful for knowing the general topography of the ground and presence of hillocks or Natural River or ponds etc. in the plot and help in deciding the floor and ground levels for future construction. EXCAVATION Normally excavation drawing is provided by designer and excavation is to be done as per this plan only. At site at which place excavation is to start, following guide lines be kept in mind. Please remember here excavation in one shade of project only is under consideration. After studying excavation plan carefully mark area 1, 2, 3------ etc. in the increasing order of depth to which excavation is to be done. In all cases those foundations, which are deepest should be excavated first, whether it is for column, footing or machine foundation. In case of machine foundations like that of un-coilers, exit & entry accumulators, zinc pot, mill foundation etc. these must be excavated first leaving 3 cols- on both rows from corners of excavation including in between col. If the strata which are encountered are rocky there may not be much problem. But when strata is made of sand, sand and silt, clay and excavation of deeper foundation is done later it may endanger the shallow foundations Again if water table is high or any water stream is struck, the water can be pumped out by providing 2 or more temporary sumps in the corner and water is pumped out during work constantly.

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If large quantity of water is struck and with water sand or silt is also observed in that case stop the excavation immediately and back fill the area with excavated material to a height so that water stops coming. After this cordon the excavation area by providing sheet piling all around. The area covered by sheet piling should be at least 3 meter more in length as well as in width. To make it further clear if excavation area has a length of „a‟ and width of „b‟ then the area covered by sheet piling should be minimum (a+3) meters in length and (b+3) meters in width, after providing sheet piling, further excavation should be started the depth of sheet pile to which it has to go is bottom level of P.C.C. for foundation +3 meters minimum. Proper struts must be used to hold sheet piles in position, other wise sheet pile may it self collapse due to back pressure from soil and water or back pressure from both. The concreting and construction activities in case of deep foundation has to be much faster (day night work should be organized) and all efforts should be made to complete work up to at least 3 to 4 meters in height from P.C.C level. Following is a hint for stopping ground water when met in excess:Fill empty cement bags with a mixture of sand and cement 1:6 ratio and tightly close both ends and keep on the area in a orderly manner. This will put weight on the ground and cement and sand will get hardened, since cement will not flow away with water. The bags may be in one or two layers till water stops coming up or comes in manageable quantity, over this hardened layer P.C.C. can be laid and further construction can proceed. In filling bags with sand and cement even sweeping cement can be used if available. STACKING OF EXCAVATED EARTH This is an important factor often neglected at site and causes lot of problems. The excavated material should be staked minimum 6-meters away from excavated edges. It will be observed that generally it is stacked with in 1 to 3 meters which exerts excess pressure and help in slippage at a faster rate which causes many problems during further excavation and further construction. DEWATERING FROM DEEP EXCAVATION First of all keep sufficient no of dewatering pumps ready prior to starting excavation particularly in areas where water is likely to be met during excavation. Secondly where dewatering is going on ensure that water is thrown away from excavation area in such a way that it does not stagnate in one place but immediately flows away. Never throw water near excavated portion or on the excavated material. The obvious reason is, first that this water will increase weight of excavated material and which in turn increase the rate of side slips. Secondly this water will percolate through ground and come back in the excavated pit making the effort of dewatering futile.

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THE GOLDEN RULE FOR EXCAVATION “Excavate from deepest portion to shallow portion” THE GOLDEN RULE OF SURVEY Always proceed from WHOLE TO PART and never follow reverse. SOME THUMB RULES FOR EXCAVATION & FILLING 1) 2) 3)

Excavation in soft to moderately hard (morram type) one laborer‟s capacity to dig. In 8 hrs. Working is 2 to 2.5 m3 up to a depth of 2 meter and lead of 3 meter. One laborer‟s capacity in 8 hours filling including ramming and watering in 150mm layers, can be assumed 5 to 6m3 Excavation in soft rock & hard rock per man 8 hours working. Soft Rock 0.5m3 Hard Rock 0.25m3 Brick work and Concrete.

1.

Cement Mortars Mortars of various proportions are used for plastering and brick work. Quantities bellows are dry cement and sand required for one cubic meter of WET MORTOR Sr. No. 1. 2. 3. 4. 5. 6. 7. 8.

2.

Mix. Ratio Cement & Cement Sand Kg. 1:1 1020 1:2 680 1:3 510 1:4 380 1:5 310 1:6 250 1:7 220 1:8 200

Sand M3 Remarks 0.71 0.95 1.05 1.05 1.05 1.05 1.05 1.05

These quantities of cements and sand are including wastage and as such no extra quantities are to be taken for wastage

Brick Aggregate In Bangladesh and eastern parts of India where stone aggregate availability is scares and costly it is common practice to use brick aggregate made by breaking of slightly over burnt bricks manually or by brick crushers. Brick aggregate is used at places where strength is not major criteria from design point of view, the example will be P.C.C. below R.C.C., filling of gaps etc. How ever in local buildings brick aggregate is used even for slab & beams of residential buildings. But columns. Footings, beams, floor and roof slabs of factory buildings should be concreted by using stone aggregates only. 1 M3 of brick aggregate is obtained from breaking of 420 to 430 No. of 9” size brick or 450 to 460 No. of Indian standard bricks. 1 M3 of brick aggregate

=

430 No. of 9” Brick. 450 No. of I.S. Brick.

=

20

When brick aggregate is used in R.C.C. following factors are recommended by P.N. Khannas hand book of civil engineering. Extracts from P. 8 /122. “The following stresses may be adopted in brick aggregate reinforced concrete for design calculations”. 1. 2. 3. 4. 5. 6. 7. 8.

Compressive stress for 1:2:4 concrete Tensile stress in steel untested Shear stress „m‟ modular ratio „kd‟- neutral axis „jd‟ (leaver arm of resisting moment) „p‟ (reinforcement)% „Q‟ (Moment factor) = BM

40 Kg/ Cm2 1200 Kg/ Cm2 3 Kg/ Cm2 20 0.400d 0.867 d 0.0067bd 7.136bd2

“The proportion of voids can be estimated by filling a measure with the aggregate and then pouring water until the water is level with the top of aggregate, the ratio of the volume of water added to the volume of aggregate is that of the volume of voids to that of the aggregate. “ Cement Concrete Important information about cement. 1 Bag of cement of any grade wt. Of cement = Vol. Of cement = 3 Wt. Of 1M of cement =

50Kg. 34.72 Say 35 liters = 0.035M3 3 1440 Kg/ m net. Wt. Of sack or bag is excluded.

Equivalent size of a box for 1 bag (50kg. of cement) is 40cmx 35 cm x 25 cm 400 x 350 x 250 dimensions in mm Quantities of cement stone aggregate, sand, (all dry) for 1M3 of wet volume of concrete for various ratios is as per following tabel, when mixing is done in a mixer machine. Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Nominal Mix 1:1:2 1: 1.5:3 1:2:3 1:2:4 1:2:5.5 1:3:6 1:4:8 1:5:10 1:6:12 1:6:18

Cement Kg. 580 390 380 310 270 210 160 130 110 80

Dry Sand Stone Aggregate Remarks. Vol. M3 12 to 20mm 0.4 0.8 0.42 0.84 0.54 0.81 Cement should 0.45 0.90 always be weighed. 0.46 0.92 Equivalent size of box for 1 bag (50Kg) 0.46 0.92 of cement is 40CM x 0.47 0.94 35CM x 25CM 0.48 0.96 0.49 0.98 0.35 1.00 21

Water cement ratio It is a ratio of wt. of water added to 50Kg of cement (1 bag of cement). Since wt. of water is 1 Kg per litter it will be volume of water in liters added to 50Kg or 1 bag of cement. Generally water cement ratio varies from 0.4 to 0.55 depending upon dryness of coarse and fine aggregates. Percentage of Voids in Sand and Aggregate Sr. Material No. 1. Fine sand moist 2. Coarse sand moist 3. Coarse & fine sand mixed moist (ordinary sand) 4. Coarse & fine sand mixed dry. 5. Gravel 6. Gravel & sand mixed 7. Ballast 20mm and under with 6% coarse sand 8. Broken stones 25mm and under 9. Broken stones 40mm and under 10. Broken stones 50mm and under most small stones screened out 11. Same as below 63mm & below 12. Brick ballast

Voids % average 43 35 38 30 27 to 37 22 to 25 33 46 41 45 41 35-40

Weight in kg per cubic meter for aggregate and sand and other materials used in civil engineering works 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Brick aggregate Stone aggregate Sand dry & clean River sand dry Wet sand Cement mortar Cement concrete plain Reinforcement cement concrete with 2 to 5% of steel. Common bricks hand made Machine made Mild steel Stone masonry mortar rubble Stone masonry random rubble Water clean & potable

930-1260 2250 1450-1600 1840 1760-2000 2080 2300 2500-2700 1600-2700 2400 7850 2500 2100 to 2200 1000

22

Reinforced concrete short theory Plain concrete has tensile strength which is 1/10 of its strength in compression. A plain beam of concrete when loaded will fail at bottom while top portion can still take ten times the stress. In order to over come above weakness of concrete steel reinforcement bars are introduced at the bottom and the same size of beam of only concrete can be made 10 times stronger. Volume for volume steel costs 60 to 70 times to the cost of concrete. For the same cross section steel resists about 280 times in tension and 28 times in compression. Considering above combination steel and concrete i.e. reinforced cement concrete is used for economy. In R.C.C. design two methods are used. 1. 2.

Working stress or elastic method. Load factor or ultimate load method.

Both methods give some what different type of results. Most commonly used is working stress method of design. Factor of Safety. It is the relation between ultimate strength at failure and permissible stress.

Factor of Safety

=

Ultimate Stress at Failure. ---------------------------------Permissible Stress

Factor of safety is 3 for concrete based on cube test crushing strength. Factor of safety for steel adopted is 2 for steel which is based on

=

Yield Stress ------------------Permissible stress

Modular Ratio It is the relation between modulus of elasticity of reinforcing steel and modulus of elasticity of concrete. It is represented by notation „m‟. Since there is no relative movement between concrete and steel in reinforced concrete, the elongation or contraction of both steel and concrete is same. This means that modular ration „m‟ will vary with change in modulus of elasticity of either or both steel and concrete.

m (modular ratio)

=

Modulus of Elasticity of Steel. ---------------------------------------= Modulus of Elasticity of Concrete

Stress in Steel. -------------------Stress in Concrete

The modulus of elasticity of steel is taken constant value of 200000N/mm 2 but the modulus of elasticity of concrete is most variable and changes with strength of a particular concrete. The modulus ratio as specified in Indian standard is 2800 / 3fc where fc is maximum permissible compressive stress due to bending is concrete in kg/sq. Cm. The modular ratio for various grades is as given in the table on next page.

23

Sr. No. 1. 2. 3. 4.

Grades of Concrete M100 M150 M200 M250

Ratio 1:3:6 1:2:4 1:1.5:3 1:1:2

Modular Ratio 31 18.7 13.3 11

Grades of Concrete : Concrete is of 2 grades 1. Ordinary Concrete 2. Controlled Ordinary Concrete :In ordinary concrete proportions of cement, sand and aggregate are arbitrarily mentioned like those mentioned in above table. Controlled concrete (Design Mix) : In controlled concrete proportions of ingredients cement, sand and aggregate are decided after conducting several tests in laboratory. A controlled concrete gives 25% higher strength from the arbitrary proportion. The proportions of ingredients in controlled concrete are slightly different from the proportions in ordinary concrete. Concrete consolidated by vibrations gives 10% higher strength than manually consolidated concrete, hence proper consolidation by use of mechanical vibrator is always insisted in construction. Site Tests for Concrete: 1. 2. 3.

Workability test. Slump Test. Cube / Cylinder crushing test.

1.

Workability Test : It is carried out for proper specified proportioning of fine and coarse aggregates and water. For this size of boxes for feeding coarse and fine aggregates to mixer machines are measured by site engineer and standard can of 5,10 or 20 litters for feeding water to mixer is checked.

2.

Slump Test : Slump cone test is used to decide volume of water to be adjusted as per site and whether conditions and wetness or dryness of aggregate. The apparatus is a steel mould of frustum of cone shape. The top diameter is 10 cm and bottom diameter meter 20 cm and vertical height 30 cm, fixed with foot pieces at bottom and handle on sides.

24

The cone is placed on smooth non-absorbent surface, which may be a steel plate. Freshly mixed concrete is placed in the cone in 4 layers one after the other each layer is compacted 25 times with a bullet pointed rod of 16 mm, diameter and 600mm long. When filled up to top and leveled to top surface, mould is immediately with-drawn with the help of handles and the slump or subsidence of the concrete is measured from a straight edge held across to top of concrete lightly. Slump is the vertical settlement of concrete after removal of steel mould. The required limits of slump are given by the designer and are mentioned in the drawing. i. ii. iii.

If slump value obtained is with in required limit, water added is correct. If slump value obtained is less than required limit, more water is to be added. If slump value obtained is more than the required limit, it indicates more water is being added and water quantity should be reduced and adjusted.

Recommended Values for Slump Sr. No. 1. 2. 3.

Type of Work

Slump Value in mm With mech. Manual Vibrations Consolidation Mass concrete large sections, roads ect. 10 to 25 50 to 75 Foundations footings, substructure walls and 26 to 50 40 to 115 other heavy sections Thin sections such as slabs, beams, columns 40 to 80 100 to 175 with congested reinforcement.

Permissible Working or Design Stress for Cement Concrete Sr. Grade of Ratio No. Concrete

1.

2.

3.

4.

M100 Or M10 M150 Or M15 M200 Or M20 M250 Or M25

1:3:6

30Kg/Cm2 25 Kg/Cm2

In Bond Bearing Direct Average pressure on Tensile for Full area of Stress Anchorage concrete 4 Kg/Cm2 25 Kg/Cm2 12Kg/Cm2

1:2:4

3.0N/mm2 2.5 N/mm2 50Kg/Cm2 40 Kg/Cm2

0.4 N/mm2 6 Kg/Cm2

2.5N/mm2 1.2N/mm2 37.5Kg/Cm2 20Kg/Cm2

5.0N/mm2 4.0 N/mm2 1:1.5:3 70Kg/Cm2 50 Kg/Cm2

0.6 N/mm2 8 Kg/Cm2

3.75N/mm2 50 Kg/Cm2

7.0N/mm2 5.0 N/mm2 85Kg/Cm2 60 Kg/Cm2

0.8 N/mm2 9 Kg/Cm2

5N/mm2 2.8N/mm2 62.5Kg/Cm2 32Kg/Cm2

8.5N/mm2

0.9 N/mm2

6.25N/mm2

1:1:2

In Compression Due to Direct Bending Compression

6.0 N/mm2

2.0N/mm2 28Kg/Cm2

3.2N/mm2

Concrete mixes are indicated like M100 or M10, M150 or M15, M200 or M20, M250 or M25 both type of nomenclatures are commonly used. But strength is same.

25

Explanation 1.

2. 3. 4.

The table is based on IS Code 456 published in 1964 and 1987. in the code in 1964 metric units were used. While is 1987 code SI units have been used and the values are expressed in N/mm2 (10Kg/cm2 = 1 N/mm2) M in above table refers to grade of concrete and number refers to the specified 28 days compressive strength of the mixed in Kg/cm2 or N/mm2 Grades lower than 1:2:4 are not to be used normally for reinforced concrete works. In case of high yield strength deformed bars are used the permissible bond stress be increased by 40%. For bars in compression, the values of bond stress for bars in tension shall be increased by 25%.

Compressive strength for concrete Crushing strength tests are made on 15cm 3 the maximum grade of aggregate should not be more than 40mm. If the aggregate size is less than 20mm the cube size need be only 10cm. If aggregate size is more than 40mm the cube size can be increased. Normally the cube size should be 4times the maximum size of the aggregate. When cylinders are used the size of the cylinder size is 15cm diameters and 30cm high. The compressive strength is 0.8 times compressive strength specified for 15cm cubes. The permissible working strength is adopted as 1/3 of its cube crushing strength at 28 days. Normally 7 days tests of cubes / cylinder for crushing strength are used in order to asses strength of concrete pending results of 28days strength of crushing test. Concrete is deemed to be satisfactory if 7 days crushing strength is at least 2/3 of the required test strength at 28 days. For 3 days crushing strength of concrete cubes should come about 1/3 of crushing strength required for 28 days). However it should be clearly understood that governing factor for acceptability 28 days strength is only considered 3 days and 7 days crushing strength test though important but are only guiding factors. Method of cube filling for crushing strength of concrete. The concrete cubes are filled in 3 layers and each layer is consolidated by giving 25strokes with 16 MS rod bullet pointed and finished on level. The cube sides are opened after 24 hours and are gently placed in a water tank. For each testing 6 Nos. of cubes are taken and date of casting and location of concreting is written on top surface of each cube. Out of these 3 cubes are tested for crushing strength after 7 days. If 7 days test gives result 2/3 of strength required after 28 days further testing is not required. If 7 days test results are less than required then in that case balance 3 cubes are kept in water for 28 days and tested if results are OK. The concrete is acceptable.

26

Guide lines for no of samples to be taken. Quantity of Concrete in the No of samples work in M3 1. 1-5 1 2. 6-15 2 3. 16-30 3 4. 31-50 4 5. 51 & above 4 plus 1 additional sample for each 50M3 or part there of Note : for each sample means 6 cubes. 3 for 7 days test and 3 for 28 days. Sr. No.

Test strength of sample. The test strength of each sample shall be average of the strength of 3 specimens. The individual variation should not be more than 15% of the average. Required Crushing Strength of Test Cubes. Sr. No.

Concrete mix Ratio

7 Days Strength Kg/cm2

1. 2. 3. 4. 5. 6. 7.

M100 M150 M200 M250 M300 M350 M400

70 100 135 170 200 235 270

28 Days Kg/cm2 100 150 200 250 300 350 400

Strength

Density of Concrete Generally less attention is paid o this factor. This can be easily worked out if concrete cubes are weighed before they are subjected to crushing for finding crushing strength. For finding out density average weight of 3 or 6 cubes should be taken. Average wt of cube in kg. Density of concrete = -----------------------------------Volume of cube in M3 The average density with use of stone chips in concrete. Should be 2200-2300 kg/M3 the average density with brick aggregate should be between 1800-1900 kg/M3. More density indicates soundness of concrete. If density is less it indicates that quality of stones used for making aggregate is not up to the mark.

27

Opening of Shuttering in Various R.C.C. Structures. In normal circumstances and where ordinary Portland cement (OPC) is used form work or shuttering can be opened or removed after expiry of the following periods. Sr. Type of Work No. 1. Vertical faces of walls, columns, beams and vertical faces of all R.C.C. structures 2. Slabs (with props left under intact) 3. Beams softs (with props left under intact) 4. Removal of props under slabs a. Spanning up to 4.5M b. Spanning over 4.5M 5. Removal of props under beams and arches a. Spanning up to 6M b. Spanning over 6M

Period After which shuttering can be removed 24 to 48 hours as decided by Engineer In charge 3 Days 7 Days. 7 Days 14 Days

14 Days 21 Days

Form Work Deviations Following deviations in shape, size etc. from dimensions shown in drawing. Can be accepted. a. Deviation from specified dimensions of -6mm Cross section of columns & beams +12mm b. Deviation from dimensions of footing I Dimensions In Plan

-12mm, +50mm Ii .Eccentricity 0.02 the width of the footing in the direction of deviation but not more than 50mm iii. Thickness 0.05 times the Specified thickness. Note: The above tolerances apply to concrete dimensions only and not to positioning of vertical reinforcement steel or dowels. Curing Period for concrete 1.

Moist Curing. All exposed surfaces of concrete shall be kept continuously in a damp or wet condition by ponding or by covering with a layer of sacking, canvas, hessian or similar materials and kept constantly wet for at least 7 days from the date of placing of concrete.

2.

Membranes Curing Approved curing compounds may be used in lieu of moist curing with the permission of the engineer in charge such compounds shall be applied to all exposed surfaces of the concrete as soon as possible after the concrete has set.

28

Steel Reinforcement Tor Steel is generally used as reinforcement bar. Care should be taken to ensure that Tor Steel bar is not damaged during straightening or giving bends as per drawing. Some steel reinforcement breaks during above process. This indicates that bars are hard and most probably carbon percentage in steel is more, such bars sample should be sent for chemical analysis. 3 Nos. of samples at random from unused rods should be selected. The lot of reinforcement bar should not be used till OK report is obtained. Placing and Binding of Reinforcement Bars. Bars should be placed as per drawing and every cross should be binded by binding wires tightly. Cross-bars should not be tack welded unless permitted by engineer in charge. The reinforcement bars should be placed with in following limits. a. b.

For effective depth up to 200mm or less For effective depth above 200mm or more

10mm 15mm

The total no of bars should however be as per drawing, and should in no case be reduced. The Cover : The cover shall in no case be reduced by more than 1/3 of specified cover or 5mm, which ever is less. Cover Blocks The cover blocks are very important for maintaining specified cover. Generally 50mm, 40mm, 25mm and 20mm covers are provided by designers for different type of R.C.C. construction. Concrete blocks with 1:4 mortars (cemented and sand) with one binding wire inserted should be casted in at least 15days in advance and kept in water for curing and used as per requirement. 300 to 500 nos. of each may be kept ready and further cover blocks be casted as per consumption in work. Welded Joints in Reinforcement Rods. Generally welded joints should be avoided in R.C.C. and lap joints as per design should be provided. Welded joints should be used only in extreme cases. Minimum lap up to 16mm ø rods should be 200mm and welded on 2 sides properly. Above 16mm ø, a lap length of 250mm may be kept and welded properly on both sides. PERMISSIBLE DESIGN STRESSES IN TOR STEEL. In N/mm2 Sr. Type of stress No. in steel and deformed bars 1. Tension a. Up to and including 20mm b. Over 20mm 2.

Mild Steel bars Medium Tensile Steel or Deformed and deformed Deformed Medium Tensile bars as per bars Steel bars. FE415 140 N/mm2 130

"

Compression in 130 Col Bars

"

Half the guaranteed stress max up to 190 Half the guaranteed stress max up to 190 130

yield 230 N/mm2 yield 230

"

190

"

29

Note:Compression bars in a slab are beam when the compressive resistance of the concrete is taken into account the permissible stress in compression in all types of is taken as below. Permissible stress in surrounding concrete x 1.5 times the modular ratio or permissible compressive stress for col. Bars (which ever is less). NOMINAL SIZE AREA AND WT. PER METE OF DEFORMED STEEL (RIBBED BARS) Nominal Size mm 6 8 10 12 16 18 20 22 25 28 32

Cross Sect. Area mm2 28.3 50.3 78.6 113.1 201.2 254.6 314.3 380.3 491.1 616.0 804.6

Wt/ Meter kg. 0.222 0.395 0.617 0.888 1.58 2.00 2.47 2.98 3.85 4.83 6.31

Precaution Heavily rusted, pitted and corroded rods should not be allowed to be used in work. However slightly rusted bars can be used after cleaning and removing rust by wire brush. PLACEMENT OF REINFORCEMENT RODS IN COL. FOUNDATIONS Different views are expressed as to which rods should be placed at bottom i.e. either longitudinal or cross (width wise). This point is always raised at site. To find out correct answer to above quarry following line of thinking is to be followed to come to a correct conclusion. Foundation in plan is either square shape or rectangular shape. Square shape a. a.

a.

a. Bottom reinforcement can be 1. Same ø for both ways. 2. One thick e.g. 20 mm and other 16mm.(for exmple) 3. When both are same ø any way it can be placed. 4. When different ø of rods are used always put higher ø rods at bottom and less ø rods on top as below. 16 ø rods

20 ø. Rods 30

Rectangular shape When footing sides are of different length as below

Considering axial load from col. P is down words and earth pressure will be up wards the overhanging part „X‟ of foundation will act. as reverse cantilever with maximum tension on bottom. Since main reinforcement has to take this tension this reinforcement should be below. If you consider cross section along „a‟ the over hang portion will be „Y‟ but since „X‟ bigger than „Y tension produced along „X‟ will always be bigger than the tension produced along „Y‟. Again this concludes that reinforcement rods along direction „b‟ should be placed at bottom and should be thicker rods. Summarizing above explanation as a thumb rule always place thicker ø rods at bottom along length. In case of discrepancy in drawing i.e. reinforcement ø along shorter side is shown of higher ø and along longer side shorter ø. such problem should be referred to H.O. / designer and after getting proper clarification reinforcement should be placed accordingly. Brick Work Materials and labour required for 1M3 of brick work on an average including wastage is as below Qty. = Bricks = Cement Mortar (wet)=

1M3 of Brickwork 500 Nos. (for both IS bricks and 9” size bricks) average. 0.23M3 for IS Brick. 0.25M3 for 9” Brick.

Quantities of cement and send required for 1M3 of brick work. Mortar Proportion

1:2

Cement in Kg. Sand in cum

156 0.22

Cement in Kg. Sand in Cum

170 0.238

1:3 1:4 1:5 1:6 For IS Bricks wet Mortar qty. = 0.23M3 117 87 71 58 0.243 0.243 0.243 0.243 For 9” Bricks wet Mortar Qty. – 0.25cum 128 95 78 63 0.275 0.275 0.275 0.275

1:7 51 0.243 55 0.275 31

For half brickwork mortar will be 2.5 cum for IS bricks and 2.4 cum for 9” bricks per 100 sq. m of construction Labour (approximate) per M3 of brick work. Mason Unskilled labour

-

1 No. 1 No.

Stone Masonry. Per cubic meter of finished work. Type Boulder filling dry hand packed as in pitching Un coursed random rubble walling laid dry is superstructures.

Stones 1.05 cum 1.20 cum

Mason 1/3 1/2

Labour 1/3 1

Stone Masonry in Wet Mortar Quantities and labour per cum of work. Sr. Type No. 1. Un Coursed random rubble walling laid in mortar in super structure 2. Coursed rubble walling laid in mortar in super structure 3. Ashlar masonry in super structure

Stones M3 1.20

Mortar Wet M3 0.3 to 0.35

Mason Nos. 1.5

labour Nos. 2

1.25

0.30

1.5

2

1.30

0.20

3

3

If ashlar masonry in super structure is done in 1:6 mortar with pointing in cement mortar 1:2, quantity of cement required will be 54kg. Note:- In above quantities of stones are measured in loose stack. Partition Walls (Brick or Concrete Blocks) 1.

Walls with adequate lateral restraint at both ends but not at the top: a.

b.

c.

The panels may be of any height provided the length does not exceed 40 times the thickness: Or. The panel may be of any length provided the height does not exceed 15 times the thickness (that is, it may be considered as a free standing wall): Or Where the length of the panel is over 40 times and less than 60 times the thickness, the height plus twice the length may not exceed 135 times the thickness.

32

2.

Wall with adequate lateral restraint at both ends and at the top: a.

b.

c.

3.

The panel may be of any height provided the length does not exceed 40 times the thickness: Or. The panel may be of any length provided the height does not exceed 30 times the thickness: Or. Where the length of the panel is over 40 times and less than 110 times the thickness, the length plus three times the height should not exceed 200 times the thickness.

When walls have adequate lateral restraint at the top but not at the ends, the panel may be of any length provided the height does not exceed 30 times the thickness. Note: Strength of bricks used in partition walls should not be less than 3.5 N/mm2 or the strength of masonry units used in adjoining masonry, whichever is less. Grade of mortar should not be leaner than M2 (1:6).

Flooring 1.

Brick flooring per 10 Sq. meter with 9” bricks laid flat for 10 sq. m of flooring of depth 4.5” over 12mm thick mortar Bricks = 380 Nos. Mortar (wet) = 0.28cum for 1:4 cement mortar 110 kg cement + 0.28 cu m sand. 1:6 cement mortar 70 kg cement + 0.28 cu m sand. Labour mason = 1 No. Un skilled labour = 2 Nos.

2.

Brick flooring per 10 Sq. m with IS Bricks laid flat (10 cm depth) over 12mm thick mortar bed. Bricks = 500 Nos. Mortar wet = 0.30M3 for 1:4 cement mortar 115kg cement+0.3cu m sand 1:6 cement mortar 75kg cement + 0.3 cu m sand. Labour mason = 1 No. Un skilled labour = 2 Nos.

3.

Brick flooring per 10 Sq. meters with 9” bricks laid on edge (4.5” depth) over 12mm thick mortar Bricks = 570 Nos. Mortar Wet = 0.39M3 1:4 cement mortar – 150 kg cement + 0.39 cu m sand. 1:6 cement mortar – 100 kg cement + 0.39 cu m sand. Labour mason = 1 No. Un skilled labour = 1 No. 33

Concrete flooring 1.

25mm thick cement concrete 1:2:4 finished with floating coat of neat cement per 10 sq. m. Cement - 102 Kg (80 Kg for flooring + 22 kg for floating) Sand - 0.12 cu m Stone aggregate – 0.24 cu m of 12.5mm nominal size aggregate for 40mm thickness. If thickness of floor is more than 40 mm use 20 mm size aggregate. Labour mason Un skilled labour

2.

= =

1 No. 1 No.

25mm thick cement concrete 1:1.5:3 and other things same as in (1) Cement – 122 Kg (100kg for concrete + 22kg for floating) Sand – 0.11 cum. Stone – 0.22 cu m: - 12.5 mm nominal size Aggregate Labour – same as in (1) For 40mm and above thickness of floor use 20mm nominal size of aggregate.

3.

40mm thick cement concrete 1:3:6 with 12mm thick wearing coat on top, (fine grit 1:2) per 10 sq. m. a.

For bottom layer Cement: 85 Kg. Sand: 0.18 Cum Stone: - 0.36 cum (12mm nominal size) Aggregate

b.

For top layer Cement: 85 Kg. Stone aggregate: 0.12 cu m (3mm to 6mm size). If pointing is done add for pointing, quantities as given under heading “POINTING‟. Pointing On brick walls for 100 sq. m in cement mortar 1: 3 Wet mortar Cement Sand

= = =

0.31 cu m. 1.55 Kg. 0.32 cu m.

Labour (including racking joints and watering) Flush pointing Mason = 10 Unskilled labour = 5 34

Ruled Pointing Mason Unskilled labour

= =

12 5

On Stone Walls 1.

Flush or ruled pointing on random rubble walls for 100 sq. m area. Wet mortar – 0.60 cu. M. In 1:3 cement mortar Cement – 306 kg. Sand – 0.630 cu m.

2.

Same on ashlar rubble walls. Wet mortar In 1:3 cement mortar: - 0.23 cu m. Cement – 117 kg. Sand – 0.20 cu m. On brick flooring in cement mortar per 100sq. m area Wet mortar

1:2 cement – 136 Kg. Sand 0.186 cu m. 1:3 cement – 102 Kg. Sand 0.205 cu m. 1:4 cement – 76 Kg. Sand 0.205 cu m. 1:6 cement – 50 Kg. Sand 0.205 cu m.

Plastering Cement plaster on walls per 100 Sq. m. Proportion of 12mm thick plaster 1.44 cu m of wet plaster Cement : sand 1:2 1:3 1:4 1:5 1:6 Extra Mortar

Cement Kg.

Sand M3

979 734 547 446 360 20%

1.731 1.541 1.532 1.516 1.512

15mm thick 1.72 cum plaster Cement Kg. 1170 877 654 533 430 15%

20mm thick wet 2.24 cu m plaster Sand M3 Cement Kg. 1.638 1523 1.842 1142 1.831 851 1.812 694 1.806 560 12% of

of wet Sand M3 2.132 2.398 2.383 2.360 2.252

Note : 1. Extra percentage is required for filling up joints in brick work and uneven surfaces. 2. When plaster is to be finished with a floating coat of neat cement lake 220kg /100 sq. m. extra cement. 3. For plastering on ceiling 6mm thick the quantities will be half of 12mm plaster.

35

WHITE WASHING & PAINTING Qty. of un slaked white lime per 100 sq. m. of new surface One coat Two coats Three coats

-

12 kg. 22 kg. 32 kg.

Note : Old surface will require 10kg of lime for 1st coat Labour for 100 Sq. m. One coat white wash Two coats white wash Three coats white wash

1/2 white washer + ½ helper 1 white washer + 1 helper 3/2 white washer + 1.5 helper

For ceiling white washing add 25% extra labour Snocem or cement paint for 100 sq. m. 1st coat 2nd coat

-

30kg. 20kg.

1 painter + 1 helper 2 painter + 2 helper

Roofing Roofing with G.I. sheets per 10 sq. m 15cm end laps and 2 corrugation side laps (GI sheets –22 gauge 0.8mm thick) Sheets reqd. 12.8 S. m. Seam bolts & nuts 2.5x6 mm size 30 Nos. J or L hooks bolts & nuts 8 mm dia = 25 Nos. Bitumen and GI washer = 55 Nos. Labour sheeter – 1 No. helper 1 No. Sheeting with corrugated asbestos cement sheet per 10 sq. m area AC sheets 7mm thick = 11.5 sq. m. J Or L hooks or crank bolts and nuts 8mm dia – 25 Nos. Bitumen & flat washers -25 Nos. Labour:- Sheeter – 1 No. helper 1 No. Add for ridge according to length and sheeter and helper 5% to above labour. No. extra bolts or screws are required for fixing of ridge. Holes in asbestos cement sheet should never be punched but should always be made by drilling.

36

CONCRETING IN COLD WEATHER The rate of hardening and setting of concrete is very much retarded when the temperature falls below 21 deg. C (70 deg. F). At about 10 deg. C. (50 deg. F.) the action of setting slows down to about one-half of what it is at 21 deg. C. In addition to the slowing down or stopping of hydration and hardening, there is also danger of disintegration of unset concrete due to the disruptive effect set up by the expansion of the mixing water as it freezes. During cold weather concreting shall be abandoned when the temperature falls below 4.5 dg. C (40 deg. F.). (Use immersion thermometer inserted in concrete near forms or surface for recording temperature.) it can be carried out with complete success provided certain remedial measures and precautions are taken. The most convenient method is to heat the mixing water and, for very low temperatures to heat the aggregate as well. Heat the mixing water to 66 deg. C. (150 deg. F.). On no account shall the hot water be added to cement alone. Aggregates may be heated to 21 deg. C, mixer drum may also be warmed. Cement must not be heated. Temperatures of fresh concrete exceeding 21 deg. C. (70 deg. F.) are undesirable due to the higher water requirement, and likelihood of cracking when the concrete contracts on cooling, and relatively low strength. For most constructions, the right temperature of concrete at placement is somewhat below 21 deg. C. Concrete with a low water / cement ratio is less liable to damage by frost, and for good resistance to frost it is considered that the average water / cement ratio should not exceed 0.60 (30 liters per 50 kg of cement). Fresh concrete must not be allowed to freeze. If concrete is frozen, setting and hardening ceases. Avoid the use of frozen aggregate. The concrete placed shall be protected against frost by suitable covering. Concrete damaged by frost shall be removed and work redone. Provide layers of straw or other insulating material on the freshly laid concrete surface as soon as the concrete is hard enough to sustain it without detriment. An insulating layer for covering concrete may be composed of waterproof paper overlaid with a layer of straw and finally with second layer of water proof paper. In frosty or other adverse weather conditions, use of colloidal concrete may be considered. An increase of cement content of the mix by about 20 to 25 per cent, use of rapid hardening cement with an admixture of calcium chloride or, high alumina cement are usually recommended. With high alumina cement concreting can proceed without any further precautions provided that the temperature is not at freezing point or below and the materials are not frozen. “Accelerators” are used in cold weather to increase the rate of hardening and thereby reduce the likelihood of failure. They accelerate the hydration of the cement and increase the rate of evolution of heat; thus the temperature of the concrete is raised and the freezing point of the mixing water is lowered, enabling concreting to be carried out when the air temperature is near or slightly below freezing point.

37

As far as practicable, the use of accelerators or admixtures should be avoided. Calcium chloride is the most commonly used material for accelerating hardening of the concrete and is perhaps the most reliable, which may be used up to 2 per cent max : (prefer 1.5 per cent) of the weight of cement. Quantity in excess of this proportion is harm full. In no circumstances should this chemical be added to high alumina cement. Calcium chloride is a white deliquescent and hydroscopic salt commercially available at low cost in flakes or granular form and delivered in moisture proof bags or airtight drums, and should be stored in a dry place. It is dissolved in the mixing water to which cement is added after wards. Calcium chloride should not be placed in contact with water or mixed dry with aggregate. Calcium chloride shall not be used where reinforcement is provided in the concrete. The use of calcium chloride approximately halves the setting time, the concrete must be placed in position and finished with the minimum of delay because of the repaid setting. Common salt (sodium chloride) lowers the freezing point of water. For temperatures below 0 deg. C. dissolve 1 kg. of salt in 170 liters of water and which may be slightly more for lower temperatures. Larger percentages of salt appear to weaken the concrete. Salt over 5 per cent by weight of cement is injurious as it not only affects the strength of the concrete but may also cause rusting of the reinforcement and efflorescence. Much dependence should not be placed on salt for prevention of freezing. Salt should be thoroughly dissolved or the results will not be satisfactory. Timber form work is a valuable insulating agent and should be used in cold weather. The concrete must be kept warm and protected from frost after it has been placed and until it has hardened. Heat losses from concrete are greater in the first few hours, therefore, protective methods must be applied as soon as possible after placing. Suitable methods of protection are wrapping or covering the concrete with dry Hessian or backing, straw blankets, old paper cement bags, tarpaulins or a 15 cm layer of dry straw. If timber formwork is used it should be left in position as long as possible. Since the rate of hardening of concrete will be slower in cold weather, formwork will have to be left in position somewhat longer. Before any formwork is stripped it must be made certain that concrete has hardened sufficiently. Precaution must be taken against coverings being displaced by wind. Reinforcement that is left protruding from the concrete constitutes a danger spot since it offers an easy path for heat losses. It should therefore be wrapped. Steam is sometimes used for heating the concrete, which is introduced between the coverings and the concrete.

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KNOW YOUR CEMENT AND CONCRETE As a site engineer one must know the type of cement which is being used or recommended for the project. For any type of cement O.P.C.i.e. ordinary Portland cement is the basic cement. In practice either OPC or slag cement or pozzolona cement may be used. The ultimate compressive strength is more or less same. Further to these cements various additions and admixtures are added, to form quick setting cement, rapid hardening cement, and high strength cement, shrink free cement. Water proof cement, low heat emission cement, colored cements etc. These additives and admixtures must be used as per recommendations of the Manufacturers. O.P.C. which is the base contains essentially following materials. 1) lime 60 to 70 % 2) silica 17 to 25 % 3) alumina 3 to 8 % These in gradients are thoroughly mixed with water to form a slurry which is heated and dried to form clinkers, small proportion of gypsum is added to control rate of setting and then ground to very fine powder packed and is ready to use. The various exact proportions of ingredients vary for different manufacturer depending upon the quality of materials available. Again now a days OPC. Of 33, 43, and 53 grades are available. Out of these 43 grade is most commonly used. The grade of cement depend upon the fine ness of particles, higher the grade finer is the particle size. When higher grade of cement is used more care should be taken for curing, if curing is not proper, shrinkage cracks are common in concrete and plasters made by using higher grade of cement.

Following requirements are essential for various toypes of cements. 1. SETTING TIME TYPE OF CEMENT INITIAL SETTING TIME FINAL SETTING TIME Normal setting Not less than 30 minutes. Not more than 10 hrs. Rapid hardening Same Same Quick setting Not less than 5 minutes. Not more than 30 minutes. Low heat Not less than 1 hour. Not more than 10 hrs. High alumina Not less than 2 hrs not more Not more than 2 hrs after than 6 hrs. initial set. The compressive strength of concrete varies with different type of cement as shown below concrete under reference is in ratio 1:2:4 and water cement ratio 0. 60 .28 days strength with ordinary port land cement if taken as .1 Mix with ordinary cement ---1.00 “ “ Aluminous cement ---2.00 “ “ rapid hardening cement--1.200 “ “ low heat cement---------0.82

Loss of strength of cement with time. As a result of long storage of cement the compressive strength gets reduced following table is for general guidance. Fresh cement has strength Cement stored for 3 months

100%

39

has strength Cement stored for 6 month has strength Cement stored for 12 months has strength Cement stored for 24 months has strength

75 to 80 % 60 to 65 % 55 to 60 % 45 to 50 %

The time is estimated from the date It leaves the factory this indicates that cement should be used when it is fresh say within a month or two from the time it arrives at site. If cement is to be used which is 3 month or more old, it should be retested in the laboratory and should be used only when results of test are satisfactory, for any load bearing structures like columns, footings, rafts, beams, slabs or in machine foundations. When old cement is to be consumed it should be used in lean mixes like providing mud met or P.C.C. below R.C.C. or where filling is to be done, or below ground stabs etc. EFFECT OF MOISTURE. Cement has great affinity for water and as soon as it comes in contact with water process of hydration starts, and hard lumps are formed and strength is lost. Even moisture absorbed from atmosphere by cement kept in bags gets hydrated and looses strength; hence cement should always be stored above 1 to 2 feet from ground and kept properly covered. Absorption up to 1 % can be tolerated and if observed, such cement should be used immediately. If absorption exceeds 4 to 5%, cement is useless for all ordinary purposes. Cement bags should be opened only when it is to be emptied in the mixer drum. PORTLAND SLAG CEMENT. Portland slag cement: is intimately ground mixture of port-land cement clinker and granulated slag with addition of gypsum and permitted additives or and intimate uniform blend of port-land cement and finely ground granulated slag. A short description of the in gradients is as given below. PORTLAND CEMENT CLINKER. It consists mostly of calcium silicates obtained by heating to incipient fusion a predetermined and homogenous materials mainly containing ca 0 (lime) and Si02 (silica) with smaller portion of Al203 (alumina) and Fe203 (iron oxide) GRANULATED SLAG. Slag in granulated form is used for manufacturing hydraulic cement. It is basically non metallic product which has necessarily glass containing silicates and aluminum-silicates of lime and other bases. Blast furnace slag contains all above ingredients. Slag which is produced simultaneously along with iron in Blast furnace or in electric pig iron furnace. The slag produced is in molten form, this molten slag is granulated by rapid chilling or by quenching the molten slag with water or steam and air. MANUFACTURING OF PORTLAND SLAG CEMENT. It can be produced by 2 methods. In first method granulated slag in required quantity is added to the Portland cement ingredients like clinker etc. as explained in above and grinded together to the required fineness. In second method final grinded powder of granulated slag is mixed in required proportion to ready Portland cement and mixed thoroughly to give a homogeneous mass to be used as Portland slag cement in various construction activities. PERCENTAGE OF CRANULATED SLAG IN CEMENT.

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The granulated slag powdered content in Portland cement varies from 25% to 70% of the port land slag cement. SETTING TIME. Setting time of Portland slag cement when tested by Vicat Apparatus as per IS 4031 part V should be as below. Initial setting time. Not less the 30 minutes. Final setting time. Not more then 600 minutes. COMPRESSIVE STRENGTH. The average compressive strength of minimum 3 nos. of mortar cubes area of face 50 cm 2, and mortar composed of 1: 3 ratio (one part of Portland slag cement and 3 parts of standard sand by mass and (p/4+3.0) percent (of combined mass of cement + sand), water and prepared, stored and tested in the manner described in IS 4031 (part 6) ; 1988 shall be as below. 1) 72+1hour Not less than 16 MPa. (3 days) 2) 168 ±2hour Not less than 22 MPa (7 days) 3)672±4hour Not less than 33 MPa (28 days) Where 1 MPa. = 1N/mm2 = 0.102 kg/mm2 Standard sand shall confirm to I.S. 650: 1966. “p” is the percentage of water required to produce a paste of standard consistency.

ADVATAGES OF PORTLAND SLAG CEMENT. 1) Physical properties are similar to port land cement. 2) It has low heat of hydration. 3) It is better resistant to soils and water which contain excessive amounts of Sulphates of alkali metals, Alumina, and iron and also resistant to acidic waters. Due to these qualities it is suitable for use in marine works. 4) It uses Blast furnace slag which is otherwise a waste product. The disposal of slag from blast furnace and electric are furnace was a big problem be-fore port land slag cement production came in to practice. 5) It also increases production of cement by the percentage of slag is mixed in port- land cement and thus gives economical benefit. For more details IS 455; may be referred. POZZOLANA CEMENT. Pozzolana cement is ordinary Portland cement in which fly ash obtained from thermal power stations where coal is used as fuel for boilers. Huge quantity of fly ash is produced and is practically a waste product. The disposal of fly ash is a big problem to power houses. Using fly ash as admixture in cement has led to saving of scares construction minerals. For using fly ash as admixture to Portland cement, it is necessary to have proper collection system of quality fly ash from its source of production (thermal power houses). Use of fly ash in cement concrete or cement mortar has three different and specific purposes. One, use of fly ash as admixture, Second, use of fly ash as fine aggregate and Third, use of fly ash as Pozzolana.

41

Considering all three above aspects Indian standard bureau has made IS 3812-1981 based on the current knowledge and experience gained from the use of fly ash. It has been established that fly ash up to 12%may be used for replacement of cement without affecting the quality and strength safely. Fly ash to be used in cement can either be added along with clinker and gypsum at the time of grinding to produce Pozzolana cement or it can be added separately to Portland cement and mixed thoroughly to produce a homogeneous mass and used in construction. GRADES OF FLY ASH. Fly ash which is used in mixing is divided in 2 grades as per is 3812 - 1981 GRADE 1:- for incorporation in cement mortar and concrete and in Lime Pozzolona mixture and for Manufacture of Portland Pozzolana cement. GRADE2:-for incorporation in cement mortar and concrete and in Lime Pozzolona mixture for more details regarding fly ash, type and quality IS 3812 part 1 and 2 may be referred. An article published in journal of structural engineering volume 33 number 3 gave following results which are worth noting. Mechanical properties of hardened concrete modulus 28 days strength N /mm2 Type of concrete. Conventio nal concrete. Fly ash concrete.

%dosage of waste

Mix proportion

0 10 20

Modulus of elasticity X10-4 N/mm2

Compressive strength.

Split tensile strength.

Flexural strength.

1:2:4

24

3.24

4.81

3.91

(0.9+0.1):2:4 0.8+0.2.):2:4

27 25

3.68 3.20

4.94 4.50

5.12 4.18

Observation: - There is 5 to 12.5% increase in compressive strength at 10% replacement of cement by fly ash compared to strength of Conventional concrete. There is marginal decrease in direct tension and flexural strength at 20% replacement of cement by fly ash. There is scope for research to test concrete in which cement up to 20% is replaced partly by granulated slag and partly by fly ash and study results as to how with various combinations of both of these items the concrete will behave CEMENT CONCRETE. cement concrete is either made at construction site by using mixers, which are available in different capacities and types, for this coarse aggregate in the form of crushed stones and fine aggregate in the form of river sand are stocked at site and mixed in required designed proportion as per mix design to cement, water and admixtures are added. As per design proportions and mixed in the mixer machines and desired concrete is produced and used. The precautions required are that aggregate and sand should be of good quality and free from dust. If dust is observed both aggregate and sand should be thoroughly washed before use. Dust or clay should be less the 1.5 to 2% only. The dust are clay present forms a very thin film on the particles of sand and aggregate and reduces grip or adhesion of cement. Presence of clay also retards the setting action of concrete and increases drying shrinkage and has an adverse effect on final crushing strength of concrete. Hence all precautions must be taken to remove clay or silt from aggregates be fore use. 42

SUPPLY OF CONCRETE FROM BATCHING PLANTS. When concrete is required in huge quantities it is supplied from batching plants in transit mixers. The batching plants are located 15 or 20 kilometers (even more) from the site of construction, order is placed on batching plants for required grade of concrete (M15,M20,M25,M30 etc.) along with quantity required. At batching plant required mix design is done along with additives required and ready made concrete is supplied. To the consumer. At worksite slump test is carried out as soon as concrete in Transit mixer is received. The concrete is poured through concrete pumps with the help of delivery pipe in foundations and vibrated. Readiness of shuttering and reinforcement binding before ordering is a pre condition. In all big projects concrete is supplied through batching plants only. Use of mixer machine is common only in residential building and small projects like, bridges culverts or projects where batching plants. Do not exist with in a reasonable distance. Test cubes are taken from the concrete during filling the foundation and are tested for 7 and 28 days strength, to asses and ensure quality of concrete. Even when concrete is supplied through Batching plants the quality of concrete depends upon type of cement and coarse and fine aggregates used. In any of the method of supply quality control by taking cubes during concreting is a must. These cubes are to be kept on or near concreted surface and cured as per curing of main foundation to arrive at proper conclusion from the results of 7 or 28 days crushing strength. It is a general practice that cubes are kept fully immersed in water for 7 or 28 days and taken out of water just before testing. This is a wrong practice and must not be allowed. From such results you can never get correct idea of mass concrete which is cured only 2 or 3 times a day, hence testing cubes should be given same treatment of curing as the mass concrete. It will be clear from above that for good and dependable quality of concrete strict supervision at every stage i. e. during binding reinforcement, shuttering, mixing, pouring and vibrating is required. Any laps at any stage will result in week concrete structure and will fail in serving the purpose for which it has been provided in due course of time. Another point which is worth paying attention is that once the concrete sets, (what ever quality it may be) and if the cube test shows less strength and defects are observed after removal of shuttering any type of remedial measure is very costly. Remedial measures like pressure grouting with cement or with chemical can only make up the loss to some extent only but no agency takes guarantee that after rectification the concrete will be as good as dependable concrete during the life time of the structures. Some time concrete structures like columns, pedestals and foundations are to be broken and rebuild. This is done by using pneumatic or electrically operated chisels These tools induce hair cracks in the concrete below the broken surface which are not visible. Cracks provide passage for underground water and damage the reinforcement by rusting and loosing the grip of reinforcement with concrete in due course of time. Following general defects are observed in concrete, since it is practically impossible to control each and every activity, it becomes more difficult when so many agencies, and suppliers are involved at site. DEFECTS OF CONCRETE. Cracks Cracks in concrete can be categorized as minor hair cracks and major cracks. minor hair cracks. These appear on the surface film of cement layer on concrete and do not extend in side .Such cracks do not affect strength of concrete and can be removed by hard wire brushing the top cement film, easily. The main cause of appearance of hair crack is mainly due to unequal shrinkage of the surface concrete and concrete mass behind it. It is also due to bulging of shuttering. On tension side hair cracks appears due to week tensile strength of concrete compared 43

to steel. These cracks appear after the steel reinforcement takes load, improper curing also contributes to above reasons. After removal of top skin by hard wire brushing soon after the concrete is set and a thin coat of cement based water proof chemical is given. MAJOR CRACKS. These types of cracks can be seen by naked eye on the top surface near projecting heavy vertical reinforcement and foundation bolts in column and pedestals. These are wider and extend quite deep say 50 to 200 mm and more. These also extend up to corner of surfaces. Their appearance is haphazard and crisscross. Here also the reasons are 1) improper curing 2) use of high grade of cement 3) in sufficient cover 4) providing excessive reinforcement steel. 5) Difference in rate of cooling between upper layer of concrete and concrete mass in side which causes unequal shrinkage of surfaces. Shrinkage in dry and hot areas is much greater in summer and in Gulf countries, where temperature during day rises up to 50`c, and above. Due to this special arrangement for keeping the concrete surface continuously wet and cool is required. It may be mentioned that curing after concreting is taken casually and is seldom paid serious attention, which is wrong, many of cracks can be avoided if serious attention is paid for making special arrangements for proper curing prior to concreting. REMEDIES. 1) For major cracks the best thing is to break the concrete about 100 mm below the limit to which crack is extending and recast by using concrete mixed with special non shirking cement based compound. These are available in market and are produced under different brand names. 2) Cracks can also be filled with non shirking chemicals by pressure grouting. These chemicals are very thin (even thinner than water) and fill up all cracks and cavities and solidify with in 24 to 48 hours. 3) Grouting can also be done with, epoxy based non shrinking and free flowing grouting materials with pressure. These are also available in market under different brand name. One caution in using chemical grouting material is, to discuss with representative of the supplier/ producer of the material and decide a particular type of material as recommended by him. Do not decide a particular brand of material only after reading the literature which is often confusing. It is a big relief that in India and other countries now a days manufacturers themselves under take such grouting with guarantee. It is better to engage such agencies rather purchasing the grouting chemical from supplier and carrying out the work locally or through labor contractor. Please note in later case the guarantee/warranty does not stand valid. Honeycombs in concrete: - Honeycombs are hollow spaces and cavities left in concrete mass on surface or in side the concrete mass where concrete could not reach. These look like honey bees nest. Honey combs which are on sides are visible to naked eyes and can be detected easily as soon shuttering is removed. Honey combs which are inside mass of concrete can only be detected by advanced techniques like ultrasonic testing etc. Honey comb is due to non reaching of concrete to all places due to which cavities and hallow pockets are created, main reasons are 1) improper vibration during concrete. 2) Less cover to reinforcement bars 3) use of very stiff concrete (this can be avoided by controlling water as per slump test). 4) Places like junction of beam to beam to column and to one or more beams are the typical spots where honey combs are observed. This is due to jumbling of reinforcement of beams and column rods at one place; special attention is required at such place during concreting and vibrating. 5) Presence of more percentage of bigger size of aggregate in concrete also prevents concrete to fill narrow spaces between the reinforcement rods.

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REMEDIES FOR HONECOMBS. Strictly speaking wherever honeycombs are observer concrete should be broken and the portion should be re concreted after applying grouting chemical to the old surface. Honeycombs as a defect not only reduces the load bearing capacity but water finds a easy way to reinforcement rods and rusting and corrosion starts. Corrosion is a process which continues through reinforcement‟s rods even in good concrete, this result in loosing grip between rods and concrete, which is very dangerous to safety and life of concrete structures. R.C.C. structures have failed with in 20 or 30 years of there construction which is less than half their projected life. Especially no risk should be taken in case of columns, Machine foundations, Rafts, Beams etc, where breaking and recasting is the only best way. In case of honey combs on surface pressure grouting with cement based chemicals which are non shrinkable can be adopted after taking opinion of the designer and acting as per his advice. It will not be out of context to point out that contractors and their supervisors are in the habit of hiding honey combs by applying super facially cement plaster on the honey combs, hence site engineer must be very cautious. At places of junction of columns and beams concrete with strictly 20mm and down aggregates should be used with slightly more water and cement to avoid honeycombs. Taping with wooden hammer the sides of shuttering from outs side during concreting and vibrating will help minimizing honeycombs to a great extent in case of columns and beams. Use of thinner needle say 25mm or less with vibrator at intricate places of concreting will also help in reducing honey combs. Segregation Segregation is separation of ingredients of concrete from each other. In good concrete all concrete aggregates are evenly coated with sand and cement paste and forms a homogeneous mass. During handling, transporting and depositing due to jerks and vibrations the paste of cement and sands gets separated from coarse aggregate. If concrete segregates during transit it should be remixed properly before depositing. How ever a concrete where initial setting time is over, should not be used. MAIN CAUSES OF SEGREGATION. 1) Use of excess quantity of water. This is a general tendency when concrete is made at site in mixer machine by workers. 2) Excessive vibration of concrete when mechanical needle vibrators are used, as a result of excessive vibration heavier particles sink to bottom and liquid comes on top. 3) Depositing concrete from top in underground foundations and rafters, concrete should never be thrown from a height when brought in buckets by laborers, which is a general tendency observed at site. REMEDY. Where ever depth is more than 1.5 meters it should be deposited through temporary inclined chutes. The angle of inclination may be kept between 1:3 and 1:2 so that concrete from top of chutes travels smoothly to bottom, use of small quantity of free water from top at intervals helps in lubricating the path of flow of concrete to bottom smoothly. The delivery end of chute should be as close as possible to the point of deposit. Segregation in deep foundations and rafts of thick ness more than 1 meter, there is every possibility of presence of segregated concrete near bottom or in center if proper supervision is not there. Such segregation can be detected by advanced method of testing like ultrasonic testing. In case of doubt random ultrasonic testing should be conducted and if it is present designer‟s opinion should be taken. This type of segregation can be rectified by pressure grounding with special chemical compounds. After any defect rectified by pressure grouting core test has to be performed to ensure that the strength of concrete has reached to the desired level.

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PROPER METHOD OF POURING & VIBRATION OF CONCRETE. Common rule for pouring is that in no case concrete should be poured at edges near shuttering and vibrator needle should be inserted away from shuttering the needle should not touch shuttering and reinforcement rods. Insertion of needle in concrete should be practically vertical and point of insertion should be about 500mm (approximately) away from each other. Sides of shuttering should be tamped by wooden hammer from outside when concreting reaches near ends. Needle should be removed after 1 to 1:5 minutes as soon as cement slurry appears. Over vibration will cause segregation which is not desirable.

CONCRETING OF COLUMNS PEDESTALS AND FOOTINGS. Concreting should start from the center of vertical bars to the end and vibrated so that concrete spreads evenly on all sides. Proper keys should be provided in the center of column reinforcement and walls. All upper surfaces of column and walls should be made rough by wire brush after initial setting of concrete. This is required to provide a proper grip between concrete of stem part with footing and walls and foundations. Always pour 1:1 cement and sand slurry on the footing and foundations before column stem and wall concreting is started, to avoid separation of stem/ wall where a cold joint may be formed. Immediately in a day or two starters for column and wall should be casted with proper alignment and again the upper surface of starter should be made rough. This can be easily achieved simply by spreading and light pressing coarse aggregates particles when concrete is still green in such a way that part of coarse aggregate is out side and part goes inside. This method of making top surface rough is to be adopted along with providing key at all places in columns, pedestals, vertical walls which are always concreted after concreting of footing and rafts concreting is over (approximately two or three days letter). These measures provide a proper grip between the surfaces. In addition to above dowels in between outer main bars of wall and column are inserted when concrete is wet to provide further grip between old and new concrete surfaces. These dowels are 600 to 800 mm cut pieces of reinforcement bars, which are inserted in green/wet concrete such a way that half length is projecting and half length is inside concrete. CONCRETING OF RAFTS. Rafts are always bigger in dimensions (length, width and height) and vertical reinforcement are to be provided at proper places along with reinforcement for pedestals, walls, machine foundation, pockets, bolts, inserts, conduit pipe, sumps etc. before concreting is to start. Hence it is required to check all these items thoroughly for proper location and fixity, so that these items are not disturbed from their location during concreting, only after checking these items along with reinforcement rods pouring of concrete should be allowed. It is very difficult to provide missing items or correct their location once concrete is set. Concrete in rafts is always done from one end to other end along width and not along length, with proper vibration as has been explained earlier. If for pockets solid thermo coal blocks are used these should be left in concrete even after curing time is over. These are removed only when machines are to be erected. If removed earlier these pockets which will leave a wide deep hollow space in the raft and may cause an accident when persons walk over it.

Short notes on sampling, testing, and acceptance of concrete cubes. (Ref :- National building code of India 2005 section section 5). The characteristic strength is defined as the strength of material bellow which not more than 5 % of the test results are expected to fall. Conditions of concrete and grade with concrete with water cement ratio and minimum cement required are as specified in the following table (ref clause 5.1.2, 5.1.3, 7.2.4.1 and 8.1:2)

46

Minimum grade of concrete M20 M25 M30 M35 M40

S.NO 1 2 3 4 5

MILD MODERATE Severe Very severe Extreme

Maximum free water content ration 0.55 0.50 0.45 0.45 0.40

Cement Content (minimum) kg/m3 300 300 320 340 360

Frequency of sampling clause 14.2 Quantity of concrete in the work m3 1-5 6-15

Number of samples 1 2

16-30

3

31-50

4 4+1 additional sample for each additional 50m3 or part thereof

51 and above

1 2

Compressive grade M 20 M 25

Strength required after 28 days strength of 150 mm cube after 28 day N/mm2 20 25

3

M 30

30

1

M 35

35

S.NO

14.4 Test results of sample. The test results of the sample shall be the average of the strength of three specimens. The individual variation should not be more the ±15% of the average. If more the test results of samples are invalid. Acceptance criteria: - clause 15.0 Compressive strength:- clause 15.1.0 The concrete shall be deemed to comply with the strength requirement when both the following conditions are met. a) Mean strength determined from any group of four non overlapping consecutive results complies with the appropriate limits below

Specified grade of concrete 1

Mean of the group of 4 non-overlapping consecutive Test Results in N/mm2 2

Individual test result in N/mm2 3

M 20 or above

≥fck + 0.825 x established standard deviation(rounded off to nearest 0.5 N/mm2) or 2 ≥fck -4 N/mm , whichever is greater

≥fck -4 N/mm2 Wh

ere fck is characteristic cube compress ire strength of concrete. 47

b) The strength determined from any test result is not less than the specified characteristic strength less 0.3 N/mm2. Quantity of concrete represented by strength test results clauses (15.3). The quantity of concrete represented by a group of four consecutive test results shall include the batches from which the first and last samples were taken together all intervening batches. For the individual test result requirement given in col. No 3 only the particular batch from which the sample was taken shall be at risk. Where the mean rate of sampling is not specified the maximum quantity of concrete that four consecutive test results represent shall be limited to 60 m3 CORE TEST (CLAUSE 16.4) The points from which cores are to be taken and the numbers of cores required shall be taken shall be at the discretion of the engineer -in-charge and shall be representative of the whole of concrete concerned. In no case however, shall fewer than three cores be tested. 16.4.3 Concrete in the member represented by a core test shall be considered acceptable if the average equivalent cub test strength of the cores is equal to at least 85% of the cube strength of the grade of concrete specified for the corresponding age and no individual core has a strength less than 75% In case the core test results do not satisfy the requirements or where such tests have not been done, load test may be resorted to.

48

POUR CARD PROFORMA Sr. No. -------Project Name ---------------Drg. No. ----------------------1. 2. 3. 4.

5.

Owner -----------

Date of Concreting --------------------------Time of Starting -------------------------------Volume of Concreting ------------------------- M3 Ratio of concrete Mix 1:2 :4 1 : 1.5 : 3 1:3 :6 1:4 :8 No. of cement bags required as per theoretical calculation --------------- No.

6.

P.C.C. top level a. As per drg. ---------b. Actual at site level -----------

7.

Concrete top level a. As per drg. ---------b. Actual at site level -----------

8.

Steel inserts level a. As per drg. ---------b. Actual at site level ----------9. No. of bags actually consumed. 10. Time of completion. Notes : a. b. c. d. e. f. g. h.

Certified that reinforcement has bee provided as per approved bar bending schedule Shuttering has been checked and approved. Pockets for machine foundations and inserts are provided as per drawing. Concrete vibrators, concrete mixers & water pumps are in working condition. Adequate water is arranged Adequate skilled & unskilled labour and supervisory staff is arranged by contractor. Adequate cement, sand, aggregate water proofing compound plastisizer (if required) is available at work site Plastisizer / water proofing chemical as recommended with ratio of mixing

CONTRACTOR OF COMPANY

ENGINEER/

Yes / No. Yes / No. Yes / No. Yes / No. Yes / No. Yes / No. Yes / No. -----------

SUPERVISOR

CONSULTAN’S ENGINEER The above pour card should be made in 3 copies. One copy to be kept by each signatory for record. Proforma 49

BAR BENDING SCHEDULE PROFORMA Date -------------DRG. No. --------------------

Shape

7

8

9

10 11

CONTRACTOR COMPANY

12

13

Total WT

Total Length

6

5

Unit WT

Length of each

4

Length Total (6+9+13)

No. of Laps

3

Length of All

Total Length

2

Length of One

Length of One Nos.

1

Nos.

Shape

Joints Chairs Provided

Dia

As Per Provided

Sr. No.

As Per Drawing

Sr. No. -----Project / Building ------------------

ENGINEER/ SUPERVISOR OF CONSULTAN’S ENGINEER

The above bar bending schedule should be made in 3 copies. One copy to be kept by each signatory for record.

50

WEIGHTS OF BLDG MATERIAL S. No. 1. 2.

Aluminum Cast Aluminum Wrought

2580-2700/m 3 2640-2800/m

3.

Al. Sheets Per mm

2.8 Kg/m

Material

9. 10. 11.

Asbestos Cement Sheets 6mm Flot Thk. 6mm Thk. Asbestos Corrugated Asphalt solid Brick Ballast Stone Ballast Consolidated Brass Bricks Common Burnt Bricks Burnt Pressed

12.

Fire Clay Bricks

4. 5. 6. 7. 8.

13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

A)

Brick Work with Common Bricks With Machine cut bricks 100mm thick brick work Cast Iron Cast Steel Cement Tightly Packed Coal Loose Coke Plain Concrete with Stone aggregate Reinforced Cement with 2% steel Concrete with 5% Steel Brick Aggregate Stone Aggregate Copper Sheets Per mm thick

Weight kg. 3

S. No. 27. 28.

Material

Weight Kg.

Cost Copper Wrought Copper Glass Rolled Plate 6mm thk.

8790-8940/M 3 8840-8940/M

2

2

29.

11 Kg/m

2

30.

Glass Sheet 1mm thick.

2.5/M

16 Kg/m

2

31.

ICE

900/M

3

32. 33.

Pig Iron Grey Cast iron

7200/M 3 7030-7130/M

3

34.

White Cast Iron

7580-7720/M

8550/M 3 1600-200/M 3 1760-1840/M

35. 36. 37.

11350/M 3 11/M 3 820/M

3

38.

Lead Solid Cost Lead Sheets Per mm thk. Kerosene Premixed bitumen macadam

3

39.

Mild steel

7850/M

3

40. 41. 42. 43. 44. 45. 46.

Cement mortar Petrol Sand dry & clean River sand Wet Sand Wet Silt Mild steel

2080/M 3 675-690/M 3 1450-1600/M 3 1840/M 3 1760-2000/M 3 1760-1920/M 3 7850/M

3

47.

Rolled steel

7840/M

2200-2300/M 3 930-1260/M 1920-2080/M 3

1760-2000/M 1800-1950/M 2400/M 2 192//M 3 7200/M 3 7840/M 3 1700/M 3 800-900/M 3 1000/M 2300/M

2

8.69/M

3 3

3

3

3

2200/M

3 3

3

49. 50. 51.

2100-2200/M 3 2080/M 3 2100-2200/M

52.

Wrought iron

7700/M

53.

Zinc sheets perm thick

7.1/M

48.

3

2580-2700/M 3 1850/M 3 2250/M

2

Stone masonry mortar & rubble Mortar and random rubble Dry rubble Dry random rubble

3

2400-2500/M

2

17 Kg/M

3

2500/M

3

3

3

Average cost of labour for civil works. The average cost of labour for civil work for estimation purpose is taken 30 to 40% of material cost.

51

SQUARE AND ROUND BARS 0.7843 KG/CM2 PER METER OR 1 CFT OF STEEL = 490 LBS

Diameter or width mm 5.0 5.5 6.0 7.0 8.0 9.0 10 11 12 14 16 18 20 22 25 28 32 36 40 45 50 56 63 71 80

Weight per meter  Kg  Kg 0.20 0.15 0.24 0.19 0.28 0.22 0.38 0.30 0.50 0.39 0.64 0.50 0.78 0.62 0.95 0.75 1.13 0.89 1.54 1.21 2.01 1.58 2.54 2.00 3.14 2.47 3.80 2.98 4.91 3.85 6.15 4.83 8.04 6.31 10.17 7.99 12.56 9.86 15.90 12.49 19.62 15.41 24.62 19.34 31.16 24.47 39.57 31.08 50.24 39.46

Sectional Area  Cm2  Cm2 0.25 0.20 0.30 0.24 0.36 0.28 0.49 0.38 0.64 0.50 0.81 0.64 1.00 0.79 1.21 0.95 1.44 1.13 1.96 1.54 2.56 2.01 3.24 2.54 4.00 3.14 4.84 3.80 6.25 4.91 7.84 6.16 10.24 8.04 12.96 10.18 16.00 12.57 20.25 15.90 25.00 19.64 31.36 24.63 39.69 31.17 50.41 39.59 64.00 50.27

Perimeter  Cm  Cm 2.0 1.57 2.2 1.73 2.4 1.88 2.8 2.20 3.2 3.51 3.6 2.83 4.0 3.14 4.4 3.46 4.8 3.77 5.6 4.40 6.4 5.03 7.2 5.65 8.0 6.28 8.8 6.91 10.0 7.85 11.2 8.80 12.8 10.05 14.4 11.31 16.0 12.57 18.0 14.14 20.0 15.71 22.4 17.59 25.2 19.79 28.4 22.31 32.0 25.13

USEFUL FORMULA The circle Area of circle

Circumference

=

d2 ------4 d

Cylinder Cylinder Area Vol.

= =

d x h Where d = dia of Base, h= Height of Cylinder. r2 h

Ellipse

=

Area =

Where „d‟ is dia of circle = 2r r= Radius of Circle.

1/4Dd = 0.7854 D x d, Where D major axis (long axis) d minor axis (short axis)

ze Perimeter or circumference = 1.82D +1.315d Perabola Area = base x 2/3 height. 52

Polygons Sum of interior angles of polygon regular or irregular is always = 180 0 x (number of sides –2) Table of regular polygons Name of Polygon Triangle Tetragon Pentagon Hexagon Octagon Decagon Dodecagon Angle S R R

= = = =

No. Sides 3 4 5 6 8 10 12

of Angle A 00 60 90 108 120 135 144 150

Area S2 x 0.433 1.000 1.721 2.598 4.828 7.694 11.196

R Sx 0.577 0.707 0.851 1.000 1.307 1.618 1.932

Side Rx 1.732 1.414 1.176 1.000 0.765 0.618 0.517

rx 3.464 1.000 1.454 1.155 0.828 0.650 0.543

r Sx 0.289 0.500 0.688 0.866 1.207 1.538 1.866

Angle contained between 2 sides Side of polygon Radius of circum scribed circle Radius of inscribed circle

Trapezium Area = Sum of parallel sides x ½ height. Simpson’s rule for area of irregular figures Procedure Divide the area or figure into an even number (n) of parallel strips by means of (n+1) ordinates, spaced at equal distance „d‟ Then Area of the figure = 1/3d [first ordinate + last ordinate +2 (sum of all dimensions of nos. of odd intermediate ordinates) + (Four sum of dimensions all even nos. of inter mediate ordinates)] Cube Diagonal of a cube = 1 Side of cube x 3 Vol. Of a cube = (one side of cube)3 Area of all faces = 6 x (one side)2

53

Diagonal Of A Rectangular solid =  Length2 + Breadth2 + Depth2 Pyramid A pyramid is a solid whose base is a polygon and whose sides are triangles meeting at a common point called vertex Circular Cone A cone is a solid whose base is a circle and whose convex surface tapers uniformly to a point called vertex Volume of a Cone = 1/3 area of base x vertical height. Convex area of cone = r  r2 + h2 Where „r‟ is radius at base and h is vertical height Frusta of a pyramid or cone When a pyramid or cone is cut by plane parallel to the base so as to divide the pyramid in 2 parts the lower part is called a frusta of the pyramid or cone. Volume of frusta of pyramid or cone. = h/3 (A1+A2+A1A2 Where A1 & A2 are the are at top and bottom Note This formula is useful in finding volume of trapezoidal part o column footings SI units and their practical applications In SI units dimensions are expressed in mm, area in mm 2, and bending moment in N mm units. The relation ship in general with metric are as follows 1. 2. 3. 4. 5. 6. 7. 8. 9.

1kg /cm2 1kg cm 1t/m 1Mpa 1Kg (f) 10kg /cm2 0.01kg cm 100kg /m 1 mpa=1Nmm2

= = = = = = = = =

0.1N/mm2 100Nmm 10kN/m 1N/mm2 10N 1N/mm2 1Nmm 1kN/m 0.1020Kg/mm2

54

BRITISH & METRIC UNITS OF LENGTH & CONVERSION FACTORS British Unit 12 Inch = 1 Foot

Metric Unit 1mm =

British to Metric 1”= 25.4mm = 2.54cm 1ft. = 30.48cm = 0.3048mtr.

Metric to British 1mm=0.0397 inch

3 Feet = 1 Yard

10mm = 1cm

220 Yards = 1 10cm=1 decimeter Furlong 8 Furlong = 1M 10dm = 1 meter

1 yard = 0.9144 mtr. 1 furlong = 0.201km

One survey chain 100cm = 1 meter =100 Ft.

1 mile = 1.609km

1 Decimeter = 3.937 = 0.328 feet. 1 Meters =39.37” = 3.281 feet = 1.094 yard 1 deka meter= 32.81 feet = 10.94 Yard 1 Hecto Meter = 328 ft. 1” 1KM=3280 ft. 10 in = 1093.63 Yards. = 4.97 Furlong = 0.621 Miles

1000mm = 1 mtr. 10 mtr. = 1 DM (Deka mtr.)

1 cm= 0.397 Inch

10DM= 1Hecto meter BRITISH & METRIC UNITS FOR AREA British Unit

Metric Units

144Sq. Inch = 1 1 Sq. Mtr. 2 Sq. Foot 10,000cm

=

9 Sq. Ft. =1 Sq. 1 Sq. Yard 100mm2

=

Cm

Conversion British to metric 1” Sq Inch = 6.45 Cm2 = 645.2 mm2 1 Sq. Ft. = 929.0 Cm2 = 0.093 M2 1 Sq. Yard = 0.836 M2

1 Sq Chain=484 1 Sq. sq. Yards Km.=1000,000 Sq. mtrs. 1Acre = 43560 Sq. 1 Sq. Km = 100 1 Acre = 4046.86 Ft. Hectares M2 = 0.4047 Hectors 640Acres = 1 Sq. 1 Sq. Mile Mile an Acre is the = 2.590 Sq. area of a square Kilometers whose side is = 259 Hectors 208.71 Ft. Long = 640 Acres

Conversion Metric to British 1 mm2 = 0.00155 Sq. inch 1 cm2=0.155 Sq. inch

1 Sq. mtr. = 10.76 Sq. Foot 1 Hector = 11959.85 Sq. yard. = 2.470 Acres 1 Sq. Kilometer = 247.10 Acres = 0.3861 Miles2

55

BRITISH & METRIC UNITS FOR VOLUME

British Unit

Metric Units

Conversion British to Conversion Metric metric to British 3 1 Cu ft. = 1728 1000mm =1Cu. Cm 1cu. Inch= 16387 cu. mm 1 cu cm= 0.061 cu cu. Inch or 1 C.C. 1 cu ft=16.387cu. cm inch 1000C/C = 1 Litter 1 Cu. Yard = 27 1000000 Cu. Cm= 1 cu ft. =28317cu. cm 1 cu mtr=35.315 3 Cu. Feet 1M = 0.02832 cu meter cu. ft. = 1.308 cu. 1000 Ltrs= 1M3 = 28.317 Liters Yards. 1 cu. yard = 0.765 cu. Mtr. = 765 Ltrs. Note : 1 Liter of water weight‟s 1 kilogram and is equal to 1000 cu centimeter or CC.

56

WHO STANDARD FOR DRINKING WATER S/N PARAMETERS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 1 2 3 4

(A)PHYSICO- CHEMICAL TESTS Appearance (apparent color ) Color (True color units) Ph at 25”C Conductivity (u.s/cm) Odor Total Suspended Solids (TSS) mg/l) Total Dissolved Solids (TDS) mg/l) Total Hardness (CaCO3), mg/l) Bicarbonates (Hydrogen Carbonate HCO3 mg/l Alkalinity (CaCO3). mg/l Acidity (CaCO3). mg/l Aluminum mg/l Zink (mg/l) Iron (mg/l) Calcium (as Ca2+ mg/l) Magnesium (as mg2+ mg/l) Lead (mg/l) Copper (mg/l) Manganese (mg/l) Chromium (mg/l) Cadmium (mg/l) Nitrate (( NO3) mg/l) Chloride (mg/l) Sulphate (as SO4 2, mg/l) Phosphate( as a PO4 3 , mg/l) Free Chlorine (mg/l) Phenolic Compounds ( as phenol) mg/l (B) MICROBIOLOGICAL TESTS Total plate count (cfu/100ml) Total Coliforms (cfu/100ml) E coli (cfu/100ml)

WHO LIMITS FOR DRINKING WATER Clear and Colorless 15 a4 a4 Odorless a4 1000 a4 NS a4 a4 0.2 5 0.3 a4 a4 0.01 1.0 0.5 0.05 0.03 50 250 250 a4 0.2-0.4 0.009 a4 0 0

Notes: NS = Not Stated; ND = Not Detected A4 Guideline values have not been established by WHO for these parameters because they are not of health concern at levels found in drinking water. Cfu = colony. Forming units; References: (1) WHO (2004) Guidelines for drinking water quality. Vol1 Recommendations 3 rd edition World Health Organization, Geneva. (2) APHA (1998) Standard Methods for the Examination of water and Wastewater 20 th Edition 1998, American public Health Association Washington D.C. USA.

57

PART-2 FABRICATION OF STEEL STRUCTURE

58

FABRICATION OF STEEL STRUCTURES In every industrial shade steel structures are used extensively. Fabrication of steel structure is a specialized branch of structural engineering along with erection of steel structures. For every industry size and shapes of structures are different to suit the particular need of that industry. It may be noted that accuracy and proper shop welding of connections as per fabrication drawings has to be adhered, distortions and deviations are to be kept with in permissible limits of particular standard mentioned on drawings. For achieving these objectives there should be an independent inspection department or inspection engineer/ supervisory staff who should know their job thoroughly and should be allowed to function freely. Since most of the structures involve major shop welding it is advisable to have a welding engineer. The job of welding engineer should include testing of welders, recommendation of welding sequences for long welded structures like built up sections for columns and crane girders etc., he should also be responsible to conduct various types of test like ultrasonic, radiographic, magnetic particle test, dye penetration test etc. on all important joints like butt welded joints provided in the structures. The quality of fabrication is ultimately revealed when structures are erected, in the form of time taken and ease with which erection work proceeds. Fabrication is done either by giving fabrication contract to a firm having a established factory. The factory should have all modern facilities. Like end milling machines, shapers, planners, lathes, pillar drills, compressed air, hydraulic / mechanical press for rolling and straightening of sections, shearing machines, automatic gas cutting machines, profile cutting machine. Plasma cutting machines, automatic and semi automatic welding machines etc. Since fabrication shops are fully equipped the quality is supposed to be of top class but in absence of quality control the out put quality may be as bad as any road side fabricator who has bare minimum required facilities say hand gas cutting set, welding machine and portable drilling machines. The ultimate quality of finished structures depends not only on inspection of finished structures but on proper stage wise inspection during process of fabrication. Another Way is Site Fabrication. In many cases temporary fabrication shops are established near erection site, particularly when fabrication tonnage is of medium magnitude. When higher fabrication tonnage is required four are five fabrication shops are established in the vicinity say 1 to 3 kilometers of plant site. This saves time and cost of transportation of raw materials and finished steel structures to site. Also control over quality can be better by the employer. But since at site facilities like end milling, plasma cutting, profile cutting etc. are difficult to provide for such site fabrication, the quality of fabricated structures has to be compromised to some extent. Further such site fabrication will be delt with. Fabrication shops established at site should be equipped with following facilities

59

A.

Equipment & Machines 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

17. 18. 19. 20. 21. B.

A covered shed of 100 Meter x 20 meter. The floor should have a leveled concrete floor for layout assembling, welding and finishing work of structures. 2 Piller drills stationary machines one capable of drilling 6mm to 25mm dia holes and another for drilling 25 to 56 dia holes. 2 Nos. of automatic gas cutting machines (Pug Cutting Machines). 4 Nos. hand gas cutting set complete with torch, nozzles and 6 meter gas pipes. 4 Nos. hand drill machines capable of drilling holes from 6 to 25mm holes. Out these 2 nos. should be with magnetic base. If machines are pneumatic type than 2 Nos. of air compressors. 1 No. threading machine for making threads on tie rods extra. 1 Shaper or planner machine. 1 No. electrically run hacksaw machines. 2 Nos. Sami automatic welding machines. 4 to 6 Nos. of AC rectifier welding machines. Pedestal grinder 1 No. fixed. Hand grinders 2 Nos. Mechanical screw jacks 3 Nos. 5 to 10T capacity. Hydraulic jacks 5 Nos., 2 Nos. 10T capacity 1 No., 20T capacity 2 Nos. 5Ton capacity. Rolling machine length 5 to 2000 long 3 roller type capable of rolling 4mm to 12mm m.s. plate. Top roller 150mm and 200 dia changeable to be used for straightening of plates and making pipes and gutters from 2 to 4mm sheets. 5 Tons crane pneumatic type tyre mounted for turning of structures and internal shifting of materials. Chain pulley block 2 Nos. one 5T and 10 Ton capacity with pipe tripod stand. Wire ropes slings 10T capacity 2 Nos., 5Ton Capacity 3 Nos. 2 Tons capacity 5 nos. Trailor with tractor 5 to 10 Ton capacity. for transportation of raw materials & structures Heating oven for heating special type of electrodes and flux.

Measuring & marking instruments Steel tapes 50 Meter 2 Nos., 5 Meter 3 Nos., 2 Meter 6 Nos. Vernier calipers : 3 Nos. with least count of 0.1mm Ordinary tong calipers 3 Nos. Markers 5 Nos. to start with Steel right angles 500mm 2 Nos., 300mm 2 Nos. 150mm 5 Nos. Steel scales 1 Meter long 2 Nos., 500mm, 3 Nos. 300mm 5 Nos.

C.

Miscellaneous Items 1. 2. 3. 4. 5. 6. 7. 8.

Steel racks for stacking of angles, channels, sections etc. Wooden sleepers as per actual requirement at least 20 Nos., 2 to 2.5meter long 150mm to 200mm square section. First aid centre with medicines and trained (First Aid) person. Safety items like hand gloves for workers, gas cutters, welders electricians, safety goggles. Safety helmets. These should be in adequate nos. Oxygen cylinders 20 Nos. which should be replaced as soon as empty. D.A. / LPG cylinders 12 Nos. replaceble as soon as these are empty. Nut, bolts, spanners of various sizes as per requirement. Electrical tool box 2 Nos. 60

9. 10. 11. 12. 13. 14. 15. 16. 17.

Wrenches, crow fars. Steel hammers, 10 Kg. – 2 Nos., 5 Kg., 4 Nos., 2 Kg. 3 Nos. 1 Kg, 5 Nos. 100 gram 3 Nos. Welding gauges to measure 6mm, 8mm, 10mm, 12mm & 16mm fillet weld size 4 Nos. Filler gaigues set to measure gaps 0.1mm to 1mm. Welding holders 6 Nos. +2 Nos. spare with welding cables, 10 meter long with each holder. Piano wire 100 meter bundle. Nylon and cotton thread of 100meter length or more. Spring balance to measure weights up to 50 Kg. Electrode of required brand & specification of 2.5mm, 4mm size (adequate no. of cartons containing 2000 pieces for each size to start with).

Here a general over all requirements is mentioned. As per site condition and type of structures to be fabricated, the requirement may vary and must be adjusted to suit situation. After structures are cleared by inspection authorities the structures are to be thoroughly cleaned and given minimum one coal with primer paint or with 1 coat of primer and coat of finishing paint or as per requirement of specifications. This is required to prevent any rusting and weathering of steel during the period of storage. The painted and finished structures should always be stored 150 to 200mm above ground or floor, on wooden sleepers. In order to prevents rusting or pitting and corrosion which starts due to eddy current passing when metals come in contact with ground even if structure have been painted with primer. This phenomena is specially observed in case of mild steel. Again for painting tools and plants like spray panting gums, brushes etc will be required. painting it self is separate part of fabrication which is described only in short. The thickness of paint is mentioned in DFT like 40 DFT or 60 DFT. Which means measurement of paint layer thickness in microns after paint has fully dried (DFT is dry film thickness). For only acid proof paint special primer coat is required just after sand blasting of fabricated structures. For this sand blasting equipment will also be required. Man Power Requirement Man Power required to run a fabrication shop is given below considering 2 shift working. Workshop in charge for over all purpose Shift In charge Structural Inspectors Supervisors Office Assistants Store In Charge Assistant to Store In Charge Welding In Charge Assistant (Welding) Welders Helpers Gas Cutters Helpers Machine Operators Helpers Riggers

-

1 No. 2 Nos. 2 Nos. 6 Nos. 2 Nos. 1 No. 1 No. 1 No. 1 No. 6 Nos. 4 Nos. 4 Nos. 4 Nos. 4 Nos. 4 Nos. 24 Nos.

61

Unskilled Labour First Aid Centre In Charge Electricians Helpers Crane Operator Tractor Trailer Operator Helper Fabrication Filters Helpers

-

10 Nos. 2 Nos. 3 Nos. 3 Nos. 2 Nos. 1 No. 1 No. 4 Nos. 4 Nos.

If supervisors are trained for first aid then first aid assistants are not required out of these 4 groups can be made and each should have Fitter + Helper Gas Cutter + Helper Welder + Helper Riggers Unskilled Labours

= = = = =

2 2 2 4 2

Thus if 4 groups are made these will involve 4 supervisors and 48 skilled and semiskilled workers. One transportation gang with 1 supervisor and 6 rigger should be formed who should be responsible for raw material transportation and internal transportation, crane and tractor trailor with operators and helpers should be under transportation supervisor. In fabrication shop it is general practice that during day shift major marking, and fitting work is done and structures are tack welded. In the evening or night shift major welding is done. Though there is no hard and fast rules but during day welding machines are used for fatking purpose and in the night time all welding machines are available for main welding. The welders can be engaged accordingly. The above strength of skilled and semiskilled work force along with other staff should be able to give 200 to 250 Tons of structures average per month depending upon type of structures. D.

Process of Fabrication

Fabrication of steel structures has following steps. 1. 2. 3. 4. 5. 6. 7.

Transportation of raw materials. Straightening of section and plates. Marking and cutting and assembling of parts by tack welding. Full welding of tacked frames. Cleaning and final inspection. Painting of structures. Dispatching to erection side.

1.

Transportation of Raw Materials. This is the first step of fabrication. During loading, transportation and unloading care should be taken to avoid bending of plates and section by gently handling the section without any jerk or dropping. Various sizes of angles, channels, I sections and various thickness of plates should be stacked separately on racks or on wooden sleepers. Over hanging should be minimum proper intermediate supports at not more than 1 meter distance should be provided to avoid sagging due to self weight. Different grades of steel should be stacked separately with colour painting with different colours for easy identification.

62

2.

Straightening of Sections and Plates It is common that different sections are found bent after transportation, and plates have local dents. These can not be used as it is in fabrication; sections are to be straightened by using screw jacks, or hydraulic jacks. A piece of soft wood should be kept between sections flange or web and jack. This will avoid impression of jack screw on the sections. Some times hammering may be necessary but in this case also a piece of waste steel plate or soft wood should be kept and hammering should be done, in absence hammer marks will come on main sections. These marks become more prominent when structures are painted. Hence direct hammering should be avoided. For straightening of plates if passed through a rolling machine the plates get straightened to a large extent. For local dents, bends, and rolling defects, plates can be inspected. If any rolling defects, excessive pitting is observed such items should not be used. If defect is only at local place these can be used by cutting out such localized piece in consultation with designer.

3.

Marking and Cutting. Before actual marking proper planning of cutting should be decided for this you must have dimensions of different cut pieces available in stock from previous fabrication for various sections and pieces of plates the sizes of sections and plates which are to be made should also be known. As far as possible maximum utilization of cut pieces should be attempted. This is required to keep wastage of steel with in norms of 1.5 to 2%, gusset plate, pack plates can always be made from available cut pieces of plates. For long sections of beams, channels and angles full length sections can be used but here again by providing one splice, long cut pieces can also be used. In short maximum care must be taken to use available cut pieces which should be stacked separately in store. Having planned cutting list marking should be started. In case of marking it should always be kept in mind that built-up sections which are welded for full length, always shrinks in length after welding, which is known as welding shrinkage. Proper allowance in length while marking has to be given. Generally this allowance is given as 1mm/ meter length. Further allowance for gas cutting is also required. while gas cutting either manually or with automatic gas cutting about 1mm thick material is wasted. That is to say if 500 x 1000mm strip is to be cut out from a plate by gas cutting than marking shall be 502 x 1002 mm if all four sides are to be cut. Similarly if 6000mm long plate girder is to made by welding, having flange width 500mm and web depth of 1000. Than the tack welded section should measure 6006mm in length i.e. 6mm margin is given in length of web as well as flanges. Even if section is found ± 1 or 2mm after welding, it will be with in permissible limits or it can be ground easily by grinding machine. For trusses bracing, auxiliary girders, roof girders full scale layout is drawn on leveled platform and from this layout jigs are prepared and from this mother jig further nos. are taken out by tack welding whole frames. It is necessary that mother jig is inspected and checked with practically nil mistakes. It is easy to make further base frames and welding of members with gussets is done to these welded frames various bracing gussets. Cleats etc. are welded as per drawing and different mark nos. are given, use of gigs saves lot of time and labour and is common in all fabrication shops.

E.

Built Up Sections : Built up sections are invariably provided for crane / gantry, beams, heavy columns, single leg or double leg, roof legs etc. the first step involves cutting preparing plates for flanges and web for lengths required as per drawing and preparing tack welded sections and fixing on fixtures with clamps etc. before welding, some important points must be taken care.

63

If there are butt joints in web and flanges, prepare flanges and web independently by providing and fully welding each flange and web separately. The welded joints should be tested by ultrasonic or radio graphically and pass through the recommended test. Individual flange and web should be made perfectly flat and kinks if available should be removed with the help jacks etc. or by indirectly hammering. Slight heating up to 3000C can also be done butt joints of flanges shall be ground flush for a width 25mm on each side from centre to provide proper surface for web to fit correctly with flanges (inside portion). In case of gantry girder the top flange should be ground flush for a distance of 100mm each side of centre of top flange for proper sitting of rail bottom flange. After assembly of flange plates and web plate proper precaution against buckling of web or dropping of flange due to welding must be taken. This can be done by providing temporary stiffeners tack welded with flange & web. Providing temporary stiffeners is possible only in case of manual welding. Never fix end plates before main section is welded. After welding leave girder to cool under atmospheric conditions. Always keep in mind even rain water should not be allowed to drop on hot weld metal. The weld may crack and steel may become hard. After cooling inspect the section for buckling of web and dropping of flange. Wherever above defects are observed, these should be corrected with any of the methods mentioned earlier and inspected. When section is found OK measure its length if bigger than 2mm correct it by grinding and now end plate can be fixed. For welding of plated section sequence as decided by welding engineer should be adhered under supervision otherwise section may distort to an extent that it has to be rejected. The geometry of the section should be checked and necessary rectification where ever required is done. This should be done before individual plated sections are connected with the help of tacking etc. in case of columns. F.

Preparation of Bearing Surfaces / for 100% Contract with Bottom Plate. Over which the Bearing Surface is Resting. In case of main columns section is shown as machined with 100% contract with base plate then the edges of flange and web ends should be preferably cut with automatic gas cutting and grinding the ends should be made smooth in level by checking during the process of grinding. Similarly base plate surface should be plain and should be checked with straight edge if required small elevated portions should be grinded before assembly with main section similar treatment is required on cap plate of crane leg.

G.

Preparation of End Bearing Plate of Crane / Gantry Girder Cut all faces by pug cutting machines giving due margin for gas cutting the bottom side should be ground smooth the horizontal surface should be at right angle. Mark holes and drill as per drawing the reference for marking of centre of holes should always be taken from bearing surface of end plate. The distance from centre of upper surface of top flange and the bearing surface should invariable kept constant as per requirement of drawing. If end plate is ± 2 to 3 mm even than this distance should be maintained and variation should be adjusted at top of end plate. While welding end plate with web and flange always weld with web on both side first and then weld with flange plates. This is necessary to absorb contraction or expansion of end plates during welding. For the same reason end plates are welded with web of gantry girder after the main longitudinal welding of web with flange (4 lines of welding, length wise) plates at top and bottom. For tack welding same electrode should be used which are to be used during full welding.

64

H.

Full Welding of Tacked Structures After structures are tack welded full welding in to be started during welding following care is to be taken. 1.

Use of right type of electrodes as recommended in drawings and specifications. Please remember that for dynamically loaded and statically loaded structures different types of electrodes are specified.

2.

Some electrodes particularly low hydrogen type require preheating to certain temperatures for a particular period which is specified by the manufacturer of electrodes. The recommendations must be strictly followed.

3.

For automatic welding combination of flux and rod as specified should be used as per recommendations of manufacturer.

4.

Only certified welders should be allowed to weld the structures. There are three main categories of welder. a. b. c.

I.

Welder grade 1 : Can weld horizontal, vertical and overhead position. Welder grade 2 : Can weld horizontal and vertical position only. Welder grade 3 : Can weld only in down hand flat position.

5.

During welding a trained welding supervisor should always be present at site and should inspect and guide the welders.

6.

Any welding should be done sequentially as recommended by welding engineer. The welding engineer should also exercise control on work over welding supervisor.

7.

Proper record for special test conducted on butt joints like ultrasonic and gama-ray or x-ray should be maintained by welding engineer.

Controlled Assembly When more numbers say 10 or more of similar profile are to be fabricated, and these are in two or 3 parts. It is necessary that minimum 1 No. from lot of each 10 must be assembled fully on ground and checked for over all accuracy. This is required since during fabrication the same jig is used repeatedly the mother jig may get disturbed, resulting in faulty fabrication in pieces which are fabricated from disturbed jig. The mother jig should also be checked time to time and corrected when ever required. The pieces selected for controlled assembly should be selected at random.

J.

Cleaning and Final Inspection. After full welding of structures mark number. And drawing number. should be written by paint on at least 2 places at right angle to each other for proper and easy identification of structures. All slag deposit on weld burrs in holes or spatters of welding should be removed and inspecting authority should be requested in writing for inspection. Inspector should be independent and should be directly reporting to highest authority of fabrication shop. If any defects are pointed out during inspection these should be immediately attended by rectification, once structures are cleared by inspection structures should be painted with primer or 1 of primer and one coat of finishing paint as per drawings and specifications. 65

Proper care is to be taken in selection of paint. Structures which are exposed to acidic fumes and or corrosive conditions are always painted with anti corrosive. Primers and finishing paints and before applying primer, surface must be cleaned by sand blasting process. K.

Dispatching Structures to Erection Site When erection site is with in vicinity say 2 to 5 Kilometers structures are to be loaded on open trailers. Under mentioned precautions are to be taken 1.

Structures occupy much more space then steel section and hence should be lifted and placed on tailor so that projecting gussets and cleats etc. are not damaged during handling.

2.

Movement during transportation should be at speed not more than 10 to 15 KM/Hr. and should be smooth avoiding sudden breaking and jerks. The transportation should be as per traffic rules and regulation of the place.

3.

Items like trusses, and framed structures like roof girders auxiliary girders or bracing frames should be kept vertical on tailors to avoid bending with proper temporary fixing to avoid any movement during transportation. Loose angles and other sections, loose gusset plates can be loaded horizontally. These are purlins, side runners, loose bracing angles, heavy crane girders and compound columns etc.

Another point which is to be given thought is that the fabrication shop should be asked to supply 10 to 50 litters of primer and finishing paint to erection site. This is because touchup painting at erection site after erection can not be avoided. If for this purpose paint is procured from market by erection agency it always has slight difference in colour shade and when used leaves patches which are distinctly visible at different places where patch work painting is done. If all structures are to be given one coat of finishing paint after erection then fabricator need not supply paint quantity as described above. Permissible deviations in fabrication are given in Annexure-A L

Some Important Points for General Information Welding is universally used in fabrication of structures and hence it is necessary that fabrication engineer has some knowledge about selection of electrodes, defects of welding etc. Though every fabrication drawing always specifies type of electrodes to be used the general information given here will certainly help fabrication engineer and fabricating firm during execution of job.

Electrodes for Welding All electrodes which are proposed to be use for manual arc welding, semi automatic or automatic welding should be approved by consultant/ designer. For this literature of the manufacturer, describing mechanical properties, chemical composition of metal of core of electrode and flux should be submitted along with recommended current type (AC or DC) and amperes, requirement of preheating etc should be submitted to consultant / designer well in advance before starting of fabrication work. Generally structures are divided in 3 groups.

66

Group –A 1.

Statically loaded structures. These include columns, bracings, roof trusses, roof girders, platforms, ladders, stairs, hand railings and various other miscellaneous types of structures, where thickness of plates and sections used are up to 20mm thick, electrodes of rutile type with E6014 class are used.

2.

For all structures mentioned in „1‟ but with plates and sections used are of above 20mm or at the junctions where sections used are less-than 20mm are to be welded with sections of thickness above 20mm thickness, low hydrogen type electrode of E7018 class are used. This type of electrodes always requires preheating in oven before use.

Group-B 1.

Mainly consists of dynamically loaded structures like gantry girders, auxiliary girders, surge girders including cross bracings between gantry girder and auxiliary girder. For all these structures E7018 classes of electrode are generally recommended irrespective of thickness of sections and plates. These are low hydrogen type of electrodes which require backing / heating in oven.

Automatic & Semi Automatic Submerged Arc Welding For automatic Welding the coding is in FXXX-EXXX form. The particulars of wire flux combination literature should be sent to consultant / designer and got approved before it is procured and used in welding of structures. M.

Defects of welding their remedy and Acceptance Common defects of welding are given in Annexure C which is self explanatory.

N.

Advance methods of Inspection of Welds All welds must be inspected by visual inspection with the help of a magnifying glass of x10 power and visual defects should be rectified. In advanced testing gama ray or x ray testing, ultrasonic testing magnetic particle testing, dye penetration testing are involved. For these special training is required and these are conducted by specially trained technicians. All full strength butt welds in structural fabrication should be tested 100% by ultrasonic testing and minimum 10% length tested by ultrasonic method should be tested by gama ray or x ray for keeping record since in ultrasonic test no record is available after testing is over. It can be stated that x ray or gama ray testing is confirmatory test of ultrasonic test. Any defects beyond permissible limits should be rectified. For testing and acceptance standard specified by designer should be followed.

Types of Welded joints These are given and explained in Annexure B enclosed Selection of Steel for Fabrication of Steel Structure Various grades of mild steels are available in market. For general application following points are given. Use of particular type of steel for specific structure is selected and recommended by designer. According to the design needs wieldable and tested quality of mild steel shall only be used and copy of test certificate of manufacturer shall always be obtained from supplier.

67

1.

For all dynamically loaded structures like crane girders, gantry girders, auxiliary and surge girder all sections and plates irrespective of thickness and for statically loaded structures where plates and sections used are above 20mm thickness steel used shall be IS 2062 Fe 410W „C‟ type.

2.

For all statically loaded structures like columns, trusses / rafters, eave and roof girders, side runners and purlins, bracing, tie rods etc. where sections and plates used are 1 to 20mm thick. Steel used shall be of IS2062 FE410 W „B‟ shall be used.

3.

For all miscellaneous structures like hand rails, Chequered platforms, steel covers, rainwater gutters and down comers, ladders and stairs, safety cages etc where sections and plates used are up to 20mm thickness IS2062 FE410 W- „A‟ grade shall be used for items 1 & 2 steel used shall be of killed quality and for item 3 steel used may be of semi killed or killed quality.

Notes : 1. 2.

Mild steel of other international equivalent standards can be used provided its chemical composition and mechanical properties are as mentioned in tables 1 to 3. Specifications mentioned on the drawing shall always govern when ever discrepancy is noticed.

Permissible deviation in fabricated steel structure are given in Annexure C. the limits given may vary from a particular standard, country to country wise and standard mentioned on drawings and specification should always be adhered to, other useful information‟s for fabrication are given in Annexure D. Please note sectional weight and properties are as per Indian Standard. If other than Indian Sections are used then that particular standard to which sections belong should be referred.

68

BOLTS, NUTS & WASHERS Bolts nuts and washers are universal fasteners used for connecting one metallic member to another metallic member either for providing temporary or permanent connection in structural engineering. Special property of this type of connection is that nun of these can be used individually. All the three items are required for providing a proper designed connection at a particular junction of any two structural members. In old time not very long back, Riveting was the only means to provide dependable connection. With development as an alternate to riveting nut, bolt and washers have replaced riveting. Still in some joints riveting is used even now. Experience gained in providing bolted connections in major structures like fridges and buildings has shown that these bolted connections are as dependable as the riveted or welded connection. The major advantages of using bolted connections can be broadly described as below. 1) These are easy to provide then rivets and as such erection time is saved. 2) In bolted connections the nuts can be tightened to a specific torque by use of torque wrenches and thus these are closer to design conditions. 3) When ever structures are to be shifted the various members can be dismantled easily with out damaging original members and can be shifted and used at other location, thus these provide economical advantage over riveted or welded structures. 4) There is no distortion in the fabricated member due to heat applied during welding or riveting and this helps in providing an almost matching profile of fabricated structure to drawing. 5) There is no interlocking of stresses as in case of welded structures where heat for stress release is to be applied. Since there is no interlocked stresses bolted connections can take the full assigned load without affecting factor of safety. BOLTS. There are many types of bolts used in various places main types are as described below. All shanks are necessarily cylindrical. FOUNDATION BOLT. These bolts are used for providing connection between concrete pedestal and base plate of main steel columns or for providing connection to machine frames and concrete foundation. This type of bolts do not have head at one end but other end which goes in concrete is provided l shape or a square plate is welded to increase the grip length end to ensure that when nuts are tightened the bolt does not come out. At other end essentially threads are provided, length of threads depends upon grip length required, thickness of washers and one or two nuts. In addition minimum 2 threads should project out of top nut, after nuts are fully tightened. In general if 5 mm more length is provided to the grip length + thickness of washers and nuts, it will always be sufficient. For foundation bolts the material specification applicable is I S 5624 BOLTS USED FOR MACHINE FOUNDATION. This type of bolts are similar to foundation bolt for columns as described above with a difference that the location is precisely fixed with reference to position and central line / pass line. There are 2 ways of fixing (a) bolts are fixed with the help of template supplied by machine supplier before concreting of raft/machine foundation and are tack welded with reinforcement of raft/concrete block, care has to be taken that the position of bolts is not disturbed during concreting and vibration. Another way is to provide 100 x 100 or 75 x 75 or 150 x 150 square pockets of depth equal to length of bolt + 50 to75mm to provide cushion in raft. The pockets are solid pieces of thermo coal or wooden hollow pockets which are fixed in reinforcement before concreting of raft/ foundation block. These pockets are removed before erection of machines. After erection and alignment of machine these are filled with special epoxy cement grout. This is done in two stages first after 69

erection and alignment of machine the pockets are filled up to half depth and when grout is set, initial tightening of nuts is done and then balance half depth is fillet with grout material. The nuts are further tightened to their full capacity after grout is fully set. It will be noted that when pocket type of arrangement is provided minor adjustment is possible but if bolts are fixed type as in first case no adjustment is possible. There fore in my opinion providing pocket type arrangement for fixing of machine foundation bolt is more practical. Further in fixed type of bolts concreting of raft or machine foundation can not be done till bolts and template are available physically at site. Due to this type of dependency some times there is delay in concreting. However provision of both types is in practice. Further all machine foundation bolts, nuts and washers are generally supplied by the machine supplier. The washers in this case are essentially in round shape, and 2 nuts are provided with every bolt the main nut is thicker and provided just over washer and when this nut is fully tight-end to required torque then another nut above this is provided and tightened, this nut is called lock nut or check nut. The thickness of cheek nut is always less then main nut. The purpose of providing check nut is to prevent any loosening of main nut due to Vibrations produced during running of machine. SHAPES OF BOLT HEAD & NUTS. Generally all bolt heads are integral part of bolt stem and are hexagonal in shape, nuts are also in hexagonal shape but for bolts, used for connecting wooden parts, and nuts used for fixing of roof sheets to purlins are in square shape. Another type of head is counter sunk head which are used where heads are to be kept in flush with top steels surface of base. SHAPE OF WHSHERS. Washer shapes are circular, square or rectangular. Circular shapes are common in connecting bolts in machine foundation and in bolts connecting steel parts. Square and rectangular shapes are provided in foundation bolts of column and crane girder to column cap. Rectangular shapes are provided where common washer is provided for 2 or more foundation bolts of column. Square shapes are also provided when two wooden parts are connected with bolts. SPRING WASHERS. Spring washers are provided where ever there is reversible load (DYNAMICALLY LOODED STRUCTURES) or vibrations from moving loads or from machine operations. The function of spring washer is to prevent nuts from loosening, similar to check nuts. ADDITIONAL ENFORMATION FOR WAHERES Washers are provided one below head of bolt ad second below nut. Thus minimum 2 numbers are required for each bolt. The bolts may be temporary or permanent. In foundation bolts for columns or holding down bolts for crane girders. The size of bolts varies from 20 mm ø to 100 mm ø. In such places washers have to take up the function of transfer of full stresses developed in bolt namely, bearing, stresses tensile stresses, shearing stresses, at all such places nominal thickness of washers as per standard are not sufficient since hole ø in base members like base plate of columns or bottom flange of crane girders are 4 to 6 mm bigger then the size of bolt. At all such places the washers have to provide sufficient area and thickness to cover large gaps around bolt (due to providing 4 to 6 bigger size of hole) and to distribute the pressure on a bigger area. The hole in washer plate is 1.5 mm bigger then the nominal bolt size up the 25 mm ø and 2 mm bigger for bolts above 25 mm ø.

70

SIZE OF WASHERS. Generally in our practice square size washers are provided for column foundation bolts and holding down bolt for crane girders. Dimensions are decided as shown below.

d1 d1

d1

a

d1 a a = 3d1 where d1 = d+1.5 or 2 mm depending upon bolt size as explained above (d is diameter of the bolt) 1.5 d1 from the centre of hole is the guiding factor. THICKNESS OF WASHER PLATE Actual design of thickness of washer plate is a complicated procedure it has been mentioned in “DESIGN OF STEEL STRUCTURES”( by H Gaylord & Charles Gaylord) that because of early local yielding in the plate at the point of contact with the pin (bolt) the stress distribution is so complex as to rule out a satisfactory mathematical solution. The only feasible procedure is to determine design criteria from the study of test results. Accordingly based on 106 test results on pin connected plate were conducted in USA up to the failure limit of test pieces and on the basis of results following conclusions are drown. Stress concentration at the edge of hole had no apparent effect on the ultimate strength of the plate under static loads, since tensile fracture on the net section of the plate at the pin hole did not occur until the average stress on the net section reached the ultimate tensile strength of the steel. Further dishing action which is bulking of the plate beyond pin is anther factor of stability, dishing depends upon ratios of d1/t, a/t , b/t where “d1” is ø of pin hole, and a & b are edge and end distance at the pin hole. It was concluded that if the ratio of net width at the pin hole to thickness of the plate, ranges from about 6 to 10 the member shall be strong enough to resist dishing. The ACISC, AREA and AASHO specifications all agree on a limit of 8 for the ratio of net width at the pin hole to the thickness of the member at the pin. Our national building code gives following clause regarding thickness of washer. CLAUSE 12..3 PART V STRUCTURAL DESIGN SECTION 6 STEEL. “In all cases where the full bearing area of the bolt is to be developed the bolt shall be provided with a washer of sufficient thickness under the nut to avoid any threaded portion of the bolt being with in the thickness or the parts bolted together.” Further hand book of CIVIL ENGINEERING BY KHANNA says in permanent bolted connections washers having thickness less than one quarter of the diameter should not be provided. The washers not less than 6 mm shall be used under the heads and nuts. Now examining AISC, AREA and AASHO. This gives ratio of 8 for net width of washer at the pin to thickness we get.

71

The net width of plate at pin = 3D-D = 2D Thickness of washer t Than 2D/t = 8 or t = D/4 this is 25% of hole ø and is in line with the hand book. On these lines a table is given showing ø of bolt, hole size in base plate / bottom flange of crane girder, washer size and minimum size and thickness of washer for general guidance in annexure A. In this nearest higher size of plate thickness available has been taken. Along with above information of permissible stress in bolts is also given. A list of Indian standards applicable for bolts, nuts washers is given in annex B

72

ANNEXURE A BOLTS

BASE PLATE

WASHERS

S.NO

DIA MM

AREA MM

HOLE ø MM

AREA MM2

HOLE ø MM

AREA MM2

SIZE

MINIMUM THIKNESS IN MM

1

20

315

24

453

21.5

363

65X65

6

2

22

380

26

531

23.5

434

70X70

6

3

25

491

30

707

27

573

80X80

8

4

30

707

36

1019

32

805

90X90

8

5

32

805

38

1135

34

909

100X100

10

6

36

1019

42

1387

38

1135

110X110

10

7

40

1258

46

1663

42

1387

120X120

12

8

48

1811

54

2292

50

1965

145X145

16

9

50

1965

56

2465

52

2125

150X150

16

10

56

2465

62

3021

58

2644

170X170

16

11

60

2830

66

3424

62

3021

180X180

16

12

80

5030

86

5813

82

5285

240X240

22/25

13

100

7860

106

8831

102

8178

300X300

22/25

MAXI`M PERMISSIBLE STRESS IN RIVETS AND BOLTS.

Description of Fasteners (1) Power-driven rivets Hand-driven rivets Close tolerance and turned bolts Bolts in clearance holes

Axial Tension (2) MPa 100 80 120 120

Shear

Bearing

(3) MPa 100 80 100 80

(4) MPa 300 250 300 250

73

ANNEXURE B NO.

DISCRIPTION

I S CODE

1

BOLTS & SCREW AND NUTS dia M5 to M 64 GRADE C.

2

HEX, BOLTS, SCREWS & NUT GRADE A & B M3 TO M64.

3

WASHERS PLAIN.

I S 5369

4

SPRING WASHERS.

I S 3063

5

HEXAGON FIT BOLTS.

I S 3640

6

HIGH TENSILE FRICTION GRIP BOLTS.

I S 3757

7

HIGH TENSILE FRICTION GRIP NUTS.

I S 6623

8

SPECIFICTION FOR HEXGONAL BOLTS FOR STEEL STRUCTURES

I S 6639

9

GENERAL REQUIREMENTI FOR PLAIN WASHER.

I S 5369

10

PLAIN WASHERS WITH OUT SIDE dia MORE THEN 3 TIMES dia OF HOLE.

I S 5370

11

SP FOR TAPERE WASHER FOR CHANNELS.

I S 5372

12

SP FOR TAPERED FOR ISMB.

I S 5374

13

SP FOR FOUNDATION BOLTS.

I S 5624

14

SP FOR HEAVY WASHER FOR STEEL STRUCTURES.

I S 6610

I S 1363 part 1,2,3 I S 1364 part 1,2

74

ANNEXURE-C PERMISSIBLE DEVIATION IN FABRICATION Fabricated structures can not be perfectly made with ±0 tolerance due to reasons of welding, gas cutting, rolling defects in size and straightness of sections and also due to limit of human accuracy. Following deviations are permissible, since inspection is to be done at various stages, the permissible deviation are given in that order. 1.

Maximum permissible gap in built up members after fitting but before welding. Thickness Member

of

Permissible gap Straight Position Curved Portion At edge At 20mm from At edge At 20mm from edge edge Up to and including 0.3mm 0.2mm 1.0mm 0.8mm 20mm Over 20mm 0.3mm 0.2mm 1.5mm 1.2mm The gap should be measured by tiller gauges by the inspector. In case gaps are more, it should be rectified and re-inspected. Welding should be done only after approval by the inspector for different plate thickness, thinner plate shall govern the permissible gap. 2.

For bearing surfaces like base plate to columns cap. Plate to column where machined surface is indicated the above gaps are not permitted. In all such places minimum 80% of the area of contacting surface should have full contact without any gap. In balance 20% of area at scattered places 0.2mm tiller should not be able to enter into the gap. Or just enter i.e. the gap should not be more than 0.2mm.

3.

Gap at splice joint of two joining main member (FG 1) The gap „Q‟ wide „S‟ for rolled section and built up members which are joined either by bolts, or weld through splice cover plates should not be more then as below Depth of main member D Up to 1000mm Above 1000mm

Gaps 1.5mm 3.0mm

75

4.0

Deviation in depth & width of joint For rolled as well as plated section either bolted or welded the deviation permissible in depth and width shall be as below (Fig. 2 & 3) Height „H‟ & width „B‟ of section in mm Upto and including 1000 for main structures Over 1000mm For miscellaneous structures like platforms, galleries, stairs & ladders etc. up to and including 1000mm Over 1000mm

5.0

Deviations in mm 1.00 2.00 2.00

3.00

Gap between splice cover plates and main member

Gap permissible is same as above In welded connection fillet weld size specified in drawing should be increased by 2mm after providing a shims in side the gap at end.

76

6.0

Gap between guset plate and lattice member of rolled section like angle or channel on joint. Gap may be all around either visible at end or at toe or heel of angle the gap should not be more than 2mm. Gap should be packed by providing shims in the gap and weld size should be increased by 2mmall around the angel contact with gusset plate. In case thin section up to 12mm gap should be reduced to 0.2mm. if section thickness is above 12mm and gap can not be reduced then procedure of providing shim and welding may be permitted.

7.0

Out of straight line bending of flanges due to welding in plated sections used as columns, crane girders or built up beams.

i)

At ends or at places where there are bearing stiffener or at places where connections of beams or bracings are there.

At all other places

S

=

S S

= =

B/200 Maximum B/100 Maximum

0.005B

At other places 0.01B

77

7.0(ii) For end plates and end bearing plates of crane girders

8.0

Permissible deviation Δ in length, depth and width of beams and plate girders & open web girders.

78

a.

Depth tolerance

Length tolerance Deviation in span L of truss between end plates / end erection holes of truss / open web girders / plated girders shall be as below

79

When L is under 12 Meters Δ = ± 3mm When L is more 12 Meters Δ = ± L / 2500 Max. up to 5mm Deviation in length of individual member of truss or open web girder Δ = ± 3mm Deviation in length of member with end plates, which are to be inserted between two main members.

Δ = 0 to -2mm Crane girders / gantry girders In all crane girders / gantry girders made out of plates or by combination of rolled section and plates.

80

Deviation in Straightness of girder 1.

When bottom of girder is laid on leveled ground, deviation Y1 in the horizontal plane from straightness of solid web girder shall not exceed 0.001L subject to maximum of 10mm which ever less where L is the length of girder. In case of crane girder the value of Y1 shall be limited to 3mm in 12 meter length of girder.

2.

In the vertical plan no concavity is allowed and the convexity Y2 shall not exceed +5mm

In crane and gantry girders where camber is provided in drawing the deviation from the intended camber at mid length shall not be more than L/1000 or 6mm which ever is greater when measured.

81

3.

Buckling of web The permissible buckling of web of plate girders measured between the top and bottom flanges or between the stiffeners shall be as given below Dimension in mm H Upto 500 Over 500up to 1000 Over 1000

Maximum permissible buckling mm 0.5 1.0 2.0mm

Deviation in the alignment of beams The lateral deviation Δ1 in the alignment of the nodal points of the lattice beams perpendicular to their axial plane measured after the fabrication in the shop or after trial assembly, shall be limited to ± 0.001 L where L is the span of beam subject to maximum of ± 10mm.

82

Flatness of top flange of crane girders Crane girder top flange on a strip of 200mm (100mm on each side of centre of web) or the rail width +20mm shall be made flat and gap between a steel straight edge when placed on top flange shall not be more then max. 1mm. At other places and on bottom flange deviation shall be B/100 or 3mm which ever is minimum.

Web eccentricity In crane girders web eccentricity shall not be more than shown in the sketch.

Crane girder cross section at bearing Squareness of flanges to web

83

Column tolerance on height and straightness The permissible deviation in the heights of the column measured from the bottom of the base plate or support shall be as mentioned below

1.

2.

3.

Overall height L1 Over all height L2

Length in meters Upto and including 10 Over 10 meters

Distance to the top of the All lengths angle cleat from the L1 bottom of cane girder Distance of bottom of crane Up to and including 10 girder to the bottom of the base plate L1 girder to the bottom of the Over 10 base plate L2

Tolerance mm ±5 ±0.0005L subject maximum ±8 ±3

to

±5

±0.0005L Subject Maximum ±8

to

Limit Deviation – Profile of Structures The permissible limit of deviation of the depth D of the section at salient points measured after shop fabrication or after trial assembly at site in their final position shall be as mentioned below

Depth „Y‟ (mm) Upto and including 500 Over 500

Permissible Deviation (mm) ±2 ±0.004 „Y‟ with a maximum of 4

Deviation on dimensions of holes for bolting / riveting 84

Pitch Distance The permissible deviation on pitch distance of holes and distance between the rows of holes unless the holes have been formed to suit the available production facilities shall be ±1 for dynamically loaded structures like gantry girder, surge girders and auxiliary girders. For statically loaded structures like trusses, eaves girders, bracing etc. ± 2mm Dimensions of Drilled Holes – The nominal diameters of drilled holes and permissible deviations on the diameter, perpendicularity, overlapping of holes etc, shall be as specified in Table 7. This does not cover turned and fitted bolts . The permissible deviations in percentage specified in Table refers to the maximum percentage of holes with deviations occurring in a group of holes for this purpose the following shall be considered as group of holes: a. b. c.

Holes made in individual components for erection joints or holes made for connection to individual components , Holes connecting individual bracings, and Holes made in one half of a gusset plate of a joint . Where more than one gusset plate is used the holes between the individual joint shall be taken as separate group of holes.

The maximum number of defective holes in one group when the number of holes in the group exceeds 4 shall be limited to 25 percent. However, when a cross section is taken through the holes the number of defective holes on one side of the cross section shall not be more than 15 percent (see Table). For steel structures of Group B, if the defective holes may be reamed to a bigger diameter and bolts or rivets of the corresponding higher diameter may be used , in exceptional cases and with the approval of the engineer incharge, For steel structures of Group C, if the defective holes are not reamed bolts or rivets with suitable deviations in their dimensions ma be used so as to have a proper fitting of the joint, in exceptional cases and with approval of the engineer incharge, When turned and fitted bolts are used, the holes shall be drilled under size by one mm and after assembly, shall be reamed to a proper size with tolerance + 0.15 mm,-0 mm. Scratches or grooves on the cylindrical surfaces of the drilled holes shall be Table 8.

limited as given in

85

86

TABLE 8 SCRATCHES OR GROOVES ON THE CYLINDRICAL SURFACES OF THE DRILLED HOLES

DEPTH OF

NO. OF HOLES TO WHICH THE PERMISSIBLE LIMITS ARE APPLICABLE

SCRATCH, MAX Group of structure (1)

No. of holes, percent

(2)

(3)

B C B C

25 50 Nil 25

Mm 0.2 0.5

DISTANCE Between Groups of Holes- Deviation in distance between the centres of gravity of any two groups of holes shall not be more than 2mm. Edge Distance Deviation – Edge distance shall not vary from the specified values by more than 1mm for Group B and 1.5mm for group C structures. Note : Group-B:

Steel structures having special characteristics and structures subjected to dynamic loading like crane gantry girders and supporting structures like auxiliary & surge girders etc.

Group-C:

Steel structures like platform, galleries, stairs etc. subjected to static loading.

Edge distance deviation Edge distance shall not vary from the specified value by more than 1mm for B structures and by 1.5mm for group C structures. In situation where specific deviation is not covered IS 7215 shall be followed. Mild steel to be used in fabrication Mild steel of wieldable quality shall only be used for fabrication of structures shall be as below. 1.

For dynamically loaded structures like crane girders, gantry girder auxiliary girders, surge girders. The steel shall be of IS 2062 FE410W „C‟. Wieldable steel of other equivalent standard like ASTM or British Standard or as per code of the country (if available) can also be used provided it has chemical composition and mechanical properties given in the table1. 87

2.

For all statically loaded structures like columns, trusses / rafters, eave girders, purlins, side runners sag rods, columns & roof / rafter bracings rolled sections and plates up to thickness 25mm shall be of IS2062 FE410 W‟ B‟ (killed) shall be used. Sections and plates above 25mm shall be invariable of FE410 w „C‟ killed quality wieldable steel of other standards as mentioned above can be used provided. It has chemical composition and mechanical properties as given in attached table-2.

3.

For miscellaneous structures like hand rails, ladders and stairs, chequered plates, covers, gutters and down comers etc. all plates and sections where thickness of rolled steel sections and plates is maximum up to 20mm. steel of IS2062 FE 410 W „A‟ killed or semi killed shall be used. Mild steel of other equivalent standards as mentioned in point can be used provided it has chemical composition and mechanical properties as mentioned in table 3 attached. However the above is general and over all specification of steel to be used during fabrication and erection of steel structures. If there is any difference in the detailed drawings, the specifications given in the drawings shall govern. The contractor must produce test certificate from producers for steel which is to be used in fabrication of structures. In case of any doubt the owner is free to get additional test carried in government test house or through government recognized test house or private material testing laboratory. In all cases where additional testing has been ordered, if material passes the test successfully the cost of such test shall be borne by the owner and in case of failure the cost shall be borne by the contractor. The contractor shall also remove the entire lot which has failed in test and replace same at his own cost. TABLE-1 Chemical Composition

Percent Maximum Sr. Sample Material No. Designation 1. 2.

Laddle Analysis Product Analysis

Fe 410W „C‟ Killed Fe 410W „C‟ Killed

Mechanical Properties Sr. Material Tensile No. Designation Strength Min. MPa 1. Fe 410W 410 „C‟ Killed

C

Mn

S

0.2

1.5

0.0400

0.0400

0.4

CE Carbon Equivalent Maximum 0.39

0.22

1.55

0.045

0.045

0.43

0.39

Vield Stress Thickness <20 20-40 >40 250

240

230

P

Si

% Elongation Charpy notch Gauge Length Impact Energy J min. 5.56 √50 23 27

Note : The minimum charpoy impact energy shall be guaranteed at any one of the temperature 00C or -200C or – 400C

88

TABLE-2 Chemical Composition Percent Maximum Sr. Sample Material C No. Designation 1. Laddle Fe 410W „B‟ 0.22 Analysis Killed 2. Product Fe 410W „B‟ 0.24 Analysis Killed

Mn

S

P

Si

1.5

0.045

0.045

0.40

1.55

0.05

0.05

0.43

CE Carbon Equivalent 0.41

Mechanical Properties Sr. No.

Material Designation

1.

Fe 410W „B‟ Killed

Tensile Strength Min. MPa 410

Vield Stress Thickness <20 20-40 >40 250

240

230

% Elongation Charpy notch Gauge Length Test J min. 5.56 √50 23 27

Note : Min. charpy V Notch impact energy is to be guarantee at 00C by the manufactures. TABLE-3 Chemical Composition Percent Maximum Sr. Sample Material C No. Designation 1. Laddle Fe 410W „A‟ 0.23 Analysis Killed 2. Product Fe 410W „A‟ 0.25 Analysis Killed or Semikilled

Mn

S

P

Si

1.5

0.050

0.050

0.4

1.55

0.055

0.055

0.43

CE Carbon Equivalent 0.42

Mechanical Properties Sr. No.

Material Designation

1.

Fe 410W „A‟ Killed or Semikilled

Tensile Strength Min. MPa 410

Vield Stress Thickness <20 20-40 >40 250

240

230

% Elongation Charpy Gauge Length notch Test J min. 5.56 √50 23

89

ANNEXURE-B STANDARD V PREPARATION FOR FULL STRENGTH BUTT WELD JOINTS OF PLATES

90

91

NOTES FOR MULTPLE PASS FILLET WELDS: 1. 2. 3.

In multiple pass fillet weld each pass has to cool before next pass of weld is given after removal of slag and should be thoroughly cleaned. For each pass same brand of electrode should be used. First or root run should be given by using smaller size of electrode root and subsequent passes over run can be given by using higher size of electrodes.

NOTES FOR BUTT WELDS: 1. 2. 3. 4. 5. 6. 7.

All burrs and dirt, grease etc. should be cleaned before starting edge preparation. After preparation edge single or double v the edges should be made smooth. Root run should be gauged out by grinder from other side before providing weld. After each run weld should be allowed cool down and then slag over weld should be removed and cleaned by wire brush before depositing subsequent layer of weld. Using of D.C. currant from welding generator or transformer with rectifier gives better results in butt joints. Only approved brand of electrodes should be used and instructions of manufacturer regarding preheating, current & voltage conditions etc. should be strictly followed. All types of electrodes should be stored and used in dry conditions.

92

93

FILLET WELDS EXPLAINED Fillet welds Fillet welds are of 2 types 1) Normal penetration fillet welds The size of normal penetration fillet weld is taken as the minimum leg length of a convex or flat fillet weld.

2)

Deep penetration welds

Deep penetration welds are those welds in which the depth of penetration at the root is 2.4 mm and more beyond the root. The size of deep penetration weld is taken as minimum leg length +2.4 mm is the case of convex or flat fillet weld in case of con cave fillet welds it is taken as 1.41x effective throat thickness +2.4mm In Building structure only normal penetration welds all considered unless specified otherwise . Effective throat thickness of flat or conve fillet welds Angle between fusion faces Factor by which fillet size is multiplied to give throat thickness

60 ‟-90‟

91‟-100‟

101‟-106‟

107‟-113ֹ

114‟-120‟

0.7

0.65

0.60

0.55

0.50

94

Strength of fillet welds

Following figure of a fillet weld will make clear various parts

ℓ Throat thickness is always

√2

The safe load which can be carried by a fillet weld having a leg length ℓ per cm. length is calculated by the formula ℓ / √2 x1x permissible shear stress of a particular grade of steel per cm2 Please note l/√2 x1x cm is the area of shear resistance offered by weld. With above explanation safe load of fillet weld of various sizes which are permissible per cm length are tabulated below. SAFE LOADS INN FILLET WELDS IN KG/CM LENGTH

S.NO 1 2 3 4 5 6 7 8 9

LEG LENGTH mm 4 5 6 8 10 12 16 18 20

THROAT THICKNESS mm 2.83 3.50 4.20 5.60 7.0 8.4 11.3 12.73 14.14

ST43 PERMISSIBLE SHEAR STESS 1150 Kg/Cm2 325 Kg/cm 400 “ 480 “ 648 “ 800 “ 960 “ 1300 “ 1410 “ 1620 “

STEEL GRADES ST50 PERMISSIBLE SHEAR STESS HEA 1600 Kg/Cm2 450 Kg/cm2 560 “ 670 “ 890 “ 1120 “ 1340 “ 1800 “ 2030 “ 2260 “

ST55 PERMISSIBLE SHEAR STESS 1950 Kg/Cm2 550 Kg/cm2 680 “ 810 “ 1090 “ 1360 “ 1630 “ 2200 “ 2480 “ 2750 “

95

NOTES OF FILLET WELDS a. Angle between fusion faces Such fillet welds which are connecting parts which are forming an angle more than 120‟ or less than 60‟ should not be relied upon to transmit calculated loads at the full working stresses unless permitted to do so by the standard for the particular application. This is because in the cases mentioned above full penetration to the root is difficult. b. End Returns. Fillet welds terminating at the ends or sides of parts or members should be returned continuously around the corners for a distance not less than twice the size of weld. This is applicable to side fillet welds connecting brackets, seats and similar connections at the tension side of such connections. c. Size of fillet weld at toe of rolled section. When a fillet weld is applied to a rounded toe of rolled section the specified size of weld should generally not exceed ¾ th (75%)of the thickness of the section at toe. d. Stress in fillet weld The stress in fillet weld must not exceed the permissible shear stress in the parent metal for example if steel 50 is welded. With steel 55 the permissible shear stress should not exceed 1600 kg/ cm2 When steels of different grades of are welded permissible shear stress of lower grade of steel shall govern the permissible shear stress in weld. For example if weld is joining steel 43 and steel 50 (two different grades of steel ) then permissible shear stress in fillet weld should not exceed 1150kg/cm2 which is the permissible shear stress for steel 43 grade of steal. MINIMUM SIZE OF RUN It is always better to use minimum of runs of weld for achieving a particular size of weld. The reason being that with every run of weld parent metal in the vicinity of weld bead is subjected to heating to about 1000*c and cooling This in turn induces locking of stresses and causes metallurgical changes in parent metal and cracks may appear in the weld bead. When the thicker part more than 50 mm are to be welded special precautions are required to be taken as per recommendations of the manufacturer of the electrode being used. To avoid risk of cracking the minimum size of single run fillet weld by a manual process using electrodes of class 2 or 3 as per B.S standard (B.S 1719, part) shall be as specified below. Minimum size of single run fillet weld for manual welding (using electrodes of class 2 or 3 to B.S 1719 Part 1 THICKNESS OF THICKER PART Over mm 9 16 30 and above

Up to and including mm 16 30

MINIMUM SIZE OF SINGLE RUN FILLET WELD mm.

5 6 8

96

LAPJOINT WITH FILLET WELDS

EFFECTIVE LENGTH The effective length of fillet weld is always = L- 2t where “t” is the fillet size of weld. END RETURN WELDS The fillet welds should be returned wherever possible and should not be less than 2x “t” where t is the size of fillet weld. Over lap

In a lap joint length of over lap should not be less than 5x T1 or T2 Which ever is less?

SIDE FILLET WELD In any lap joint made by side or longitudinal fillet weld the length of each fillet weld “L” should not be less than perpendicular distance between them i.e. L. should be equal to minimum “B” or more similarly “B” should be maximum 16 x T1 or T2 which ever is less . In case where “B” exceeds more than 16 T1 or T2 which ever is less than additional plug weld or slot weld is provided to prevent buckling or separation of the parts. This is made clear in the following sketch.

The situation will generally arise in welded channels, like ISMC 300 and ISMC 400 or when splice with cover plates are to be provided on web and flanges of built up sections of cols and beams.

97

ANNEXURE-D STEEL STRUCTURES

Useful information for steel structures. Steel structures are an integrated part of any industrial shed. Following information is for guidance; generally fabrication is done in workshops which are equipped with machines for cutting, grinding fitting and welding. These fabricated structures are transported to site and erected. Some times fabrication of structure is also done at site where a site engineer is supposed to exercise control during fabrication. After erection and alignment of structures final welding and tightening of bolts as specified by supplier of the structures is done. The alignment scheme should be made clearly mentioning deviations in both X & Y direction. The permissible limits for these deviations are supplied by the manufacturers. In case these are not supplied relevant IS standards should be followed. Before final acceptance a joint protocol duly signed by all concerned parties should be made for record. This is required to avoid confusion in case of any problem arising. During erection also some drilling, gas cutting, grinding and welding is required. Hole Making: No hole should be allowed to be gas cut and it should be drilled only in any steel structure or its member. Gas Cutting: Gas cutting of steel sections or plates if required is permissible provided after gas cutting, burrs on gas cut edges are properly cleaned and ground smooth. Welding: Electric arc welding is done after erection and alignment of structures. The weld bead after cooling should be cleaned by removal of slag by pointed hammer and wire brush, water should never be poured on hot weld, it may result in inducing cracks in weld metal. Edge Distance of Holes Sr. Dia. Of Holes No. mm 1. 13.5 and Below 2. 15.5 3. 17.5 4. 19.5 5. 21.5 6. 23.5 7. 25.5 8. 29.0 9. 32.0 10. 35.0

Distance from Centre of hole to shearing or flame cut edge 19 25 29 32 32 38 44 51 57 60

Distance to rolled or machine flame cut sawn or planned edge 17 22 25 29 29 32 38 44 51 57

As a thumb rule keep a distance of one diameter distance between edge of hole and edge of plate. Nuts & Washers 2 washers one below head of bolt and one below nut are provided and then nuts are tightened. Lock Nuts or Check Nuts Where there are vibrations and reversal of stresses are occurring lock nuts or check nuts must be provided for preventing nuts getting loose. Some of the places are, holding down bolts of crane girders and foundation bolts of main steel columns. Some places special spring washers are also prescribed to prevent loosening like rail fixing bolts. Tapered Washers. In side surfaces of channel and rolled sections are tapered and at all such places tapered washers are provided below bolt heads / nuts in order to provide a flat surfaces for proper distribution of tightening pressure. Painting of structures Generally 1 Coat of primer and one finishing coat of final paint is given is shop before dispatch to site and one coat of finishing paint is given after erection and alignment.

98

There are some surfaces of structures, which do not remain exposed after erection, and as such second coat of paint cannot be given on these surfaces. All such surfaces must be given second coat of finishing paint before structures are lifted for erection, example of such surfaces are : 1. 2. 3.

Outer faces end plates of crane girder‟s. Purlins top surfaces on which sheeting will rest. Contact surfaces of 2 members like surface of side runner, which passes over col. Flanges or crossing surface of bracings. These are few examples where if prior to erection finishing paint coat is missed, then it can not be painted until members are separated which is practically impossible after alignment.

Painting Thickness Painting thickness is often measured in microns and generally mentioned as microns DFT, Which means microns ON Dry Film Thickness. After final paint is made the thickness is given as 30 or 50 to 80 DFT, which means 30 or 50 or 80 microns thickness of dry film. The thickness varies as per site conditions and is generally mentioned by the manufacturer. WEIGHS OF STEEL 2 0.7843 KG/CM PER METER Thick in mm 3.15

Black Sheets B.G. Wt. Per Sq. Meter in Kg. 10 24.70

Plates Thickness in mm 5

Wt. Per Sq. meter in Kg. 39.2

Chequered Plates Thickness Wt. Per Sq. in mm Meter in Kg. 7 61.1

2.50

12

19.61

7

55.0

10

84.6

2.00

14

15.69

10

78.5

12

100.3

1.66

16

12.55

12

94.2

1.25

18

9.80

14

109.9

1.00

20

7.84

16

125.6

0.80

22

6.27

18

141.3

0.63

24

4.94

20

157.0

0.50

26

3.91

22

172.7

0.44

28

3.10

25

196.2

FLAT IRON – WEIGHT IN KG. PER METER 2 0.7834 KG/CM PER METER OR 1 CFT OF STEEL = 490 LBS Thickness In mm Width In mm

5

5.5

6

7

8

10

11

12

14

16

12

0.5

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.3

1.5

16

0.6

0.7

0.8

0.9

1.0

1.3

1.4

1.5

1.8

2.0

20

0.8

0.9

0.0

1.1

1.3

1.6

1.7

1.9

2.2

2.5

25

1.0

1.1

1.2

1.4

1.6

2.0

2.2

2.4

2.7

3.1

32

1.3

1.4

1.5

1.8

2.0

2.5

2.8

3.0

3.5

4.0

40

1.6

1.7

1.9

2.2

2.5

3.1

3.5

3.8

4.4

5.0

50

2.0

2.2

2.4

2.7

3.1

3.9

4.3

4.7

5.5

6.3

63

2.5

2.7

3.0

3.5

4.0

4.9

5.4

5.9

5.9

7.9

80

3.1

3.5

3.8

4.4

5.0

6.3

6.9

7.5

8.8

10.0

100

3.9

4.3

4.7

5.5

6.3

7.8

8.6

9.4

11.0

12.6

125

4.9

5.4

5.9

6.9

7.8

9.8

10.8

11.8

13.7

15.7

160

6.3

6.9

7.5

8.8

10.0

12.6

13.8

15.1

17.6

20.1

200

7.8

8.6

9.4

11.0

12.6

15.7

17.3

18.8

22.0

25.1

250

9.8

10.8

11.8

13.7

15.7

19.6

21.6

23.6

27.5

31.4

99

SQUARE AND ROUND BARS 2 0.7843 KG/CM PER METER OR 1 CFT OF STEEL = 490 LBS Diameter or width mm 5.0

Weight per meter  Kg  Kg 0.20 0.15

Sectional Area  Cm2  Cm2 0.25 0.20

Perimeter  Cm  Cm 2.0 1.57

5.5

0.24

0.19

0.30

0.24

2.2

1.73

6.0

0.28

0.22

0.36

0.28

2.4

1.88

7.0

0.38

0.30

0.49

0.38

2.8

2.20

8.0

0.50

0.39

0.64

0.50

3.2

3.51

9.0

0.64

0.50

0.81

0.64

3.6

2.83

10

0.78

0.62

1.00

0.79

4.0

3.14

11

0.95

0.75

1.21

0.95

4.4

3.46

12

1.13

0.89

1.44

1.13

4.8

3.77

14

1.54

1.21

1.96

1.54

5.6

4.40

16

2.01

1.58

2.56

2.01

6.4

5.03

18

2.54

2.00

3.24

2.54

7.2

5.65

20

3.14

2.47

4.00

3.14

8.0

6.28

22

3.80

2.98

4.84

3.80

8.8

6.91

25

4.91

3.85

6.25

4.91

10.0

7.85

28

6.15

4.83

7.84

6.16

11.2

8.80

32

8.04

6.31

10.24

8.04

12.8

10.05

36

10.17

7.99

12.96

10.18

14.4

11.31

40

12.56

9.86

16.00

12.57

16.0

12.57

45

15.90

12.49

20.25

15.90

18.0

14.14

50

19.62

15.41

25.00

19.64

20.0

15.71

56

24.62

19.34

31.36

24.63

22.4

17.59

63

31.16

24.47

39.69

31.17

25.2

19.79

71

39.57

31.08

50.41

39.59

28.4

22.31

80

50.24

39.46

64.00

50.27

32.0

25.13

100

ROLLED STEEL BEAMS Designation

DIMENSIONS Sectional Depth of Area Section a cm2 h mm 9.01 150

Width of Flange b mm 50

Thick. of Flange tf mm 4.6

Thick. of Web tw mm 3.0

Moments of Inertia

PROPERTIES Radii of Gyration

lxx cm4 322.1

lyy cm4 9.2

rxx cm 5.98

ryy cm 1.01

zxx cm3 42.9

zxx cm3 3.7

ISJB

150

Weight Per Meter W Kg. 7.1

Moduli of Section

ISJB

175

8.1

10.28

175

50

4.8

3.2

479.3

9.7

6.83

0.97

54.8

3.9

ISJB

200

9.9

12.64

200

60

5.0

3.4

780.7

17.3

7.86

1.17

78.1

5.8

ISJB

225

12.8

16.28

225

80

5.0

3.7

1308.2

40.5

8.97

1.58

116.3

10.1

ISLB

75

6.1

7.71

75

50

5.0

3.7

72.7

10.0

3.07

1.14

19.4

4.1

ISLB

100

8.0

10.21

100

50

6.4

4.0

168.0

12.7

4.06

1.12

33.6

5.1

ISLB

125

11.9

15.12

125

75

6.5

4.4

406.8

43.4

5.19

1.69

65.1

11.6

ISLB

150

14.2

18.08

150

80

6.8

4.8

688.2

55.2

6.17

1.75

91.8

13.8

ISLB

175

26.7

21.30

175

90

6.9

5.1

1096.2

79.6

7.17

1.93

125.3

17.7

ISLB

200

19.8

25.27

200

100

7.3

5.4

1696.6

115.4

8.19

2.13

169.7

23.1

ISLB

225

23.5

29.92

225

100

8.6

5.8

2501.9

112.7

9.15

1.94

222.4

22.5

ISLB

250

27.9

35.53

250

125

8.2

6.1

3717.8

193.4

10.23

2.33

297.4

30.9

ISLB

275

33.0

42.02

275

140

8.8

6.4

5375.3

287.0

11.31

2.61

392.4

41.0

ISLB

300

37.7

48.08

300

150

9.4

6.7

7332.9

376.2

12.35

2.80

488.9

50.2

ISLB

325

43.1

24.90

325

165

9.8

7.0

9874.6

510.8

13.41

3.05

607.7

61.9

ISLB

350

49.5

63.01

350

165

11.4

7.4

13158.3

631.9

14.45

3.17

751.9

76.6

ISLB

400

56.9

72.43

400

165

12.5

8.0

19306.3

716.4

16.33

3.15

965.3

80.8

JSLB

450

65.3

83.14

450

170

13.4

8.6

27536.1

853.0

18.20

3.20

1223.8

160.4

ISLB

500

75.0

95.50

500

180

14.1

9.2

38579.0

1063.9

20.10

3.34

1543.2

118.2

ISLB

550

86.3

109.97

550

190

15.0

9.9

53161.6

1335.1

21.99

3.48

1933.2

140.5

ISLB

600

99.5

126.69

600

210

15.5

10.5

72867.6

1821.9

23.98

3.79

2428.9

173.5

ISMB

100

11.5

14.60

100

75

7.2

4.0

257.5

40.8

4.20

1.67

51.5

10.9

ISMB

125

13.0

16.60

125

75

7.6

4.4

449.0

43.7

5.20

1.62

71.8

11.7

ISMB

150

14.9

19.00

150

80

7.6

4.8

726.4

52.6

6.18

1.66

96.6

13.1

ISMB

175

19.3

24.62

175

90

8.6

5.5

1272.0

85.0

7.19

1.86

145.4

18.9

ISMB

200

25.4

32.3

200

100

10.8

5.7

2235.4

150.0

8.32

2.15

223.5

30.0

ISMB

225

31.2

39.72

225

110

11.8

6.5

3441.8

218.3

9.31

2.34

306.9

39.7

ISMB

250

37.3

47.35

250

125

12.5

6.9

5131.6

334.5

10.39

2.65

410.5

58.5

ISMB

300

44.2

56.26

300

140

12.4

7.5

8603.6

483.9

12.37

2.84

573.6

64.8

ISMB

350

52.4

66.71

350

140

14.2

8.1

13630.3

537.7

14.29

2.84

778.9

76.8

ISMB

400

61.6

78.46

400

140

16.0

8.9

20458.4

422.1

16.15

2.82

1022.9

88.9

ISMB

450

72.4

92.27

450

150

17.4

9.4

30390.8

834.0

18.15

3.01

1350.7

111.2

ISMB

500

86.9

110.74

500

180

17.2

10.2

45218.3

1369.8

20.21

3.52

1808.7

152.2

ISMB

550

103.7

132.11

550

190

19.3

11.2

64893.6

1833.8

22.16

3.73

2359.8

193.0

ISMB

600

122.6

256.21

600

210

20.8

12.0

91813.0

2651.0

24.24

4.12

3060.4

252.5

ISWB

150

17.0

21.67

150

100

7.5

5.4

889.1

94.8

6.22

2.09

111.9

19.0

101

ROLLED STEEL CHANNELS Dimensions Designation

Properties

ISJC

Weight per meter W kg 100 5.8

Section Area a cm2 7.41

Depth of Section h mm 100

Width of Flange b mm 45

Thick. of Flange tf mm 5.1

Thick. of Web tw mm 3.0

Center of Gravity

ISJC

125

7.9

10.07

125

50

6.6

3.0

1.64

270.0

25.7

5.18

1.60

43.2

7.6

ISJC

150

9.9

12.65

150

55

6.9

3.6

1.66

471.1

37.9

6.10

1.73

62.8

9.9

ISJC

175

11.2

14.24

175

60

6.9

3.6

1.75

719.9

50.5

7.11

1.88

82.3

11.9

ISLC

200

13.9

17.77

200

70

7.1

4.1

1.97

1161.2

84.2

8.08

2.18

116.1

16.7

ISLC

75

5.7

7.26

75

40

6.0

3.7

1.35

66.1

11.5

3.02

1.26

17.6

4.3

ISJC

100

7.9

10.02

100

50

6.4

4.0

1.62

164.7

24.8

4.06

1.57

32.9

7.3

ISLC

125

10.7

13.67

125

65

6.6

4.4

2.04

356.8

57.2

5.11

2.05

57.1

12.8

ISLC

150

14.4

18.36

150

75

7.8

4.8

2.38

697.2

103.2

6.16

2.37

93.0

20.2

ISLC

175

17.6

22.40

175

75

9.5

5.1

2.40

1148.4

126.5

7.16

2.38

131.3

24.8

ISLC

200

20.6

26.22

200

75

10.8

5.5

2.35

1725.5

146.9

8.11

2.37

172.6

28.5

ISLC

225

24.0

30.53

225

90

10.2

5.8

2.46

2547.9

209.5

9.14

2.62

226.5

32.0

ISLC

250

28.0

35.51

250

100

10.7

6.1

2.70

3687.9

298.4

10.17

2.89

295.0

40.9

ISLC

300

33.1

42.67

300

100

11.6

6.7

2.55

6047.9

346.0

11.98

2.87

403.2

46.4

ISLC

350

38.8

49.14

350

100

12.5

7.4

2.41

9312.6

394.6

13.72

2.82

532.1

52.0

ISLC

400

45.7

58.25

400

100

14.0

8.0

2.36

13989.5

460.4

15.50

2.81

699.5

60.2

ISMC

75

6.8

8.67

75

40

7.3

4.4

1.31

76.0

12.6

2.96

1.21

20.3

4.7

ISMC

100

9.2

11.70

100

50

7.5

4.7

1.53

186.7

25.9

4.00

1.49

37.3

7.5

ISMC

125

12.7

16.19

125

65

8.1

5.0

1.94

416.4

59.9

5.07

1.92

66.6

13.0

ISMC

150

16.4

20.88

150

75

9.0

5.4

2.22

779.4

102.3

6.11

2.21

103.9

19.4

ISMC

175

19.1

24.38

175

75

10.2

5.7

2.20

1223.3

121.0

7.08

2.23

139.8

22.8

ISMC

200

22.1

18.21

200

75

11.4

6.1

2.17

1819.3

140.4

8.03

2.23

181.9

26.3

ISMC

225

25.9

33.01

225

80

12.4

6.4

2.30

2694.6

187.2

2.03

2.38

239.5

32.8

ISMC

250

30.4

38.67

250

80

14.1

7.1

2.30

3816.8

219.1

9.94

2.38

305.3

38.4

ISMC

300

35.8

45.64

300

90

13.6

7.6

2.36

6362.6

310.8

11.81

2.61

424.2

46.8

ISMC

350

42.1

53.66

350

100

13.5

8.1

2.44

10008.0

430.6

13.66

2.83

571.9

57.0

ISMC

400

49.4

62.93

400

100

15.3

8.6

2.42

15382.8

504.8

15.48

2.83

754.1

66.6

1.40

Moments of inertia lxx cm4 lyy cm4 123.8 14.9

Radii of Gyration

Moduli of section

rxx cm 4.09

ryy cm 1.42

zxx cm3 24.8

zyy cm3 4.8

102

ROLLED STEEL EQUAL ANGLES Dimensions

Properties

Designation

Size A x B mm

Thick. t mm

Sectional Area a cm2

Weight per meter w kg

Moduli of Section Zxx=Zyy Cm3 Cm2

Designation

Size AxB mm

Thick. t mm

Sectional Area a cm2

Weight per meter w kg

ISA

20 x 20

3.0

1.12

0.9

0.3

ISA

70 x 70

5.0

6.77

5.3

Moduli of Section Zxx=Zyy Cm3 6.3

4.0

1.45

1.1

0.4

6.0

8.06

6.3

7.3

3.0

1.41

1.1

0.4

8.0

10.58

8.3

9.5

4.0

1.84

1.4

0.6

10.0

13.02

10.2

11.7

5.0

2.25

1.8

0.7

5.0

7.27

5.7

7.1

3.0

1.73

1.4

0.6

6.0

8.66

6.8

8.4

4.0

2.26

1.8

0.8

8.0

11.38

8.9

11.0

5.0

2.77

2.2

1.0

10.0

14.02

11.0

13.5

3.0

2.03

1.6

0.9

6.0

9.29

7.3

9.6

4.0

2.66

2.1

1.2

8.0

12.21

9.6

12.6

5.0

3.27

2.6

1.4

10.0

15.05

11.8

15.5

6.0

3.86

3.0

1.7

12.0

17.81

14.0

18.3

3.0

2.34

1.8

1.2

6.0

10.47

8.2

12.2

4.0

3.07

2.4

1.6

8.0

13.79

10.8

16.0

5.0

3.78

3.0

1.9

10.0

17.03

13.4

19.8

6.0

4.47

3.5

2.3

12.0

20.19

15.8

23.3

3.0

2.64

2.1

1.5

6.0

11.67

9.2

15.2

4.0

3.47

2.7

2.0

8.0

15.39

12.1

20.2

5.0

4.28

3.4

2.5

10.0

19.03

14.9

24.2

6.0

5.07

4.0

2.9

12.0

22.59

17.7

29.2

3.0

2.95

2.3

1.9

8.0

17.02

13.4

24.4

4.0

3.88

3.0

2.5

10.0

21.06

16.5

30.1

5.0

4.79

3.8

3.1

12.0

25.02

19.6

35.7

6.0

5.68

4.5

3.6

15.0

30.81

24.2

43.7

5.0

5.27

4.1

3.7

8.0

20.22

15.9

34.5

6.0

6.26

4.9

4.4

10.0

25.06

19.7

42.7

ISA

ISA

ISA

ISA

ISA

ISA

ISA

ISA

ISA

25 x 25

30 x 30

35 x 35

40 x 40

45 x 45

50 x 50

55 x 55

60 x 60

65 x 65

ISA 75 x 75 ISA

ISA

ISA

ISA

ISA

ISA

80 x 80

90 x 90

100 x 100

110 x 110

130 x 130

8.0

8.18

6.4

5.7

12.0

29.82

23.4

50.7

10.0

10.02

7.9

7.0

15.0

36.81

28.9

62.3

5.0

5.75

4.5

4.4

10.0

29.03

22.8

56.9

6.0

6.84

5.4

5.2

12.0

34.59

27.2

67.7

8.0

8.96

7.0

6.8

15.0

42.78

33.6

83.5

10.0

11.00

8.6

8.4

18.0

50.79

39.9

98.7

5.0

6.25

4.9

5.2

12.0

46.61

36.6

122.2

6.0

7.44

5.8

6.2

15.0

57.80

45.4

151.4

8.0

9.76

7.7

8.1

18.0

58.81

54.0

179.9

10.0

12.00

9.4

9.9

25.0

93.80

73.6

243.3

ISA

ISA

150 x 150

200 x 200

103

ROLLED STEEL UNEQUAL ANGLES Dimensions

Properties

Designation

Size AxB mm

Thick. t mm

Sectional Area a cm2

Weight per meter w kg

ISA

30 x 20

3.0

1.41

1.1

0.6

0.3

4.0

1.84

1.4

0.8

5.0

2.25

1.8

3.0

1.88

4.0

ISA

ISA

ISA

ISA

ISA

ISA

ISA

ISA

40 x 25

45 x 30

50 x 30

60 x 40

65 x 45

70 x 45

75 x 50

80 x 50

Moduli of Section Zxx & Zyy Cm3 Cm2

Designation

Size A x B mm

Thick. t mm

Sectional Area a cm2

Weight per meter w kg

ISA

90 x 60

6.0

8.65

6.8

11.5

5.5

0.4

8.0

11.37

8.9

15.1

7.2

1.0

0.4

10.0

14.01

11.0

18.6

8.8

1.5

1.1

0.5

12.0

16.57

13.0

22.0

10.03

2.46

1.9

1.4

0.6

6.0

9.55

7.5

14.2

6.4

5.0

3.02

2.4

1.8

0.7

8.0

12.57

9.9

18.7

8.5

6.0

3.56

2.8

2.1

0.9

10.0

15.51

12.2

23.1

10.4

3.0

2.18

1.7

1.4

0.7

6.0

10.14

8.0

14.4

8.5

4.0

2.86

2.2

1.9

0.9

8.0

13.36

10.5

19.1

11.2

5.0

3.52

2.8

2.3

1.1

10.0

16.50

13.0

23.6

13.8

6.0

4.16

3.3

2.7

1.3

12.0

19.56

15.4

27.9

16.3

3.0

2.34

1.8

1.7

0.7

6.0

11.66

9.2

22.2

8.7

4.0

3.07

2.4

2.3

0.9

8.0

15.38

12.1

29.4

11.5

5.0

3.78

3.0

2.8

1.1

10.0

19.02

14.9

36.3

14.2

6.0

4.47

3.5

3.4

1.3

6.0

12.86

10.1

23.1

14.0

5.0

4.76

3.7

4.2

2.0

8.0

16.98

13.3

30.6

18.5

6.0

5.65

4.4

5.0

2.3

10.0

21.02

16.5

37.8

22.9

8.0

7.37

5.8

6.5

3.0

12.0

24.98

19.6

44.8

27.1

5.0

5.26

4.1

5.0

2.5

8.0

17.42

13.7

41.7

11.8

6.0

6.25

4.9

5.9

3.0

10.0

21.56

16.9

51.6

14.5

8.0

8.17

6.4

7.7

3.9

12.0

25.62

20.1

61.2

17.1

5.0

5.52

4.3

5.7

2.5

8.0

20.58

16.2

44.2

23.2

6.0

6.56

5.2

6.8

3.0

10.0

25.52

20.0

54.9

33.8

8.0

8.58

6.7

8.9

3.9

12.0

30.38

23.8

65.3

40.2

10.0

10.52

8.3

10.9

4.8

15.0

37.52

29.5

80.4

49.2

5.0

6.02

4.7

6.7

3.2

10.0

29.03

22.8

92.8

26.2

6.0

7.16

5.6

8.0

3.8

12.0

34.59

27.2

110.6

31.8

8.0

9.38

7.4

10.4

4.9

15.0

42.78

33.6

136.5

38.3

10.0

11.52

9.0

12.7

6.0

10.0

34.00

26.7

98.3

58.3

5.0

6.27

4.9

7.5

3.2

12.0

40.56

31.8

117.4

69.6

6.0

7.46

5.9

9.0

3.8

15.0

50.25

39.4

145.4

86.0

8.0

9.78

7.7

11.7

4.9

18.0

59.76

46.9

172.5

101.8

10.0

12.02

9.4

14.4

6.0

ISA

ISA

ISA

ISA

ISA

ISA

ISA

ISA

100 x 65

100 x 75

125 x 75

125 x 95

150 x 75

150 x 115

200 x 100

200 x 150

Moduli of Section Zxx & Zyy Cm3

104

WIND VELOCITY AND PRESSURE AT VARIOUS EXPOSED HEIGHTS Height of Exposed Surface Above Mean Retarding Surface (m)

Horizontal Wind Velocity (km/hr)

Horizontal Pressure 2 (kg/m )

0

80

40

3

96

58

6

108

73

9

115

85

12

123

98

15

128

105

18

133

112

21

137

120

24

141

127

27

144

133

30

147

141

38

155

151

46

160

166

53

165

175

61

169

185

76

175

200

92

181

210

107

186

224

122

191

234

105

STANDARD SPLICE JOINT FOR ISMB’S (IS 808 1957) USED AS COLUMNS FOR AXIAL LOAD Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

Mark ISMB-100 ISMB-125 ISMB-150 ISMB-175 ISMB-200 ISMB-225 ISMB-250 ISMB-300 ISMB-350 ISMB-400 ISMB-450 ISMB-500 ISMB-550 ISMB-600

A 40 65 75 90 110 120 130 170 220 270 310 340 365 400

B 50 75 85 125 130 140 170 230 230 235 245 310 355 375

Web Cover Plate (Both Face) C D E T 25 200 25 6 25 250 25 6 25 270 25 6 25 350 25 8 50 360 25 8 50 380 25 8 50 440 25 8 50 560 25 8 60 560 25 8 60 620 50 10 60 640 50 10 60 770 50 10 60 860 50 12 60 900 50 12

Weld S1 4 4 5 5 5 6 6 6 8 8 10 10 10 12

Flange Cover Plate bxs Weld S2 L 90x8 6 340 100x8 6 360 100x8 6 370 110x10 6 450 120x12 6 590 140x12 6 670 150x14 6 790 170x14 8 810 170x14 8 860 170x16 10 890 180x18 10 920 210x18 10 920 220x20 12 950 240x22 12 1065

106

STANDARD SPLICE JOINT FOR ISMB’S USED AS BEAMS Sr. No.

Mark

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

ISMB-100 ISMB-125 ISMB-150 ISMB-175 ISMB-200 ISMB-225 ISMB-250 ISMB-300 ISMB-350 ISMB-400 ISMB-450 ISMB-500 ISMB-550 ISMB-600

Flange Cover Plate Section Length b1 x s1 L1 85 x 8 300 100 x 8 320 100 x 8 350 110 x 10 400 120 x 12 440 140 x 12 550 150 x 14 600 170 x 14 700 170 x 16 720 190 x 16 750 190 x 18 750 210 x 18 800 220 x 20 800 240 x 22 900

Web Cover Plate (Both Face) Section Length b2 x s2 L2 65 x 6 70 80 x 6 100 80 x 6 120 100 x 6 140 100 x 6 160 100 x 8 190 120 x 8 210 120 x 10 240 120 x 10 300 120 x 10 330 120 x 10 380 120 x 12 420 120 x 12 470 150 x 12 510

Weld h 6 6 6 6 6 6 6 8 8 10 10 10 12 12

107

STANDARD SPLICE JOINT FOR CHANNELS FOR AXIAL LOAD Sr. No.

Item Description

A

B

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

ISMC-75 ISMC-100 ISMC-125 ISMC-150 ISMC-175 ISMC-200 ISMC-225 ISMC-250 ISMC-300 ISMC-400

60 80 110 135 160 180 205 230 280 376

75 115 155 165 215 265 310 280 375 475

Web Cover Plate C D 25 25 50 50 50 50 60 160 60 70

250 330 410 430 530 630 720 660 850 1050

T 8 8 8 8 8 10 10 10 10 12

Weld S1 5 5 5 6 6 6 6 8 8 10

Flange Cover Plate Bxa L Weld S2 45 x 8 50 x 10 65 x 10 75 x 12 80 x 12 80 x 14 90 x 14 100 x 14 110 x 14 120 x 16

250 290 300 400 450 500 550 600 675 800

5 5 5 6 6 6 6 6 6 6

108

STANDARD SPLICE JOINT FOR CHANNELS USED AS BEAMS Sr. No.

Mark

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

ISMC-75 ISMC-100 ISMC-125 ISMC-150 ISMC-175 ISMC-200 ISMC-225 ISMC-250 ISMC-300 ISMC-400

Flange Cover Plate Section Length b1 x s1 L1 45 x 8 240 50 x 8 270 70 x 10 340 75 x 12 370 80 x 12 450 80 x 12 500 90 x 12 500 100 x 12 520 110 x 12 560 120 x 16 700

Web Cover Plate (Both Face) Section Length Weld b2 x s2 L2 h 120 x 6 60 5 120 x 6 80 5 120 x 6 110 5 120 x 8 135 6 120 x 8 160 6 120 x 8 180 6 140 x 8 210 6 140 x 8 235 6 140 x 10 280 8 150 x 10 370 8

109

Sr. No.

Mark

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

ISA 50 x 6 ISA 65 x 6 ISA 65 x 8 ISA 75 x 6 ISA 75 x 8 ISA 75 X 10 ISA 80 x 6 ISA 80 x 8 ISA 80 x 10 ISA 90 x 6 ISA 90 x 8 ISA 90 x 10 ISA 90 x 12 ISA 100 x 8 ISA 100 x 10 ISA 100 x 12 ISA 110 x 8 ISA 110 x 10 ISA 130 x 10 ISA 130 x 12 ISA 150 x 10 ISA 150 x 12 ISA 150 x 16 ISA 150 x 18 ISA 200 x 16 ISA 200 x 20

Length I 230 270 290 300 320 400 320 330 400 340 370 400 420 400 400 430 430 550 470 540 570 610 670 720 860 90

Splice Plate Width B 55 70 70 75 75 75 80 80 80 90 90 90 90 100 100 100 110 110 130 130 150 150 150 150 200 200

Thickness T 6 6 8 8 10 12 8 10 12 8 10 12 14 10 12 14 10 12 12 14 12 14 18 20 18 22

Minimum Weld Size h 5 5 6 5 6 6 5 6 6 5 6 6 6 6 8 8 6 6 8 8 8 8 10 10 12 12

110

Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

Mark ISA 50 x 6 ISA 65 x 6 ISA 65 x 8 ISA 75 x 6 ISA 75 x 8 ISA 75 X 10 ISA 80 x 6 ISA 80 x 8 ISA 80 x 10 ISA 90 x 6 ISA 90 x 8 ISA 90 x 10 ISA 90 x 12 ISA 100 x 8 ISA 100 x 10 ISA 100 x 12 ISA 110 x 8 ISA 110 x 10 ISA 130 x 10 ISA 130 x 12 ISA 150 x 10 ISA 150 x 12 ISA 150 x 16 ISA 150 x 18 ISA 200 x 16 ISA 200 x 20

Length of Splice Angle „L‟ 320 380 500 440 500 500 450 500 500 500 500 500 560 600 600 650 600 650 690 750 790 790 810 850 1200 1300

Packing Plate Length „L1‟ Width „B‟ 150 55 150 70 150 70 200 80 200 80 200 80 250 90 250 90 250 90 250 100 250 100 250 100 250 100 250 100 250 110 250 110 300 120 300 120 300 140 300 140 400 160 400 160 400 160 400 160 500 210 500 210

Min. Size of Weld 6 6 6 6 6 8 6 6 8 6 8 10 10 6 8 10 8 8 10 10 10 12 14 16 14 16

111

TABLE FOR CONVERSION OF ROLLED SECTION TO PLATE SECTION

A T

T

t B

t

Type Butt Weld

B

A

Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Rolled Sect. ISMB 150 ISMB 200 ISMB 250 ISMB 300 ISMB 400 ISMB 450 ISMB 500 ISMB 600 ISMC 200 ISMC 250 ISMC 300

A 80 100 125 140 140 150 180 210 75 80 90

B 150 200 250 300 400 450 500 600 200 250 300

Equivalent Section T t 8 6 12 6 16 8 16 8 16 10 20 10 20 12 25 12 12 8 16 8 16 8

Wt./ Meter (Kg.) 16.35 27.12 45.09 51.99 64.05 79.91 100.60 134.23 25.18 33.78 39.43

Rolled Sect. Wt./ Meter (Kg.) 15.0 25.90 38.10 45.10 62.20 73.10 87.70 123.50 22.30 30.60 36.30

Note : 1. 2. 3.

All welds are 6mm fillet continuous unless noted. All dimensions are in mm. z All steel shall confirm to IS 2062 Grade B

112

SIZES AND PROPERTIES OF STEEL TUBES FOR STUCTURAL PURPOSES IS : 1161-1979 Nominal Out side Class Thick Weight Area of cross Moment Modulus Bore Dia: ness Section of Inertia of Section of Gyration

Mm 15

mm 21.3

20

Radius

L M H

Mm 2.00 2.65 3.25

Kg/m 0.962 1.22 1.45

Cm2 1.21 1.55 1.84

Cm4 0.57 0.69 0.77

CM3 0.54 0.65 0.73

CM 0.69 0.67 0.65

26.9

L M H

2.35 2.65 3.25

1.42 1.58 1.90

1.81 2.02 2.41

1.38 1.50 1.72

1.02 1.12 1.28

0.87 0.86 0.84

25

33.7

L M H

2.65 3.25 4.05

2.04 2.46 2.99

2.58 3.11 3.77

3.14 3.65 4.22

1.86 2.16 2.51

1.10 1.08 1.06

32

42.4

L M H

2.65 3.25 4.05

2.61 3.15 3.86

3.31 4.00 4.88

6.57 7.71 9.07

3.10 3.64 4.28

1.41 1.39 1.36

40

48.3

L M H

2.9 3.25 4.05

3.27 3.61 4.43

4.14 4.60 5.63

10.70 11.73 13.90

4.43 4.86 5.75

1.61 1.60 1.57

50

60.3

L1 L2 M H

2.9 3.25 3.65 4.5

4.14 4.57 5.10 6.17

5.23 5.82 6.50 7.89

21.59 23.77 26.17 30.90

7.16 7.89 8.68 10.2

2.03 2.02 2.01 1.98

65

76.1

L M H

3.25 3.65 4.5

5.84 6.53 7.92

7.44 8.31 10.1

49.44 54.65 65.12

13.0 14.4 17.1

2.58 2.56 2.54

80

88.9

L M H

3.25 4.05 4.85

6.86 8.48 10.1

8.74 10.8 12.8

80.31 97.38 113.46

18.1 21.9 25.5

3.03 3.00 2.98

90

101.6

L M H

3.65 4.05 4.85

8.82 9.75 11.6

11.2 12.4 14.7

134.9 147.9 172.9

26.6 29.1 34.0

3.47 3.45 3.42

100

114.3

L M H

3.65 4.5 5.4

9.97 12.1 14.5

12.7 15.5 18.5

194.4 234.3 274.5

34.0 41.0 48.0

3.91 3.89 3.85

113

Nominal Bore

Out side Class Thick Dia: ness

Mm

mm

110

127.0

125

Weight

Area of cross Moment Modulus Section of Inertia of Section

Radius of Gyration

Mm

Kg/m

Cm2

Cm4

CM3

CM

L M H

4.5 4.85 5.4

13.6 14.6 16.2

17.3 18.6 20.6

325.3 347.7 382.0

51.2 54.8 60.2

4.33 4.32 4.30

139.7

L M H

4.5 4.85 5.4

14.9 16.2 17.9

19.1 20.5 22.8

437.2 467.6 514.5

62.6 66.9 73.7

4.78 4.77 4.75

135

152.4

L M H

4.5 4.85 5.4

16.4 17.7 19.5

20.9 22.5 24.9

572.2 612.5 674.5

75.1 80.4 88.5

5.23 5.22 5.20

150

165.1

L M H

4.5 4.85 5.4

17.8 19.2 21.2

22.7 24.4 27.1

732.6 784.5 864.7

88.7 95.0 105.0

5.68 5.67 5.65

150

168.3

L M H1 H2

4.5 4.85 5.4 6.3

18.1 19.6 21.7 25.3

23.2 24.9 27.6 32.1

777.2 832.4 917.7 1053

92.4 98.9 109 125

5.79 5.78 5.76 5.73

175

193.7

L M H

4.85 5.4 5.9

22.6 25.0 27.3

28.7 31.9 34.8

1284 1417 1536

133 146 159

6.68 6.66 6.64

200

219.1

225 250 300 350

244.5 273.0 323.9 355.6

L M H H -

4.85 5.6 5.9 5.9 5.9 6.3 8.0

25.7 29.4 31.0 34.2 38.8 49.5 68.3

32.6 37.6 39.5 44.2 49.5 63.4 86.5

1874 2142 2247 3149 4412 7992 13111

171 195 205 258 323 493 737

7.58 7.55 7.54 8.44 9.45 11.2 12.3

Steel tubes are designated by their nominal bore and are classified as “Light” –L Medium” –M and Heavy”- H depending on the wall thickness. Permissible Stress in Axial Compression for Steel Tubes of Grade YSt 210 IS : 116-1979 I/r

kg/sq.cm

I/r

kg/sq.cm

I/r

kg/sq.cm

I/r

kq/sq.cm

0 10 20 30 40 50 60

1250 1217 1175 1131 1088 1046 1002

70 80 90 100 110 120 130

970 929 876 814 745 674 603

140 150 160 170 180 190 200

540 490 432 381 339 304 271

210 220 230 240 250 300 350

243 219 198 180 162 106 71

114

L/r is slenderness ratio: L being the effective length and r the radius of gyration RECOMMENDS SIZES OF ISMB FOR MONORAIL/ LIFTING BEAMS Maximum Span 2 Mtr. 3 Mtr. 4 Mtr. 5 Mtr. 6 Mtr.

2T Beam Section ISMB-150 ISMB-200 ISMB-200 ISMB-200 ISMB-250

Maximum Load to Be Lifted 3T 4T 5T Beam Section Beam Section Beam Section ISMB-200 ISMB-200 ISMB-200 ISMB-200 ISMB-250 ISMB-250 ISMB-250 ISMB-250 ISMB-250 ISMB-250 ISMB-250 ISMB-300 ISMB-250 ISMB-300 ISMB-300

10T Beam Section ISMB-250 ISMB-300 ISMB-350 ISMB-400 ISMB-450

PROPERTIES OF INDIAN RAILS

Type of Rail

25R 30R 35R 40R 45R 50R 55R 60A 65A 70A 75A 80A 85A 90A 95A 100A 105A 110A CR 50 CR 60 CR 70 CR 80 CR 100 CR 120 CR 140 120 Lbs

Area of Whole Section 2 m 15.8 19.03 22.19 25.29 28.51 31.67 34.9 38.9 41.22 44.38 47.74 50.71 53.74 57.35 60.13 63.8 66.45 69.35 38.02 50.99 67.30 81.13 113.32 150.44 195.53

Weight Kg/Mt.

Moment of Inertia 2 cm

12.41 14.94 17.42 19.85 22.38 24.87 27.4 30.54 32.36 34.84 37.48 39.8 42.18 45.02 47.2 50.09 52.16 54.44 29.85 40.03 52.83 63.69 88.91 118.11 153.49 60

115.7 162.32 220.17 290.04 374.58 476.13 570.61 687.56 797.85 911.89 1049.02 1209.06 1374.7 1557.42 1741.79 1950.72 2143.84 2343.2 357.54 654.6 1081.99 1547.4 2864.73 4923.79 7427.23

Distance top neutral axis cm 3.76 4.06 4.34 4.7 5.03 5.36 5.61 5.92 6.07 6.25 6.47 6.78 6.98 7.24 7.41 7.79 8.07 8.40 4.68 5.67 6.07 6.57 7.40 8.57 9.16

ZXX 3 cm

A mm.

B mm.

C mm.

30.77 39.94 50.73 61.72 74.47 88.83 101.71 116.14 131.44 145.90 162.16 178.32 196.95 215.11 235.06 250.41 265.65 278.95 76.40 115.45 178.12 235.52 387.12 574.54 811.02

73.0 76.0 86.0 92.0 97.0 105.0 109.0 115.0 119.0 124.0 129.0 133.0 138.1 143.0 149.0 152.4 156.0 158.7 90.0 105.0 120.0 130.0 150.0 170.0 190.0 172.0

38.1 41.28 44.45 47.63 50.01 52.39 54.77 57.15 50.74 60.32 61.91 63.5 65.09 66.67 69.85 69.85 69.85 69.85 65.0 65.5 76.5 87.0 108.0 129.0 150.0 74.3

69.8 76.0 83.0 89.0 95.0 99.0 104.0 110.0 113.0 117.0 123.0 127.0 122.2 137.0 140.0 133.3 136.0 139.7 90.0 105.0 120.0 130.0 150.0 170.0 190.0 150.0

115

ASTM A36 ANCHOR BOLTS

Dia mm

L mm

A mm

DIMENSIONAL PROPERTIES AND ALLOWABLE LOADS B C D Threads Pitch Tensile Shear Area 2 2 mm mm mm Per Inch mm Area At in As in

16

400

100

65

335

75

12.70

2.00

0.2292

0.2989

Allowable Tension Shear KIPS KIPS 4.58 2.9

20

500

120

65

435

75

10.16

2.50

0.3599

0.4691

7.20

4.6

24

650

150

65

585

75

8.467

3.00

0.520

0.6775

10.4

6.2

Notes : 1. 2. 3. 4.

Bolt material specification conforms to American standard ASTM A 36 (Yield Strength = 36 K.S.I. Minimum). Allowable load values may be increased by 33% for wind loading. Minimum specified compressive strength of concrete = 300. Minimum projection of bolt beyond nut should be equal to thickness of nut. AS TM A325 HIGH STRENGTH BOLTS DIMENSIONAL PROPERTIES

116

Bolt

E

F

G

H

R

Body Dia

Width Across Flats

Height

Radius Fillet

Max.

Min.

Max.

Min.

Width Across Corners Approx

Max.

Min.

Max.

Min.

Max.

M12

12.70

11.80

22.00

21.20

25.40

8.80

7.20

0.80

1.60

M16

16.70

15.80

27.00

26.20

31.20

10.80

9.20

1.20

M20

20.80

19.60

32.00

31.00

37.00

13.90

12.10

M22

22.80

21.60

36.00

35.00

41.60

14.90

M24

24.80

23.60

41.00

40.00

47.30

15.90

Nut

F

Min

Thread Length Min.

Transition Thread Length Approx.

30.00

25.00

3.50

2.00

35.00

30.00

4.00

1.20

2.00

41.00

35.00

5.00

13.10

1.20

2.00

46.00

40.00

5.00

14.10

1.60

2.40

51.00

45.00

6.00

Washer

of

Max.

Min

M12

22.00

21.20

25.40

12.35

11.65

M12

13.70

13.00

26.00

25.20

3.60

2.80

M16

27.00

26.20

31.20

16.35

15.65

M16

17.70

17.00

32.00

31.00

5.00

4.00

M20

32.00

31.00

37.00

20.40

19.60

M20

21.80

21.00

40.00

39.00

5.00

4.00

M22

36.00

35.00

41.60

22.40

21.60

M22

23.80

23.00

44.00

43.00

6.70

5.30

M24

41.00

40.00

47.30

24.40

23.60

M24

25.80

25.00

48.00

47.00

6.70

5.30

Across

Max

Y

G Width Across Corners Approx

Width Flats

H Thickness Hex. Nuts

Lr

A Inside Dia.

B Out Side Dia.

C Thickness

Max

Min

Max

Min

Max

Min.

WEIGHTS & STANDARD SIZES OF STEEL (BLACK) SHEETS Thickness Weight 17 1.40 11.00

BG mm Kg/ sq. m

16 1.60 12.55

15 1.80 14.15

28 0.40 3.15

26 0.50 3.90

24 0.63 4.95

22 0.80 6.30

21 0.90 7.05

20 1.00 7.85

19 1.12 8.80

18 1.25 9.80

14 2.00 15.70

13 2.24 17.60

12 2.50 19.60

11 2.80 22.00

10 3.15 24.75

9 3.55 27.85

8 4.00 31.40

7 4.50 35.30

117

BG is Birmingham Gauge No. which is nearest to the standard thickness in mm. Steel sheets in odd BG gauges, viz., 9, 11, 13, 15, 17, 19, 21 are not generally manufactured except by special arrangement (for bulk supply). Standard Lengths are : 1800, 2000, 2200,2500, 2800, 3000, 3200, 3600, 4000, 4500mm. Standard widths are : 600, 750, 900, 1000, 1100, 1200, 1250mm. Theoretical weights in kg/sq. m have been calculated on the basis that steel weights 7.85 kg/s. m per mm thickness, or 7.85 grams/ cu. Cm rounded off to the nearest 0.05kg. Sheets of thickness above 4mm are classified as plates. COMPARISON OF WEIGHTS OF SHEETS OF DIFFERENT METALS In Kg/Sq. Meter For 16 BG gauge (1.588mm) thickness – approximate Cast Iron 11.47

Wrought Iron 12.20

Steel 12.55

Brass 13.37

Copper 13.08

Lead 18.10

Zinc 11.42

Aluminum 4.26

WEIGHTS & STANDARD SIZES OF STEEL STRIPS In kilograms per meter length per 10mm width Thickness Weight

11 2.80 0.220

BG mm Kg/ /m/10mm

10 3.15 0.248

16 1.6 0.126

9 3.55 0.279

15 1.80 0.141

8 4.00 0.314

7 4.50 0.353

6 5.00 0.392

14 2.00 0.157

13 2.24 0.176

13 2.50 0.196

4 6.00 0.471

2 8.00 0.628

0 10.00 0.785

BG is the No. nearest to the standard thickness in mm. Standard widths are : 100, 125, 160, 200, 250, 320, 400, 500, 650, 800, 950, 1050, 1150, 1250, 1300, 1450, 1550mm. Weight of mild steel flats and plates Width in mm x thickness in mm ------------------------------------------- = kg per meter 127 WEIGHTS & STANDARD SIZES OF STEEL PLATES Thickness Weight

mm Kg/ sq. m

18 141.30

20 157.00

5 39.25

22 172.70

6 47.10

25 196.25

8 62.80

10 78.50

28 219.80

12 94.20

14 109.90

16 125.60

32 251.20

36 282.60

40 314.10

Sheets of thickness above 4mm are classified as plates. Standard widths are : 900, 1000, 1100, 1200, 1250, 1400, 1500, 1600, 1800, 2000, 2200, 2500mm. Standard lengths are : 2000, 2200, 2500, 2800, 3200, 3600, 4000, 4500, 5000, 5600, 6300, 7100, 8000, 9000, 10000, 11000, 12500mm.

118

WEIGHTS OF PLAIN & CORRUGATED GALVANIZED STEEL SHEETS Thickness

Mm BG

1.60 16

1.25 18

1.00 20

0.80 22

0.63 24

0.50 26

0.40 28

Weight

Kg/sq. m

13.31

Class I (750g of zinc coating per sq. m) 10.56 8.60 7.03 5.70

4.65

3.90

Weight

Kg/sq. m

13.16

Class II (600g of zinc coating per sq. m) 10.41 8.45 6.88 5.55

4.50

3.75

Weight

Kg/sq. m

13.01

Class III (450g of zinc coating per sq. m) 10.26 8.30 6.73 5.40

4.35

3.60

Weight

Kg/sq. m

12.94

Class IV (375g of zinc coating per sq. m) 10.19 8.22 6.66 5.32

4.27

3.52

Zinc (spelter) coating is on both sides. Corrugated sheets. In the corrugated galvanized iron sheets (CGI), the depth of corrugation is 18mm and the pitch 75mm. Number of corrugations are 8 or 10 per sheet. 10 corrugations is most common. 75cm wide flat sheets are given 8 corrugations and 90cm wide sheets 10 corrugations, which reduce the width of the sheets to 60cm and 80cm (sometimes 11 corrugations are given to 99cm wide sheet reducing the width to 88.5cm).

Weights of corrugated sheets are worked out based on weights of plain galvanized sheets taking into account width of sheets before corrugation. s

119

CONNECTIONS IN STEEL STRUCTURES. Connections are junctions and meeting points of two or more parts of either a single structure or two are more different structures, for example gusset plates of a truss, auxiliary girder or a bracing system on which two or more members are welded to transfer their forces. Other example is connection or meeting places of column and truss, column and eve girders, column and auxiliary girders, beam with column and main beam with secondary beam etc. In all connections gusset plates or end plates play an important part since through the gusset and end plates only compressive or tensile forces or moments are transferred to adjoining structures which in turn transfer forces and moments to the main or intermediate columns and ultimately transfer them to the foundation. It is important that the fabrication/erections drawings show this connection correctly and properly, so that there is no confusion or doubt during fabrication and erection of structures. Before preceding it is to clarify that bolts are generally provided for erection purpose and contact surfaces are to be welded after alignment of structures. Even after welding of contact surfaces it is always advisable to leave these tightened erection bolts in position, erection bolts can be removed once site welding is completed since it is the weld which is designed to transfer the stresses, but if removed the blank holes must be plugged by welding so that air, moisture and other acidic or alkalines fumes which will be always present during operation of plant / factory do no enter the micro gaps and harm inside surfaces of meeting member by rusting, pitting and corroding. More over in a factory or plant hundreds and thousands of erection bolts are used and their removal and plugging by welding is it self a cumbersome process requiring lot of man power and time along with welding electrodes etc, which is quite costly affair. In bolted connections with H.T. bolts or with high strength friction grip bolts, no welding is to be done. These bolts themselves serve the purpose of erection bolts and are kept slightly loose to help alignment. After structures are aligned, then these bolts are tightened to the required designed torque by torque wrenches or by use of turn method and checked by torque wrench at random places. in bolted connections matching of holes of different members is very important. If machined bolts are used the holes in shop are drilled to one diameter less than the required size and after assembling of structures on ground at erection site these are reamed to required size and than proper size of machined bolts are provided with nuts. After this nuts are tightened. In all type of bolted connections it is required that one washer below bolt head and one washer above nut of desired specification is provided. Thus for every bolt two washers will always be required.

Welded connections in shop drgs. 1)

End connection of trusses, roof girders, auxiliary girders, and eaves girders etc. with columns flange or web:

120

Y X

Y

X

FIGURE - 2

FIGURE - 1

VIEW Y- Y VIEW X- X

Gap g 10mm. to 15mm. should be kept at all places. A typical connection is shown in figure 1 while showing above detail following points should be kept in mind. 1)

2)

3)

4)

Minimum projection of gusset beyond angle should be weld size + 2 to 3 mm. example if 8 mm. fillet welds is to do provided (item 4 with item 1) then projection should be 8+2 = 10mm. Gap between end plate and chord angle or diagonal angle or between tips of 2 angles should be minimum 20 mm. This is required in order to avoid crossing of two weld lines. In absence of 20mm. gap and providing less gap, weld lines will over lap or cross each other and their by harming the metallurgy of common zone. In all important heavy members minimum weld length required on both sides of member should always be mentioned. The length of weld should be designed length + 2t where “t” is the thickness of weld. Since gusset dimension depend upon length of weld these may differ from dimensions shown in drawing, for this a general note should be mentioned to the fact that all gusset dimension should be verified from actual full scale lay out and can be increased/decreased to accommodate required weld lengths which should be the guiding factor.

Gusset connection with top chord angles when cleat for purlins is to be provided.

121

Here the point to note is to avoid shy welds on main gussets of structures, due to the fact that shy welds can not contribute resistance to designed forces. Even when purlin cleat is to be welded at such places a notch equal to leg length of cleat + 10 mm. long and 10 mm. in depth should be provided and before welding of cleat with top chord sealing ran of weld should be provided in notch and only after this cleat should be welded with top chord. For bottom chord also all main gussets should project 10 to 15 mm. beyond main bottom chord angles. If bracing gussets are to be provided on bottom chord these should be in 2 half and no bottom chord bracing angle gusset should be in single width. This is shown below.

122

When top chord of a truss is a single angle or channel. Gusset plate can be provided as sown above gap g at all places should be kept min. 20mm. in order to avoid interference or crossing of weld lines other points regarding weld length and showing welds as explained in figure 3 should also be followed. Bottom chord truss connection with column. 20 mm. WELD

GUSSET PLATE. WELDED WITH COL.IN SHOP

Column FIGURE-6

In truss connection if last diagonal is inclined from top chord to bottom chord than the type of connection at top and bottom shall be reversed.

123

Note:The gap „g‟ is important and the connecting members should in no case be extended so as to touch column flange or web as the case may be.

Beam connections. Connection involved are 1) Beam connection with column flange or with Column web 2) Beam connection with web of another beam which is similar to beam connection with column web. Only connection with flange and with column web is given below.

Column flange to beam. X P Y

Y

X

SECTION X- X DETAIL- P

SECTION Y- Y FIGURE - 7 Gap g 10mm. to 15mm. should be kept at all places. In above type of connection if simply supported type connection is provided then in that case moment plate may not be there.

124

Col web/ beam web to beam.

X

X

SEC TIO N X- X FIGU RE- 8

Moment plate connection welding details are same as shown in previous figure.

SOME IMPORTAN POINTS. In nut shell following points should be kept in mind. 1)

In welded connation weld lines should never cross. In case this situation can not be avoided always provide no weld zone 25 mm. on each side of along longer weld line. Example horizontal and vertical welded joints in web of deep crane girder.

The figure show position of no weld zones. 1)

In truss joints between 2 weld lines keep a clear distance of 20 mm.

2)

Gusset be kept dependable instead gusset examples are shown

plates should not shy since proper welding is not possible, should always be prout below.

125

Exception: - stitch plates between double angles can be kept shy since they do not transfer forces. 1)

All gussets and stitch plates between double angles in a structures should be of same thickness.

2)

Zones where welding (either site or shop) is not required should be high lighted with a note on drawing.

3)

Machined edges where ever required should be indicated on drawing.

4)

All gaps required shall be clearly mentioned

5)

If you are showing typical indication then show it at one place very clearly and do not repeat at random to avoid confusion.

6)

Parts/ items where specific features are required should be shown separately and other connecting items should not be shown.

10)

Triangle of inclination should invariantly be shown on all inclined members.

11)

Parts which are to be welded in shop or site should be clearly inclined on drawing.

12)

Dimensions on drawing should be clear so as to facilitate easy working and making lay out in the shop, leaving no scope for measuring distance on drawing.

13)

For showing proper dimensions and welding details, joint should be separately drawn on bigger scale.

14)

Welds which are to be tested ultrasonically are radiographically should be clearly marked on drawing.

15)

In bolted connections holes should cross match with holes in corresponding structures.

16) must

17)

Star angles be drawing below.

Important levels be mentioned on all structures after ascertaining their correctness. where ever used must represented and shown in properly example is given

126

Please remember that in star angles the angle shown in firm lines (angle A) in elevation will be shown always above angle shown where thickness of angle is shown in dotted lines (angle B) it is absolved that often mistake is made and sections are shown wrong. In drawings made on computer for section and details COPY PASTE method is always used to save time. Before use of any section or detail made in some other drawing which is already available in the computer memory, always ensure that it matches exactly with your requirement.

127

PART-3 ERECTION OF STEEL STRUCTURES

128

ERECTION OF STEEL STRUCTURES Erection of steel structures is an important and unavoidable phase of every industrial building during its construction period. The structural erection work starts when civil work of construction of foundations / pedestals has been completed at least to the extent that erection of steel structures can be started, sequentially. The civil construction of foundation / pedestal should proceed minimum 10 to 15 days in advance. This is required in order to allow concrete to gain minimum 75% of strength before it is subjected to dead load of structures which will be erected on it. When we talk of structural erection it is compulsory that steel structures are available at site in sequential manner in adequate quantity and continuity of supply of steel structures is maintained in required sequence. The sequential supply is insisted due to the reason that if large quantities of structures are supplied in non sequential manner, it will be lying for a long time at site and occupies a large part of restricted working space. Not only this but long time storage may result in damage due to over loading remanding and rusting due to whether conditions. Presence of Erection Engineer The time when presence of erection engineer is required should be at least two to three months in advance from the date from which actual erection work is to start. This is required in order to give time to understand site requirement, get acquainted with organizational setup and to be involved right from inviting tender for erection work. If it is decided to get the work of erection done through an erection contractor, erection engineer has lot of home work to do before actual erection starts in understanding the drawings, standards and specifications according to which erection and finishing work has to proceed. Study of Drawings This is most important point of structural erection. Study the drawings carefully not once but many times. This will enable the erection engineer to visualize the complete form of shed/ building. While studying drawing following salient features must be given special attention. Study and note type of anchor bolts in foundation from civil drawings and also note the position of civil foundations and the physical conditions of the bolts. By this I mean the vertically of foundation bolts, accuracy in dimension of foundation bolts, condition of protection of threads, match dimensions of holes in structural drawings and actual dimension of the bolts provided at site. The Sequence of Erection Structural erection is always done in a pre-decided sequence. This is necessary to provide proper and regular fronts for mechanical and electrical installation and above all for safety. Following points are always followed universally. 1. 2. 3.

Erect those columns which are braced with each other. Immediately after erection of columns erect bracings. Nuts on foundations bolts should be tightened to the maximum extent humanly possible with standard spanners after erection of columns.

129

4.

5. 6.

7.

8.

9.

10. 11.

12. 13. 14. 15.

16. 17.

Before erection of columns either steel pack plates (tack welded with each other) or control blocks are provided on pedestal well in advance in such a way that top of packing level matches with bottom level of column base plates. Such packings are provided min. 4 to 6 or more nos. and fixed on top surface of pedestal / column footing. Over the top of these packing pads. Column is erected. This provides correct level of column base plates and also provides gap for grouting below base plate of column after alignment. After column & bracing erection, gantry girder is erected and bolts are provided as per drawing on columns in a row. Now align column and level it, if required shims can be inserted on the steel pack plate or separate pack plates can be provided, these additional or extra plates should be tack welded with base plate of columns so that there is no movement of pack plates. After alignment and leveling of columns now align crane girders and tighten holding down bolts of gantry girders with columns cap plate and also tighten bracing bolts with torque wrench. Similarly tighten foundation bolts of column to the required extent. After alignment and leveling of all 4 columns in the block erect roof legs of columns if these are not erected with main column. The connection of roof leg with main columns should be tightened manually and after alignment of roof leg these bolts should be tightened to the required level with the help of torque wrenches. If there are (generally should be) bracings between roof legs these should also be erected immediately after erection of roof legs. Now trusses / rafters erection should be done and simultaneously erect minimum 50% of purlin on either side with bolts of purlin to truss in semi tightened condition. After alignment of trusses/ rafters all connection bolts should be tightened to the full extent as per drawing. Erection of bottom chord bracings of trusses / rafters should be taken up immediately after alignment of trusses / rafters and connection bolts should be tightened. Now this block is the reference and erection of further columns and trusses can proceed on either side or on both sides of this block, always connect the new erection with this block by erecting connecting structures. All filling in items like purlins, side runners, auxiliary girders, eaves girders etc. should be erected. Stairs and ladders if any should be erected on priority in order to provide safe access to various levels. Rail erection on top flange of crane girders can start immediately after auxiliary, girders, surge girders and platform chequered plates are erected. Remember to grout column bases before crane is erected on the rail by crane supplier at least 7 to 10 days in advance. Ensure that during these 7 to 10 days. Grouting below column base plate is cured properly and regularly. Crane rail alignment and level should be checked and recorded and is signed by crane supplier/ erector and the erection engineer. Sheeting work can also be started after all purlins are erected and connection bolts of truss to column are tightened. Finally provide finishing paint on structures as per specifications mentioned in contract agreement/ drawings.

In erection following rules should be strictly adhered to a. b.

Never allow further loading of structures unless connections or finally finished i.e. in case of bolted connections all bolts are tightened to the full extent in case of welded connections all fillet and butt welds are completed, inspected and tested by ultrasonic or gamma ray as per specifications if prescribed. If erection bolts are shown leave them in tightened position even after joints are site welded. If these bolts are removed open holes will be left through which moisture and chemical vapors will enter and harm steel plates by rusting or pitting.

In sequential erection stress has been given on executing braced bay first. But at site there may be a situation when due to civil foundations readiness, availability of structures and approaches etc. sequential erection from braced bay can not be started but even then erection must be started 130

due to demand end date of completion, in such situation erection engineers has to decide from his own experience and technical knowledge. He can start erection from any suitable location and provide temporary bracings between 2 cols on each row. The temporary bracings may be in the form of angles or channels, and proceed with erection as per procedure mentioned above. These temporary bracings should be removed when erection is completed or after permanent bracings as per drawings are provided properly. Position of Approaches Many times it happens that though the foundations are ready but there is no approach. This may be due to excavations done but not filled up, storing of civil or structural materials in between or on going civil work of piling, excavation, binding of reinforcement or shuttering work, passing of temporary water discharge pipe lines and electrical cables etc. clear approach to the exact foundation where erection is to start must be made. Since structures and cranes are be taken near the foundations. Weights of Structures Erection engineer must be aware of a. b.

Total wt. of structures to be erected. Weight of heaviest single piece of structure which is to be erected. Generally columns are heaviest part. This is required in order to asses the weight-lifting capacity of equipments to be arranged and deployed. Ensure that all equipments tools and plant should be of 10% to 25% higher capacity then the weight of structural members to be handled.

Time Management Erection engineer has to be a good time manager. Since the period with in which work is to be completed is defined, all materials, equipments and labour has to be deployed in such a way that maximum output is taken and there is no idling of these factors. At the same time erection engineer has to watch and keep close control on these factors and the progress of work. Requirement of additional resources at the right time and also their withdrawal at right time should be well thought and planned in advance. In fact work progress is nothing but fight against time and hence the importance of time management. A Guide for Structural Erection Now let us take a case where 500MT of structures are to be erected in a period of 4 months. This gives an average of monthly target of 125MT. an average out put of 1 man / 1 Ton / month can be safely assumed. The structures involve columns, crane girders, roof trusses , eave girders auxiliary and surge girders, column & roof truss bracings, purlins, side runners and miscellaneous structures like platforms, mono rails, ladders and stairs etc. for completion all above average out put 125 persons are required out of these about 20 persons will be needed for sheeting work. When actually sheeting starts leaving a side these 100 persons will be needed for erection, aligning, finishing, transportation of structures internally and for other services. These 100 persons must be divided in to 7 or 8 groups and each group must consists of following combination.

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Category Sarong or Group Leader Riggers (Skilled Labours for Erection ) Fitter Gas Cutter with Cutting Set Welder with Welding Machines Helpers for Welder & Gas Cutter Total

Nos. Required 1 7 1 1 1 2 13 Nos.

For making 7 groups nos. required will be 13 x 7 = 91 balance 9 should be of rigger category and form one group who should supplement the groups and should be engaged is unloading of structures received from shop, loading and transporting structures with in the plant and supply structures at the point of erection as per sequence of erection. These people should be under control of a supervisor who should deploy them as per instruction of erection engineer. Supplying structures should be 1 or 2 days in advance in order to ensure that erection groups and crane etc. do not idle for want of structures at any time. Out of the 7 groups 5 groups may be engaged for main erection of structures and 2 groups on finishing work like alignment, tightening of bolts etc. and on erection of minor items and various filling in items. Main 5 groups proceed with erection work and 2 groups follow them completing the erection of filling in items and finishing. Now this is a broad distribution and as per requirement no. of groups can be increased or decreased for finishing and alignment or in erection of filling in items. When 3 or 4 spans of building is finished sheeting work can start by engaging sheeters as described in the beginning. Instruments to be Kept at Site Following instruments should always be available in the site office 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

Steel Tape - 50 Meters Steel Tape - 3 Meters Set of filler gauges from 0.1 to 1 mm Steel Scales 1 Meter Long Steel Scales ½ Meter Long Steel Right Angles 500mm Long Steel Right Angles 300mm Long Level Tubes Verneer Calipers Binaculars (long range)

2 Nos. 6 Nos. 1 with each supervisor and fitter 2 Nos. 2 Nos. 3 Nos. 2 Nos. 3 Nos. 4 Nos. 2 Nos. 1 Nos. for observation work at height by erection engineer Brass or steel plumb bobs (1 Kg. 4 Nos. Wt.) Brass or Steel Plumb bobs (500 4 Nos. Gram Wt.) 5 Kg Hammers 4 Nos. 2 Kg Hammers 4 Nos. 1 Kg. Hammers 4 Nos. Small steel Hammers (200 grams) 2 Nos. (These are required for checking with 300mm Wooden Handle tightness of bolts) Calibrated Torque Wrenches 2 Nos. for tightening bolts from 25 to 56mm dis. Calibrated Torque Wrenches 3 Nos. for tightening bolts from 12 to 25mm dis. Pino wires 2 Bundles each having 100 meters length Spring Balance 4 Nos. having capacity to provide a tension from 0 to 10 Kg.

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21. 22.

Steel spikes Turn buckles

23. 24.

Theodolite Dumply Level

12 Nos. or more 10 to 12 Nos. of various capacities to provide tensely from 100 Kg to 5 Tons. 2 Nos. with Staff. 2 Nos. with Staff.

Spring balance is required to give 5 to 7 Kg tension to tape joint taking correct measurement, usually 5 to 7 Kg tension is given. Note : Other then above there may be many other measuring appliances and devices which are required for specific requirement. Keeping walky-talky is of great help since a person working at height can easily be in contact with the supervisor on ground for passing and receiving instructions and there is no need of shouting. Erection Equipments & Plants An erection engineer must be familiar with the plants and tools used during erection, about their functions and capacities. Main equipments are given below 1.

Cranes Cranes of various capacities and boom lengths are available, maximum capacity of any crane is at the minimum boom length in up-right position. As the boom length increases capacity of same crane is reduced also the inclination of boom affects the capacity such that as the angle with horizontal plane decreases the crane capacity reduces, it is vice versa with vertical plane i.e. lesser the angle with vertical plane the crane capacity increases. Now the selection of proper crane depends upon weight of heaviest piece to be erected and height at which it is to be erected. Cranes of 5 Ton to 200 Ton capacities are available in both crawler type or pneumatic tyre mounted type. For structural purpose 20 to 50 ton capacity cranes are suitable. Again the highest structures height decides the boom length. The crane hook should always be 2 to 3 meter higher then the highest point of the structures. This is required to accommodate hook length and sling length.

2.

Derricks : Function of derrick is same as that of cranes with the difference that in cranes every movement is mechanically controlled where as in case of derricks every movement is manually controlled. Erection by derricks is cumbersome and time taking and more risky then erection by crane. Now a days derricks are used rarely. How ever in remote areas where availability of crane is not there or crane can not be taken due to obstructions derricks are the only means for erection of structure.

3.

Winches Winches are available manual type as well as mechanically operated and are of various capacities. Winches are always used along with derricks or with single pulley or with pulley blocks for lifting or shifting of structures.

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4.

Pull Lift Machine The common name used is hook-chuk this is attached with column footing or other heavy immovable construction and is used for horizontal or vertical movement of structures manually. This comes in various capacities. It is operated manually by operating a leaver attached to the machine. This machine is very good when movement required is in few centimeters.

5.

Slings Slings are made from high tensile wire ropes. These are readily available in different diameter and lengths in the market. These are silected according to the specific need, considering the weight of structures to be lifted and top clearance from hook of lifting device which may be a derrick or a pulley block. Slings which are tested and are in good condition should only be used and should be inspected regularly. Any wire strands if found broken or cut the sling should not be used. Sling is always coated with cardium compound to keep strands flexible for proper functioning, this compound gets dried due to use and atmospheric conditions there by making strands hard and susceptible to breaking when load is lifted and hence proper care should be taken to regularly maintain the slings by applying cardium compound at least once in a month to all slings and wire ropes which are in use. Some times it has been observed that some riggers make the sligns at site from wire rope, such slings should not be used to lift heavy loads since they are untested and may become cause of accident at any time.

6.

Precautions in use of wire rope slings The slings should not be kept with heavy loads hanging for long time then the required, by this it is meant that if a column, truss, or crane girder is lifted then it should be placed at its place immediately, in case of trusses / rafters end connecting bolts should be provided and (at least 50% of bolts are tightened by spanner, so that sling is free from load however slings can remain in position till all connections bolts are provided. After this only slings can be released from structure)

7.

Wire Ropes, Jute / Nylon Ropes These are also available in different diameters and in bundles of 20,50 or 100 meters depending on diameters in the market. Only tested quality of reputed brand should be procured and used. Steel wire ropes are used mainly as Guy Ropes to hold the structures safely till they are secured and are self supporting. Jute or nylon rope are used to control the movement of lifted structures. In the desired direction or to prevent free rotation of structures like trusses, crane girders, eve girders etc. this is done by toying 2 long ropes at the end of structures and the other end is held by riggers on the ground as the crane lifts the structure. Use of nylon ropes is now a days more common since they are strong and for same diameters have capacity to sustain more loads, further nylon ropes are unaffected due to whether effect and are light in weight than jute ropes. Nylon and jute rope also used to lift light structures like hand railing, bracing members etc. manually with the help of a pulley hang from bottom of roof girder, roof truss, columns etc.

8.

Guy Ropes These are steel hi-tension wire ropes and are used to provided temporary support to cols, trusses etc. and are always used with spikes and turn buckles. Precaution for use are same as wire rope slings, guy ropes can be temporary or permanent.

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9.

Turn Buckles Turn buckles are also available for different capacities in the market and are often used to give tension to guy ropes.

10.

Steel Spikes These are steel angles (90x90x10 & 100x100x10 etc.) of 1 to 2 meter length with one end cut angular. These are driven inside ground by hammering on flat end in an angular direction as per requirement and then guy ropes are attached with turn buckle. With the help of turn buckle tension is given to guy rope and the steel spike provides resistance to pulling of guy rope and thus guy rope is always in tension and in tight condition.

11.

Some Basic Precautions 1.

2.

3.

Ensure the equipment, tools and plants which are deployed for erection are of higher capacity at least 10 to 25% than the weight of the piece they are supposed to lift. While lifting heavy and long items after putting the slings in crane hook just lift the piece a few centimeters say 30 to 50 cm above ground and ensure that position of sling is correct and balanced, if not bring down the structure on the ground and adjust the slinging points, again lift it few centimeters above ground and make the piece of structure steady, before this ensure that required labourers with their tools are in position and are ready to receive the structure. Now crane operator should be given signal to lift structure in a study manner without any jerks. Except Sarang (group leader) nobody else should give signal for lifting or lowering of structures.

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Some other important points Tightening of Nut Bolts Welded Connections Where connecting members are to be site welded after erection and alignment, the erection bolts can be tightened by standard spanners manually till there is no gap between connecting members. This is required for proper welding. Welding a joint with gap in between the surfaces of connecting members is not advisable. In case it becomes totally un-avoidable due to limitations of tightening then in that situation the gap should be packed with shims which are not allowed to project out side of joining surfaces. After packing the weld size has to be increate by amount of gap. For example 6mm filled weld is to be provided and gap can not be reduced less than 2mm minimum then after packing the gap 8mm (6+2) fillet weld should be provided. Bolt whether permanent or for erection are always tightened from centre to out side end of connection and not in reverse order. Then only gaps can be reduced. Similarly it is a good practice to leave erection bolts in their position even after joint is welded. This avoids filling of holes with welding which is a very difficult and time consuming job. In addition these bolts and nuts when left in tightened condition provide safety in case of poor and bad weld. Permanent bolted connections In all prefabricated buildings all erection connections are invariably bolted. The bolts are high tension bolts in clearance holes and take load when they are tightened to a pre-designed torque by calibrated torque wrenches after alignment and leveling. The tightening again should be in the sequence from centre to wards ends as explained earlier. There are 2 options a.

Tighten all the bolts with torque wrench in this process you require lot of torque wrenches. It is not possible to tighten each and every nut to tighten with torque wrench due the position of bolts in odd places where there is no space to fix torque wrench. In these cases an alternate method as below is also used commonly.

b.

Turn of nut Method in this method bolts are tightened by standard spanner by an average healthy man to the maximum extent. After this nut corner is marked on nut by marker. Similarly opposite end position (3rd corner of hexagonal nut for ½ turn and 4th corner of nut for 3/4 in clock wise direction is marked on connecting plate). Now this manually tightened nut is further tightened by using pipe lever attached to spanner up to the point that mark on nut matches with mark on plate.

When all bolts in a joint are tightened with above method, 10% of nuts are tested with standard torque wrench and if 10% nuts are found OK. It is considered that all bolts are OK. In case of failure further tightening is done with torque wrench of all loose nuts. The above procedure is fast and dependable and is acceptable.

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HIGH STRENGTH FRICTION GRIP BOLTS This is one of the advanced method of connection and is used for heavy industrial buildings and bridges for roads and railways in many countries. But it require very high standard of quality control in providing & matching of holes in connecting members. The fabrication and erection also needs to be of high quality. The majority of members come to erection site in knock down condition. After arrival matching surfaces are sand blasted so that these matching surfaces do not have any rust or paint over there and original shining steel surface is visible so that the assumed friction is developed, after this in all matching holes HSFG bolts, nuts and washers are provided and tightened manually with standard spanner. Further tightening is done either following the turn method or with the help of torque wrench so that required torque between nut and bolt is developed this will ensure that friction assumed is present between the matching surfaces. When all these bolts are checked then the structures are finally painted. After this structures are erected to there final position. Tightening bolts and nuts with cols, roof legs etc. have to be done at height, only experienced engineers and supervisors should handle the job. WORKS OF ERECTION ENGINEER There is slight difference in the work when an erection engineer has to work on behalf of client and when he has to work on behalf of contractor. Comparatively work of an engineer working of on behalf of contractor is of more responsibility, some of the points are highlighted below: A.

Contract and contract conditions

An erection engineer must be well aware of contract in order to enable him to discharge his duties satisfactorily. If you are working on behalf of contractor than primary responsibility of erecting, finishing and handing over of finished structure as per requirement of contract in the stipulated time lies with you. It should be ensured that 1. 2. 3.

4. 5.

6. 7. 8.

9.

Proper tools, plants and machinery and consumables are available not only in sufficient quantity but with spares. Work is divided properly amongs various groups who will work in particular area with responsibilities fixed and explained. Proper safety items are available at all the time for each persons like safety belts, helmets, goggles etc. Safety rules must be made compulsory for every body. A first –aid centre with a trained person who should be present till erection work is in progress. An erection engineer must know the monthly or weekly progress targets and organize his works accordingly. He should know total tonnage to be erected and the specific time of completion. Continuous assessment of work progress should be there and corrective measures are taken timely. He should be thorough with drawings and specifications and conditions of contract. Work which is done should be got approved from clients engineer after satisfying him self. He must know what structures are required and place his requirement to the client at least 7 to 10 days in advance to ensure continuity of progress. Where erector is also fabricator he should coordinate with fabrication shop in order to get the structure in time. Any extra work/ rectification done which is not supposed to be done by erector should be jointly recorded with clients engineer for claims at later date.

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10.

He should be a member of site progress review meetings and accept such targets which are possible to achieve with available means with him in case higher targets are required to be set for backlog of progress or for handing over fronts to other agencies he must frankly ask for additional resources or facilities from the client. To summaries it can be stated that „achieving set targets in a time bound phased manner is an essential part of working for any project and it should be very clear that starting of activities by further agencies depends upon timely completion of activities by previous agency. The delay can be compressed to some extent but abnormal failure will spark delay / failure by other subsequent agencies and ultimately delay in project completion. In this delays beyond human control are exceptions. When an erection engineer is working on behalf of client and is in charge of supervising erection by contractor the nature of duties differ slightly. The main work is to guide the erection work in proper direction so that required target of progress is achieved for this following points are to be born in mind. 1. 2. 3. 4.

5. 6.

You should have full set of drawings and study them thoroughly the total tonnage of erection and final date of completion. Type of joints between column and roof leg, joints of trusses / rafters to roof leg, rafter to rafter / truss to roof girders and other joints. How crane girders are connected with column cap either by knife edge bearing / or full bearing of bottom flange at end resting of crane leg cap. In case of bolted connections ensure that all bolts are tightened to the full designed torque. This can be done either by tightening each nut by torque wrench or by turn method; the method should be discussed and mutually agreed prior to starting of work in order to avoid un-necessary controversies at latter stage. All tightened bolts are checked by client representative and proper record maintained which should be signed from client and contractor side. Further loading of structure should be done only after completion of erection and completion of all important members are erected and finished. In case of welded connection further loading should be allowed only after joints are fully welded. The reason for insistence of completion of joint is explained below.

In case of welded connection if load is transferred before welding it will be taken by erection bolts along with dead load of structures which the erection bolts are not supposed to take. Now even if welding is done the weld will take the load only when erection bolts shear. The transfer of load will be with a sudden jerk and the weld may fail. Similarly when it is a bolted connection with H.T. Bolt and if load is allowed prior to completion of tightening it will be transferred to these un-tightened bolts in gap and bolts will be under stress. Further tightening of these stressed bolt will be very difficult. It is found at site that in-spite of knowing this fact technical personnel at site ignore this fact for progress and this should be avoided. Contract Study the contract and note what the responsibilities of client are? In general at erection site free water and power supplying at one point, providing easy access to the erection agency, first aid etc. are the client‟s responsibility. For any worker, technician, or supervisor almost in each contract the client is principle employer and ultimate legal responsibility is that of client. So it is to be ensured that the contractor has proper work license, insurance of workers & staff and machines against all types of accidents and causalities and follows the law of that nation.

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Payments to Contractor Any bill submitted by the contractor has to be scrutinized by the clients erection engineer. Delay in checking of bill will delay payments to contractor which will lead to further delays in labour and consumable payments which has indirect but definite negative effect on progress. Hence if you are working on behalf of client side, you should also try for prompt payments. Drawing Problems Clients engineer must ensure that erection drawings are given in time to the contractor in advance. The erection engineer him self should thoroughly study drawings and solve any site problem by giving right solutions if required with consultation of designer / consultants in time so that work is not held up. Please remember that if there is abnormal delay due to drawings, supply of structures, or in giving solution to the problems arising due to no fault of erection contractor, the erection contractor is entitled to claim idle charges for labour and machinery and extension of completion time and hence an erection engineer has to take care properly. Progress & Reporting Erection engineer is an integral part of site progress meeting or any meeting called to discussed various problems related with structural erection due to the very fact that he is the only authority who has first hand knowledge of erection site. Erection engineer must submit progress report in proforma giving target fixed for the week or month, progress achieved, short fall, and up to date progress and up to date short fall, total tonnage to be erected. In this progress report he should also mention reason for short fall. The short fall may be due to lack of main power, lack of availability of fabricated structures, lack of availability of machineries, or consumables etc. this report should be submitted to the higher authorities at least 2 days in advance so that proper thought can be given and corrective measures are discussed during site meetings by all, site erection engineer should also have his own say in the progress meeting for improving the rate of progress. Only piece of advice is that “verify your self and then only report. “ Reporting on here-say may put you in awkward position in the meetings. Permissible Deviations in Erection of Structures It is a well known fact that it is not possible to bring erected structure to ± 0.00 limit. Hence need of permissible deviation is there many of countries have their own standards and it is always better to follow that standard. In case of absence of such standard. Standard mentioned in contract or on drawing should be followed or any international code like British code or American code or Indian code etc. should be followed. One important point should be noted that design, fabrications and Erection should follow the same code. It should never happen that design is for example British code, fabrication American code and erection by that country‟s code. Erection engineer must have the specified codes. It should be remembered that if fabrication of structure is done correctly, erection is smooth and fast. Any mistakes and deviations more than the permissible limits if available becomes biggest head ache of erector who has to erect, align, finish and hand over the structures for commissioning. So ensure that fabricated structures are thoroughly inspected in shop before dispatch to site. Permissible deviation in erection for columns, trusses / rafters crane gantry girders etc. are enclosed. These are given as a general guide lines and mostly taken from British code 5950.

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Safety This is the most important factor which is often neglected at every site. Negligence of safety results in accidents, which causes loss of human life, loss and damage to machinery & materials and delay in completion. No one man can specifically be a cause of accident but even then in 99% cases of accidents it is the human error due to which accident happen. Out all losses, loss of human life is the verst. Since life once lost can not be brought back, it is not the suffering of one man who meets with a fetal accident but life long suffering for the dependents. Following should be the aims of erection engineer. 1. 2. 3.

Cultivate habit of use of safety appliance in every body from worker to the chief of project. Aim should be to make the project 100% accident force. Safety before starting of work, safety during the work and safety after the work till every one reaches home and is greeted with smiling faces of his family. In my experience of 45 years of working in steel industry after analysis I come to the conclusion that accidents always happen due to following causes. a. b. c. d. e. f.

a.

Falling or Collapse of Earth in Excavations. Fire Hazards. Sudden Gush of Rain & Wind. Electric Shock Falling from height and Falling Materials. Failure of Lifting Equipments.

Falling or Collapse of Earth in Excavations. In case of accidents due to collapse of earth proper slopes if given to cutting edges and stacking of excavated material minimum 3 meters away from final excavated edge can save accident to a large extent due to collapse of earth.

b.

Fire Hazards : Flammable materials should not be stacked in open no bare electric wire should pass over or from near the stacked materials. The materials should be covered with fire resistant cover and the area should be cordoned and un authorized entry should be allowed even during day or night. Adequate no. of fire extinguishers should be available near such materials to ensure immediate availability when needed. Other fire extinguishers materials like sand and water should be kept near the flammable materials. Oil, grease, petrol, diesel and other lubricant material, coal tar drums DA & LPG Cylinders etc. should have separate store and should not be stored with other materials. Any gas cutting or welding should be avoided over these flammable materials or in immediate vicinity. The area where flammable materials are kept should be strictly „Smoking Prohibited Area‟. The area should be fitted with fire alarm and security personnel should always guard during day & night.

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c.

Sudden gush of rain & wind. This is a natural phenomenon and is present every where. Though this can not be prevented but nature always gives sufficient warning in change of atmosphere before storm and if any such signal is seen erection work should come to a halt. Now a days with advance technique weather reports and warnings are available on television and radio. Watch should be kept on these warnings and proper steps to stop work should be taken well in advance.

d.

Electric Shocks This is another major cause of accidents at site if shock is mild it may not be fetal and first immediate first-aid and subsequent medical help saves life in most cases but high voltage shocks may be fetal. Even if the shock is mild and person is working at height he will fall down and may result in a fetal accident. These shocks are result of total human negligence. It is often observed that joints in cables and wires are not properly covered or the joints are left bare open. When these improperly covered joints come in contact directly with a person or contact with steel structures or wet ground the current is spread to quite a long distance and workers get electrocuted and injured. At most care is to be taken in joining of welding cables and temporary wires which are often drawn for running of welding machines, drill machines or area lightening. Properly trained electricians only should be employed and work under electrical supervisor. At site it is observed that even laboures, fitters, welders connect the machines to switch board or to the distribution box. Electrical personnel should carry rubber hand gloves and should be allowed to work only with insulated instrument. In charged lines no body even electricians should be allowed to work until power in switched off.

e.

Falling from height and falling materials. Majority cause of accident at erection site is attributed to this where either person or persons working at height fall down or some materials like nut bolts or tools slips from the hands of the person working at height and falls down on the person passing from the area. Also loose structural members, like purlins, cleat angle, sheets, sag rods etc. which are left on top of trusses fall due to heavy winds or vibrations caused due to various reasons and when these materials hit any one standing or passing through the area may result in fetal injury. To prevent such type of accidents following precautions may be taken. 1. 2. 3. 4. 5. 6.

Leave no materials like purlins, sheets; nut bolts small tools etc in loose conditions on top after days work is over even if these are required next day. All workers / engineers and supervisors should put safety helmets before they enter work area. All workers should be given hand gloves to protect hands. All workers should wear safety belts without fail before climbing and should hook securely before starting work at heights. Welders and gas cutter must wear safety goggles and special hand gloves and aprons for protection of face specially eyes hands and body. Every body should wear tight dresses before starting of any type of work in project area. Similarly leather shoes must be put on by every one irrespective of his position.

These measures will lessen chances of accident to a large extent.

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f.

Accidents due to failure of machines and lifting tools and devices Some times accident do happen at site due to above reasons. For preventing following steps may be taken. 1.

2.

3. 4.

Never lift any structures with lifting device having capacity just equal to the weight to be lifted. In fact lifting capacity of device should be 20 to 25% more. If equipment is new, in case of old equipment capacity of lifting device should be 40 to 50% higher same should be the case with lifting tackles like slings & wire ropes. Maintain timely all equipments, lifting tools and plants and keep them in working conditions. The equipment should be tested periodically as recommended by the manufacturers. Never keep load in hanging position for long time as longer hanging results in heating of wire rope strands and in heated condition the capacity is reduced. Miss use of equipment should always be avoided like pulling of column on ground by using crane or lifting and transferring machines in the bucket of excavator etc or pulling by road rollers or other earth moving machines.

Always it must be remembered that machines are never cause of accident but it is their misuse, non proper maintenance etc. by human beings is the main cause of their failure. What ever is mentioned for safety is nothing new and known to all engineers but still why accidents happen practically at every site is a matter to be given serious thought by every one. First Aid Centre Every erection site should have a full fledged first aid centre fully equipped with required medicines and facilities a trained person must be present in this centre as long as work is going on. Further it may not be possible to have an ambulance at every erection site but it can be ensured that at least one fast moving 4 wheeler vehicle is always available at site to meet any emergency. The first aid centre must be easily approachable at all the time. Communication facilities like telephone, mobiles should be available at site. So that one can call the hospital for ambulance during emergency and also can contact the concern authority of the project.

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ERECTION TOLERANCES FOR STRUCTURES

Erection tolerances shall be as given below : Fixing Bolts Fixing bolts include holding down bolts for columns and various other type of bolts used to support other members. Bolts Fixed in Position All foundation bolts shall be fixed in position before concreting of foundation / pedestal with the help of rigid templates supplied by the fabricator or prepared and approved by site erection engineer. The holes in templates shall exactly match with the holes in base plate of columns. In case of laced column having 2 legs both templates shall be connected with each other rigidly for alignment of bolts for verticality, centre line matching and matching of axis and top level of bolt. Bolts will be held rigidly by welding with reinforcement so that the bolts remain vertical during concreting. The templates shall be removed only after 72 hours by method which will neither disturb position of bolt nor damage threads of bolt during removal. If required for progress reason more sets of identical templates can be prepared. The template material shall be 5 to 10mm M.S. Steel plates. Pre Set Foundation Bolt or Bolt Group 1.

Deviation in level of concrete

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2.

3.

Bolt Position.

Permissible Deviation of Anchor Bolts (Plan) a.

Located with in contour of structural footing ± 5mm.

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b.

Located out side contour of structural footing ± 10mm.

4.

Permissible deviation in anchor bolt elevation +20 to 0mm.

5.

Permissible deviation of Anchor Bolt Thread Length + 30 to 0mm. Position at base of fist column erected.

Over Plan Dimensions i. ii.

L is less than 30 meters Δ = ± 20mm L is more than 30 meters Δ = ± 20mm, +0.25mm (L-30) L=30 mtrs.

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Column Plumb Deviation at gantry level relative to base

Single Story Column Plumb (without gantry)

(Deviation at toe of roof leg)

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Multistory Building

Alignment of adjacent columns Deviation relative to the next column in line

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Floor Beam Level Deviation from specified level at support

Floor beams level at each end of beams (inclined)

Floor beams level of adjacent beams with in a distance less than 5 Meters Deviation from relative levels measured at centre lien of top flange

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Beams Alignment

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Crane Gantry Gauge of Rails

Joint in Gantry Crane Rails

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Shift in Gantry Girder Web Centre from Col. Leg.

Shifting of Crane Web Centre Line & Rail Centre Line.

Permissible Gaps in Joints

1.

Bearing Surfaces The bearing contact between end plate of crane girder with column crane leg cap plate or any other joint where one end of plate is shown bearing on other surface shall be as below. 80% of bearing area shall have full contact and at scattered places 0.2mm i.e. at such places 0.3mm filter should not go.

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At Other Places in Bolted Connection Gap between end plate of beam and column flanges, between end plate of rafter / truss with column flange, rafter / roof truss to rafter / roof truss at the contre. The permissible gap shall be as shown

In both cases permissible Gap Δ = B/100 but not more than 3mm. In Welded Connections In Connections where bolts are provided only for erection purpose, after alignment of structures all bolts should be tightened to maximum extent and than gap shall be measured in all joints mentioned above at no place gap between the plates shall be more than 0 to 2mm. If gap can not be reduced to 0 the site weld size shall be increased by 2mm i.e. if drawing specifies 6mm fillet actual weld size shall be 8mm.

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The erection bolts should be tightened and should be left in position and in no case should be removed after site welding. Shims in Gaps of Joints Gaps which remain over the specified tolerances when the members are in their final alignment may be shimmed by using float shims. The shims used shall be in short length in variety of thicknesses in steps not exceeding the permitted deviation shall be used. Not more than three layers of shims should be used at any point. One or two layers of shims are preferable. Shims must be held in position after packing by means of tack weds or full weld or partial butt weld extending over the shims see figure.

In bolted compression splices bolted finger shims as shown in (b) can be used. In some cases shims can be driven in, but for driving shim the thickness of shims should be 2mm and above. Permissible gaps in sheds or buildings where fumes are detrimental to mild steel are present, like buildings for acid storage, acid regeneration where acidic fumes or fume of any other chemical are always present at no joint gap should be more than 0 to 0.2mm. If gaps are more at any place it should be filled by providing shims and preferably sealing the joint by giving a thin run of weld say 4 to 5mm all-round the joint. Lock Nuts or Check Nuts In the following joints lock nut or check nut shall always be provided over the main nut in order to prevent loosening of main nut due to vibrations generated in structures by moving cranes and due to vibrations generated by running of other heavy machines and equipments on the floor of other shed. 1. Over column foundation bolts main nut. 2. Over holding down bolt nuts of gantry girder with cap plate of column leg. Notes: - lock nuts all always provided full tightening of main nuts and tightened to full extent. Lock nut thickness is less than main nuts.

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PART- 4 INDUSTRIAL – PROJECTS Site – Selection

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In INDIA and other developing countries there is a boom in establishing various kinds of projects in the field of cement, energy, petroleum, pharmaceutical products mining and other inter related industries. The reason being, one the population has increased and secondly the standard of living is going up and up. Since there can not be a stoppage to any of the above two reasons, establishing of industrial projects and factories has entered in a non stopping phase. For starting establishing and running any industry, huge natural resources are being consumed and every day alternate sources are being searched through researches going on in every nation. The progress of information technology and computer science has added wings to all above activities during last 30 year. For industrial plants various sizes of plots are required depending upon the nature of industry varying from few 100 square meters to thousands of square kilometers and even more. Such plots may be available in industrial areas being developed by various governments if land required is comparatively small for small factories. In these industrial areas facilities like road power water etc. Are provided by government at the door steps where as for large industrial units like, cement plants rolling mills steel plants etc. very big size of land is necessary which can be acquired by purchase from one or more owners with permission of appropriate authorities, or taken on lease from government if the area is Inhabited and uncultivated and belongs to state/central government, in such cases the owner has to arrange himself for water power and other facilities at his own. Before considering the various suggested sites one has to be clear regarding. a) b) c) d)

Type of plant to be set up. Approximate minimum area required to setup the plant. This can be known by own experience or by visiting existing other similar plants. What are the proposed expansion plans by the client in future? Whether the proposed plant is to be set up in stages.

SITE SILECTION This is the most important factor for the successful and economical operation of the Industry; any mistake in selection may ruin the plant. While selecting, all pressures especially political local and financial in the form of commission are brought on the selector appointed by owner to give favorable report for a particular site. But economical success of plant should be the only motive before the selector. After considering all pros and cons of two or three locations, the best site should be recommended with reasons to the owner. Following points if kept in mind will be helpful. COMMUNICATION AVAILABILITY. This includes the distance from a city or town which is well connected by air, railway, port or river for traveling and establishing office, rest house etc. for personnel, goods and construction materials, equipments etc. These facilities if readily available will help in reducing time in construction of projects and there by timely commissioning of the plant.

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TOPOGRAPHY OF LAND This is an important aspect the location of any industrial plant should be on an average on flat ground so that minimum excavation and filling is required, more over excavation and filling should evenly balance. If excavation is less lot of filling material is to be boroughs from out side and if excavation is too big than excavated material has to be disposed off. Hilly areas or deep valley areas should be avoided as far as possible in such areas lot of time is consumed initially in leveling the area. NEAR NESS TO RIVER/CANAL BANK OR SEA The plot location should not be too close to river/canal bank or sea shore. One thought of school favors nearness due to the fact that material transportation is cheaper and easier through the water ways provided by river/canal or sea. But this has a distinct disadvantage from safety point of view of civil foundation and footing. In first instance lot of costly embankment protection for river/canal or see shore is to be done secondly the ground water table always fluctuates as per the level of sea or river/canal. The fluctuation of ground water table has a detrimental effect on foundations and raft footing which is subjected to fluctuating up lift pressure constantly. Even during construction when 12 to 15 meter deep excavation is involved the excavation edges are to be protected heavily by using sheet piling which is again a costly and time consuming process. Thirdly water rushes so much that it is very difficult to control ground water inflow inside excavation. Even after sheet piling inside vacuum dewatering system is to be installed and run continuously during construction of raft and wall to a height above ground water table. Even. After completion there is every likely hood of sinking of foundation. Cases are known where even foundations on piles have sunk during operation of plant, there by disturbing the alignment of crane girders and column footings. It is very difficult to predict the final effect. In my opinion no plant with heavy foundations should be located with in (especially where the ground is sandy or sandy silt.) 1 to1.5 kilometers from sea shore or river/canal banks, the extra cost involved in transportation of materials is worth ,considering the safety and long life of plant as a whole, how ever people may think differently. LOCATION OF SITE BELOW FOOT OF A HILL OR HILLOCK. Any plant site just below foot of the hill should be avoided for the following obvious reasons. 1)

2)

Water / snow from hill top and slope in rainy/winter will flow directly in the plot. If unavoidable adequate precaution to prevent entering of snow and water in plant will have to be taken, which will involve additional cost. If the hill or hillock is susceptible to land slide this fact should be ascertained from past history. If land slide occurs unexpectedly the debris and boulders may fall in the plot with great force and damage the plant and result in loss of human life and plant machinery. Due to above reasons it is better to avoid location of site just below foot of hill of very high rise ground. If it is totally unavoidable the site should be ½ to 1 km away from the foot of hill with proper precaution and measures to prevent detrimental affects of above elements should be taken.

AVAILABILITY OF WATER, POWER & NATURAL GAS These are most essential elements required. Since no industry can run without water and power. 156

Water: - It should be investigated if any perennial river or canal is passing near by, from where water can be made available. Huge quantity of water is required during processing and for boilers, cooling and for consumption by staff, workers and for their colonies (when located in the plant premises). Ground water table and possibility to draw ground water should also be explored and mentioned in the site selection report, how ever treatment plant for water will always be required to remove impurities to bring the quality to acceptable standards. POWER & NATURAL GAS a)

Power is another important factor and uninterrupted supply to industry has to be ensured. Possibility to get power from government through near by substation should be mentioned, alternately own power generation through D.G. sets/ gas generators (if gas is available from government lines) or from steam turbines should also be given a thought. Availability of gas facilitates not only in running gas generators but is also necessary for heating of furnaces during processing of products. Gas is always cheaper in comparison to other resources. Even if power is available from government supply, stand by power generation units will be required in case of sudden failure or break downs to run minimum units of plant.

AVAILABILITY OF CONSTRUCTION MATERIALS. If construction materials like, cement steel reinforcement bricks or concrete blocks etc. are available in local market or in nearby vicinity, this helps in faster and economical construction of projects. NEAR NESS OF ROW MATERIALS By this it is meant that if the plant is consuming raw minerals like iron ore, limestone bauxite coal etc. then it is always economical if these minerals are available very near to the plant vicinity, if not all at least major basic mineral should be available in which case other required minerals are to be brought from out side, This in turn increases a large space requirement for storage of these items at plant site as buffer stock for 10,15 days or 1 to 3 months depending upon the time taken to receive these minerals forms out side. When the plant‫י‬s feeding material is a finished product form other plant which is to be imported or purchased from out side than sufficient large storage space is required at plant site so that plant can run for 3 to 6 months on this stock. Example for such plants is cold rolling mill which uses hot rolled coils as feeding material, CGL, continuous galvanizing) mill which uses cold rolled coils as feeding materials, steel melting shop (SMS) which uses cast iron ingots or hot rolling mill for which feeding material is thick slabs from Slabing mill. Some times SMS,HRM, CRM & CGL are all there in the same premises along with color coating mill, corrugation mill etc. What is meant is that type of raw material depends upon the type of mill or complex of mills which are to be established. ANCILLIERY INDUSTRY Availability of ancillary industry in near by locality is another important factor which should also be given due consideration during construction as well as during operation of plant, if ancillary facilities like machine shops electrical repair facilities for motors. Airconditionnsers, compressors, pumps, fabrication of steel and aluminum doors and windows if available help a lot. In absence, these facilities are to be established at plant site by the owner him self.

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AVAILABILITY OF CONSTRUCTION EQUIPMENTS & P.O.L. During construction, equipments like excavator, Bulldozer, Dumpers, compressors, cranes, piling rigs batching plants etc. are often required, if these equipments are available in near by town or city, construction is faster and economical. In case these are to be brought from distant places then construction is delayed since lot of time is consumed in transportation of these equipments to site more over idle charges are also to be borne. It may be mentioned that these equipments are required periodically and not continuously. To run these machines and vehicles petrol, diesel, and various types of lubricants are required. Nearby availability ensures uninterrupted functioning of these equipments otherwise adequate storage of P.O.L items has to be maintained at site. If batching plant is not available storage for cement, sand and aggregate has to be provided along with concrete mixers at site. The storage of there materials occupy lot of space and other movements are restricted. AVAILABILITY OF SKILLED AND UNSKILLED MENPOWER During construction phase of any project lot of skilled and unskilled persons like, masons, welders, fitters gas cutters, electricians, riggers, Sarangs and unskilled laborers are needed, it is helpful if these categories are available locally, in absence of availability, these categories are to be brought from outside and arrangement for their lodging and boarding is to be provided during construction period. Simultaneously it should be surveyed if good civil contractors, fabricators and erectors, and electrical contractors are available in near by towns or cities, unskilled manpower is required even during running of plants. DISPOSAL OF EFFLUETNT After process is complete effluent and waste in the form of liquid, Sámi - liquid or solid is an essential part of every industry. These are to be disposed off according to the rules and norms set by government, in such a manner that no harm is caused to the habitants including animals and to the natural water bodies. In site investigation this aspect should also be looked into and site selection report should also mention about this, however it is a fact that effluent treatment plant is a essential part of every industry to prevent pollution of adjoining land and atmosphere. Possibility as to how sewage will be disposed should also be investigated on an over all basis. RAIN WATER HARVESTING What ever type of industries are to be established, long shades are to be constructed and during rainy season huge amount of water is available through rain water drain from the roof. Since rainwater is purer than ground water or river water, this quantity of rain water should not be allowed to flow through natural drains to rivers etc, instead this should be collected in separate underground tanks and can be supplied after treatment as drinking water to the residents of plant, office and factory. If very large quantity of water is available this water can also be used in plant. Alternately this water should be left in special pits to be absorbed in ground of plant premises so that the ground water table is maintained and can be used in dry season through bore wells.

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A)

OTHER FACILITIES BY GOVERNMENT

By this it is meant that if facilities of tax benefits are available from government side if plant is located in specific area for a project, if so it should be clearly mentioned in the site selection report. While investigating and selecting site all the above points need to be considered for various proposed sites and all advantages and disadvantages of each suggested site should be mentioned. It may be kept in mind that no site is absolutely ideal, every site will have some or other odd points along with favorable points. The site which has maximum favorable conditions should be recommended. However the final decision is to be taken by the client after discussing the report.

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PART- 5 INDUSTRIAL – PROJECTS PROPOSED LAY OUT PLAN OF A PLANT.

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PROPOSED LAY OUT PLAN OF A PLANT.

In case of a new project after site is decided and land is procured this is the next step for which discussions are held amongst various groups and experts to arrive at the most feasible, lay out plan of the plant including ancillaries and service units and ideas are put on drawings, Two or three alternate plans are prepared and are discussed in depth. Following points are to be kept in mind. 1) Orientation of the plant and auxiliaries. 2) Leaving sufficient space for future expansion if planned. 3) Leaving ample storage space for feeding materials and finished goods. 4) Easy excess for entry of materials and dispatch of finished goods. 5) Convenient location of office and administrative blocks. 6) Sufficient parking space for heavy & light vehicles. 7) Ample space for roads inside plant between different units and for pipe lines, Electrical cables, Rain water drains, Effluent disposal pipes, Water supply and sewerage pipe lines. 8) Provision for worshiping (TANPLE OR MOSC). This is particularly for INDIA AND MUSLIM CONTRES. In case the plot is already acquired and is part of expansion. Some of the above points may not be required but keeping proper distance between old and new plant has to be considered similarly inter connectivity for easy excess of raw materials/ finished goods etc. Should be kept in mind and provided for while proposing lay out of new plant. GENERAL PROCEDURE AND ORGANISATION. The whole process of preparing a lay out for a particular type of plant is a complex process which requires opinion of Electrical, Mechanical, Civil, and various experts of other disciplines. In nut shell for this various groups should be formed and each group should be headed by a senior and experienced person in every discipline. The group‟s leader shall take opinion and suggestions from his subordinates and arrive at a conclusion as to what should be the requirement of that discipline for that particular plant in general. That is to say what are the units and approximate area/sizes are required for that particular plant sequentially. If possible small sketch/drawing should be made. Above all there should be a project coordinator to whom all these group leaders should give their requirement. The project coordinator shall have one or two senior draftsman who has experience in preparing plant lay out under him. The project coordinator should try to accommodate requirements of all group leaders and prepare a rough lay out taking in to consideration the size & area of land available. The shape of plant may be L shape E shape [ shape etc. Or the coordinator may decide the whole plant in 2 or 3 stories. The rough lay out plan should only show blocks with names and size. When this rough plan is available all group leaders and experts should discuss with open mind and arrive at 2 or 3 alternatives which should be presented to the client and after discussion with client and his experts, equipment suppliers a final lay out with modification/alteration should be decided. Once the lay out is agreed by all parties the accepted lay out should be free zed and further work of design for civil and structures should be started. This too is only in short, how things should proceed. POINTS TO BE NOTED. When ever a plant is proposed, study the project in depth and note down details as below. 1) What are the raw material/materials for the plant? 2) What is the finished product? 161

3) Capacity of the plant. 4) Flow diagram of the project. 5) How many intermediate stages through which the raw material is processed before it is converted into the finished product. For example, Teaming, welding, galvanizing, cutting, corrugation etc. This is for HRM, CRM, CGL, etc. For different type of finished materials the stages will be different. 6) What clear dimensions are required by the supplier for each process and over all length and width? 7) What are the auxiliary units, like ECRS, Stores, Boilers, Chimneys, Compressors, Generator rooms, Repairing work shop, Roll grinders, Store for electrical, mechanical and other spare parts including chemicals? 8) Storage capacity for raw materials depending upon the stock to be maintained for 10, 15, 30 or 90 days depending upon the availability. This store has to be provided in front i.e. starting point of plant or in the near by area. 9) Storage area for finished product, this again will depend for periods ranging from 15 to 90 days etc. as per speed of flow of sales, of finished goods. 10) Weighing facilities for raw materials as well as finished goods. 11) Units for P.O.L storage, acid storage, acid regeneration plant, E.T.P. are to be located with clearance all around as per norms and hence provision for the area required should be there in the plant premises. 12) In every plant gases like nitrogen, Hydrogen, oxygen etc. are required. The area should have provision for storage and production plants of these gases at independent locations. 13) All the above points should be noted and while making lay out space should be provided for. ACTUAL LAY OUT PROPOSAL. An example is taken for consideration. Suppose a plant is to be established for finished product `B` The raw material is A which has to under go 12 operations before it is converted to finished product `B` naturally each operation will have its machines and will be with foundation and will require minimum specified space required by the supplier. To run these 12 machines it will have electric power, hydraulic oil, compressed air, water, steam, gas (some of them or all) connections depending upon functions at each process and will be supplied to the machine by pipe lines and cables. There has to be return pipe for water, hydraulic oil etc. for which provision is to be made in the form of different trenches or pipes. Since there are 12 such machines all these facilities may be required at all places or some facilities may not be required but power in any form electrical, hydraulic, compressed air etc will be required. Again for these there will be auxiliary units for power, hydraulic oil, steam, compressed air, repairing work shop storage for spares laboratory, electric control room, chimney etc. There has to be storage for raw material A at the entrance and storage for finished good B at the exit. The ideal lay out will be that material A enters. And finished good B comes out at the exit point. Auxiliaries are located on left or right of the main plant with minimum distance form the various process units in order to have minimums length of various pipes and cables. One such lay out is shown in sketch

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Ideal size of plot is rarely available and all requirements are to be accommodated in the available plot size or area. With this constraint, past experience and study of existing similar plants is required in order to accommodate all requirements. ARRANGEMENT OF UNITS. The arrangement of units depends upon many factors. Some of these are as under. PLOT FALLS SHORT IN LENGTH. In such case the various activities are divided in parts and each part contains group of activities and these groups are arranged in parallel .In such case product is to be transferred form one part to another and for transferring, trolley tracks, conveyors or cranes will be necessary. PLOT FALLS SHORT IN REQUIRED WIDTH. When situation as above activities can be shifted in stories i.e. one above the other. Even some activities can be taken under ground and one or two stories above ground. If this is adopted arrangement for vertical shifting of processed material from one floor to another floor are to be provided with the help of cranes or lifts etc. In nut shell the project coordinator and all group leaders have to put their ingenuity technical skill and experience in coming to a conclusion which is most economical and advantageous, taking in to consideration future expansion of the existing plant and proposed new plants in the same premises taking care for all types of constraints. In deciding the lay out ground topography also plays on important role for arrangement of various activities in the lay out of plant. It should be clear in mind that even after finalization of lay out during construction slight adjustments are always necessary due to demand of machine suppliers. This is due to the fact that while quoting, the suppliers provide initial dimension as per what ever drawings are available with them but when detail design of machine is done there is variation. It is a known fact that serious workings on designing of machines both (mechanical and electrical) by suppliers is done only after receiving confirmed order form the client. As such while making lay out ample provision for such changes must be provided in the beginning stage it self. In addition to above the lay out should have ample space for gardens and greenery, office building, security office, time office etc. Even space for a temple or Mosc especially when owner is a HINDU or MUSLIM. This fact can be verified that Hindu owned factory a temple is always constructed and similar is the case for Muslim owned factory. So my contention is that space for temple or mosc should be left at appropriate direction in the lay out plan. Summing up it will be noted that for making an ideal lay out under many constraints requires a lot of experience and skill. One has to gain 10 or 15 years of experience in the field in all activities involved in the process of production of a particular product along with thorough knowledge of socio-economic and political conditions of the area in which a particular plant is to be located.

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