ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
ABSTRACT Shelter is one of the three basic needs of mankind. As population Overgrowth resulting land land scarcity scarcity have projected projected multistoried multistoried structures in a wide picture. New methodology methodology of design and rapid rapid modification modification of structures has has developed in last 38 38 years. he method method which involves most most efficient design philosophy is LIMIT STATE METHOD and !ts merits.the limit state method gives the more preferable preferable data and re"uired necessary strata strata for # design of high rise structures.designing structures.designing of structures. And also the benefits benefits data for the design of high rise structures. !n this project we have adopted SAA$.pro software for seismic and wind load or forces % analysis and design of a five storey residential building .the building is located located in seismic &one ' on on a site with medium medium soil. designing the building for seismic loads in conformation conformation with !S !S 1893(part 1):2002%wind loads in conformation with IS 875(part 3):1987 and LIMIT STATE METHOD of design for slabs% footings and staircase in conformation with IS 4562000! !n addition to IS 4562000 interaction diagrams from S()'* have also been used. he structure is design based on the +A,S %and the theory of LIMIT STATE METHOD which provide ade"uate strength% serviceability %and durability besides economy.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
CONTENTS
1.
Nota Notati tio ons
2.
Intr Introd oduc ucti tion on
3.
Desi Design gn of slab slabss
4.
Analys Analysis is of struct structure ure
.
Desi Design gn of bea! bea!ss
".
Desi Design gn of colu colu!n !nss
#.
Desi Design gn of foot footin ings gs
$.
Design Design of stairc staircase ase
%.
Dra Dra&in &ings
1'.
(ibliogr (ibliogra)*y a)*y
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
NOTATIONS
A Asc Ast Ag Ac , ,f ,w , $ $f d f ck f y 0eff 01 0y 2 21 m (o Sv S v c bd c ma1 4 w 5 6c 6a
-
-
Area Area of steel of compression. Area of steel in tension. ross sectional area. Area of concrete. ,readth of slab. +ffective width of flange ,readth of web. ,readth of beam or shorter dimension of rectangular column. Over all depth of beam. hickness of flange. +ff. $epth of beam or slab. /haracteristic cube compressive strength of concrete. /haracteristic strength of steel. +ffective span. 0ength of shorter span of slab. 0ength of longer span of slab. ,ending moment. ,.2. along shorter span. 2odular ratio. Safe bearing capacity of soil. 2oment of resistance constant. Spacing of Stirrups. Spacing of bars. orsional 2oment. Nominal shear stress. Shear stress in concrete. $esign ,ond stress. 2a1imum shear stress in concrete with shear reinforcement. Shear force. $istributed load per unit area. otal load. /ritical load. Actual neutral a1is.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Introduction
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
I"TROD#CTIO" he objective of structural design is to plan a structure which meets the basic re"uirements of structural science and those of the user. he basic re"uirements of structural design are safety serviceability% durability and economy. !n this project work it is proposed to design a multistoryed residential building consisting of 7 floors. +ach floor consists of 7 flats. he building is served by one stair case. I!)ortance of +ultistoried (uildings,
he rapid increase in population and !ndustrial growth and of shelter there is considerable rise in the price of shelter there is considerable rise in the price of city land and as the space is limited% hori&ontal e1pansion is difficult. ence vertical e1pansion has become compulsory. his has led to the conception of apartments or flats. An apartment consists of 3 to 9 storeys and each storey may accommodate : to 7 tenentments. he land and other amenities of apartments are shared by all the occupants. As our country is in developing stage% the economy of people may permit to ac"uire costly flats. ence for low income group% 0! flats are within reach and are most preferred. 2ulti storeyed building has been broadly classified into five types • • • • •
0oad bearing constructions. /omposite /onstructions. ;ramed /onstructions. #einforced /oncrete framed /onstructions. Steel framed /onstructions.
he first method has got the limitation that it will be economical only up to : to 3 storeys. ,y means of composite constructions techni"ue% the economy is achieved if the number is in between 3 to <. Any building having more than * storey=s has to be dealt by
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
means of framed constructions building having more than * storeys has to be dealt by means of framed constructions. Ad-antages of ra!ed Constructions o-er ot*er ty)es,
'. ;oundation cost will be lesser due to reduction wall thickness. :. /onsiderable speed is achieved in the reaction of building. 3. ;loor area will be more due to reduction in thickness of walls. 7. reater gla&ing area can be obtained. <. his type of construction permits removal or change of partition walls to suit varying re"uirements. Structural Descri)tions,
he building has to be four storeyed with plinth area of and served by one lift > staircase. he 4arious loads considered in the design of this building are dead load% live load. As the height of building is not more than '.< times the least lateral dimension% wind load is not taken into consideration in the design of this building. +arth"uake loads are not considered in the design of this building. Descri)tion of Structural Analysis,
Structural analysis is a branch of physical sciences which deals with the behavior of structures in given design conditions. Structures are defined as the systems that carry loads% and the word behaviour is understood to be their tendency to deform% vibrate% buckle or yield% depending upon the conditions confronting them. he results of analysis are used to determine the deformed shape of structures and to verify their ade"uacies is to carry the loads for which they are being designed. /onsidering that the deformation is the summation of strains and yielding is the e1cess and further considering that stress and strains are related to each other by the modulus of elasticity ?+=% the analysis of structures% thereby% reduces itself to the determination of the state of strain and or stress throughout the structures. Since the stress stresses% on the other hand% are the limiting values of internal forces% what actually remains to be done is the evaluation of internal force in the system.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Structural analysis along with stress analysis and design are the three basic topics with which structural engineering is primarily concerned. All% inspite of being so inter) related% are so distinct that they are often studied independently. 5hen the static e"uilibrium e"uations alone are not sufficient to analy&e a structure% the use of displacement compatibilities which rely on the physical properties% of the structure become imperative. 5hether the e"uilibrium e"uations alone are sufficient or not% the results of analysis must always satisfy the following three conditions '. +"uilibrium :. /ompactibility 3. ,oundary Normally there are two kinds of e"uilibrium) static and dynamic e"uilibrium. 5hen the loads are applied on the structure in a "uasilinear fashion @starting from &ero and reaching their final stage gradually% the structure will deform under these loads and will rest in its final shape. ;rom here on% the structure might change neither its position nor its deformed shape. his called the static e"uilibrium position of the structure. o the contrary% if loads are applied suddenly% the structure will undergo different deformation at different times. At any particular time% any particle or any portion of structures is in e"uilibrium under e1ternal loads% gravity forces% sporing forces and inertia forces act on that portion of the structure. his is the so called dynamic e"uilibrium. he compatibility principle assumes that deformation conse"uently displacement% of any particular point of the structure is continuous and single valued. he last condition specifies the way a structure is supported and is specified either in terms of forces @nodal forces or member forces or in terms of displacements. Classification of Structures:
A structure in general% composed of interconnected members which% regardless of their shape% are one% two or three dimensional. Actually% a member has always three dimensions length% width and thickness. owever% if width and thickness are small in comparison with the length% as in the case of beams and columns such members can be considered one dimensional or in the case of plates and shells% thickness is normally smaller than the length and width of the member. As for the ratios between length% width and thickness there is no clear)cut limit to them in accordance with which a member may be entirely classified as one% two% or three dimensional. his is entirely up to the engineer=s judgement and to the e1ecuted accuracy of the results.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
he structures can be divided into the following three categories by considering their members as one% two or three dimensions. '. Skeletal structures. :. Stressed)skin structures. 3. Solid 5hile the structural analysis relies heavily upon the principles of statics% the stress analysis is treated in disciplines such as strength of materials% mechanics of materials% and theory of elasticity. Structural design on the other hand makes sure that nowhere in the body do the stresses e1ceed their allowable limits. o accomplish this% it modifies the structure and re"uires that the analysis be repeated all over again. he cycle then continuous until no modification is re"uired. According to this cycle% the goal is to design a structure% and the structural analysis is one of the tools to achieve such a goal. #egardless of the analysis% the output is uni"ue and depends on the input only. Orientation,
Orientations means setting plan of proposed building in such a manner and direction% that the occupants of building would enjoy whatever is good and avoid whatever is bad from natural agency such as Sun% 5ind and #ain.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
to indu (rinciples% should not SOB. also that% if another constructed this house) north% then objection in face of towards ;or good the placement of different rooms in a house should be as follows-) '. ,+S ;A/!N O; OBS+ O5A#$S NO# O# 5+S :. ,+$ #OO2 ) SOB 5+S
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According Orthodo1 a building face ,ut it is mentioned there is house in front of facing there is no having house SOB. orientation%
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
3. SB$C #OO2 ) NO# 7. D!/+N ) +AS <. #OO2S 2OS0C BS+$ $B#!N $AC !2+ ) NO# @O# 5+S *. SA!# /AS+ AN$ /A##!A+ ) 5+S 9. $!#+/!ON O; 0ON+# OB+# 5A00S ) NO#)SOB $!#+/!ON 8. $!#+/!ON O; SO#+# OB+# 5A00S ) 5+S $!#+/!ON E. SOB S!$+ 5A00 ) A4+ /AFFAS @O# 4+#AN$A 'G. 5+S S!$+ 5A00 ) /AFFA ,B ON0C 4+#AN$A ''. 5!N$O5S ) +AS AN$ SOB ':. 4+#AN$A ) SOB AN$ 5+S ;acing of the ouse is known from the direction of longer wall of the front 4erandah. /rinci)les of /lanning and Designing,
he residential buildings need to be planned according to the kinds of occupants and the particular category o buildings. he dwellings of the type of houses and blocks of flats need to be planned on the basis of a family as a unit. owever the number of persons% their age and relation vary largely among the re"uirements in accommodation therefore have to be provide accordingly. (arents with children% childless couples% singly persons or widower% old couples and son on would be the kind of occupants% no hard and fast rules or particular standards of accommodation can be laid downH however certain desirable re"uirements are given here. Bnder normal circumstances% in addition to a living room% dining space% kitchen% other utilities such as stores etc% and sanitary units% provision of bedroom% dining in view of the si&e of family has to be made. A bedroom when singly bedded should usually have an area of 'Gs".m with a bare minimum of Es".m and a double room has an area of '< to '*s".m. ;ollowing are the suggestions of providing number of bedrooms. SNo.
Si&e of family
$esirable number of bedrooms Page 10
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
'.
A couple @alone
: single or' double bedroom
:.
A couple with '
3.
A couple with :
7 single or ' double and children : single
7.
A couple with 3
< single or : double and children ' single.
3 single or ' double and child. ' single
0euire!ents of /arts of (uildings, $%&'t-
he plinth shall be located with respect to the ground level such that ade"uate drainage of the site is assured. !t shall not be less than 7< cm from the surrounding round level. +very !nterior courtyard shall be raised at least '< cm above the level of the center of the nearest street and shall be satisfactorily drained. L&&'* R++,--
!t is a room% which is also referred to as ?$rawing room or $rawing all= parlor of main living room and service many varied purposes. !t is a lounge for rela1ing family members% a place for reception given to an occasional guest and may even provide for some work done by the family members. his room is the main area of contract with visitors and should% therefore preferably be located near the entrances. An important factor in arranging the living room is due consideration to seating accommodation of different groups. he best way to determine the si&e is to make layout sketch assuming the number of persons in the family plus two visitors. owever all the time this type of date is not available. here is practice to reckon the dwelling up to units with one or two bed room should be as '<)'* s" m however. '8):G s" m is considered better. !f dining space is to be provided in the living room% an additional floor area of 8 to Es".m is re"uired. D&'&'* R++,-
!n a house the floor area of a separate dining room depends on the type of furniture and the number of persons to be served at a time. !t should not be less than '7 s" m with a minimum width of 3)3.'< m. enerally the dining tables are having '.'Gm width though occasionally G.9< m tables are used. *Gcm of table length per person should be allowed for straight table% but when chairs are to be placed t ends% additional length of :G cm to 3G cm is necessary at both the ends to accommodate dished behind the chairs is G.*)9< m. he space for dining in this why is usually provided in the kitchen itself% e1cept in the housed of large families and rich people. owever% it is available even in case of every small housed to operate eating and cooking it possible. he width of such Page 11
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
dining room should be :.< m as minimum% for two rows of dinners facing each other with sufficient about G.*)G.9 m. ,ut it is better to plan such rooms considering possibility in future when table and chairs may be used. he dining room may also serve alternative purposes such a children=s study room% occasional sating room for ladies etc. !t should be well lighted and ventilated. .&t/'--
!n every house kitchen is one of the important rooms. he primary function in the kitchen or food preparation and service and may accommodate in addition to these% dining% cleaning of plates and lastly but not least child)care% the cooking in sitting position% despite good planning is most uncomfortable and laborious affair and dangerous as well. 5henever a new kitchen is being planned it should provide for cooking in standing position. he height shall be :.9< m measured from the surface o floor to the lowest point in the ceiling e1cept that portion to accommodate floor trap of the upper floor. he area of kitchen where dining is provided shall not be not less than
As a principle bedroom should not accommodate more than two persons. he bedroom should be oriented in the direction of prevailing wind @particularly in summer and be provided with bathroom cum dressing room if possible. owever the economy does not permit this% the bedrooms% a water closets are very essential in the bedrooms they are not only economical at initial stage but save floor space also. he planning of the bedroom depends on its singular of overlapping activities% and re"uired furniture. he bedroom may also serve the purpose of Sitting room% study room etc. ,edroom should be rectangular and in width not less than the length of the bed plus celandine of about '.: m for passage and place of furniture if any. !f the bed is placed sideways then the width of bed G.Em plus the same :.' m windows should be located where ever possible in the long wall and with higher still level than in the living rooms% reaching the permissible height for lintel level. As per municipal ,ye)0aws the minimum window area re"uired is one tenth of the floor under)ground drainage is not available% @5here area is not with ample the end of long wall preferably with a single shutter. !n any case no ,edroom shall have area less 'G s" m. Batr++,--
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Now a days it is considered ,edroom without an attached bath room is useless. owever the economy may not permit such provision and single ,ath room should provide with e"ual access for all ,edroom si&e '.7< m 6 '.: m. !f not water boiler is to be accommodated inside the ,athroom G.* m additional length is re"uired besides special provisions for drought and ventilation a ,athroom containing hot water boiler should have preferably a si&e of '.< m 6 :.7 m. ,athroom should consists of gla&ed tiles or polished flag stones% side walls should have aligning of flag stones for a height of G.E)'.: m a door for ,athroom should not be less than G.*< m clear% it should have a single shutter and hung in such a way% that when open shall screen the place when the actual bath is taken. No room containing water closets shall be used for any purpose e1cept as a lavatory ad no such room shall be open directly into any kitchen or cooking space by a door% window or other opening. i !t shall have minimum headroom of :.: m. ii A ledge or tank in a habitable room shall not cover more than :
!t shall have minimum headroom of :.: m. he minimum si&e of me&&anine floor if used as a living room shall be E.< m. he aggregate area in the building shall not e1ceed 'J3 of plinth. !t should be provided with standards of livings room such as lighting% ventilation and shall not be divided into smaller compartment nor shall be used as a kitchen. St+r R++,-
he height shall not be less than :.: m.
ara*-
he height of garage shall not be less than :.7 m. (rivate garage- A minimum of :.< 6 < m. (ublic garage- !t depends on the number of vehicles parked.
Ba-,'t--
he basement shall not be used for residential purpose. owever there can be used for storage of household and other goods of ordinarily combustible material% strong rooms% and bank cellar% air)conditioning e"uipment% other machines and parking spaces. he basement shall be minimum :.7 m height from the floor to undersides of roof slab. Ade"uate ventilation is a must% the minimum height of the ceiling of any basement shall be G.E m minimum and a ma1imum of '.: m above round level drainage should be Page 13
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
taken care off also seepage from underground and the access ground level should be taken care off. $arapt:
(arapet walls > handrails provided on edges o roof terraces% balcony% verandah etc. shall not be less than '.G< m and not more than '.: m in height room the finished floor level. Ca&'--
he si&e shall not be less than 3 m:. he clear passage within the divided space of any floor shall not be less than G.9< m and the distance from the farthest points place in cabin to any e1it shall not be more than '8.< m. B+'ar a%%--
he re"uirements of walls are as follows-) i he ma1imum height of compound wall shall be '.< m above the center live o the front street. /ompound wall up to :.7 m height may be permitted if the top G.E m is open type construction of design. ii !n case of a corner plot the height is G.9< m for a length% 'G m on front > sides and the balanced height of G.9< m if it may be in accordance with @a
Sta&r Ca--
he minimum widths of staircase area #esidential buildings '.G m b #esidential hostel building '.< m c Assembly building '.< m d +ducation buildings '.< m e !nstitutional building :.G m f All other buildings '.< m he minimum width of treat without nosing shall be :< cm for residential building and 3G cm for other buildings. he ma1imum height or riser shall be 'E cm for residential building and '< cm for other buildings and there shall be limited to '< per flight. he minimum head room in a passage shall be :.: m. R++--
he roof of a building shall be so constructed of framed as to permit affective drainage of rain)water therefore by means of sufficient rainwater pipes of ade"uate si&e% thus preventing dampness. he rainwater popes may be connected to drain or sewer tat > termite proof.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
S'-a--
!t is the sloping @or structural hori&ontal overhang which is usually provided over openings in e1terior walls. heir purpose is to provide protection from sun and rain. L&*t&'* ;'t&%at&+':
hese should have provisions for admission of light I air such as window > ventilators% opening directly to e1ternal air or into an open verandah with a ma1imum width of :.7 m. notwithstanding the area of opening the minimum aggregate area of such openings e1cluding doors and inclusive of frames. a 'J'Gth of floor area for day hot climate. b 'J*th of floor area for wet hot climate. c 'J8th of floor area for intermediate climate. d 'J':th of floor area for cold climate. C+%+r Ar/&t/tr-
he building may be structurally stable. ,ut it is the colour% the perception o which is attributed to human eye at first sight. he most important and predominate factor that acts an interior decoration is the coloring scheme of walls and ceiling. /olour creates a dramatic bold background. A dull cold room can suddenly become warm and gay @0ight hearted cheerful% simply by using red @or orange colour. ;or rectangular building% a length- width ratio of '.:-')'-<-' is to be generally followed. A room% with length longer than '.< times the breadth will give tunnel effect and hence should be avoided. Similarly a small room with large ceiling height will produce a cavernous effect. ence room should be will proportioned. owever% at times it may not be possible to satisfy all these measurements% !f% due to any reason% it necessities to adopt for wrong proportional to length - width - height% the resulting bad effects can be minimi&ed by adopting suitable co lour architecture to individual rooms according to their purpose as ,ed room% living room% study room etc. Architecture is a visuals art. ;or vision% light is essential whether it is direct @or indirect% natural @or artificial. Appr+a% + p%a':
he approval of plan means the acceptance of local authority of the following re"uirements onlyArrangement of stairs% lifts% corridors% doors% windows and parking i eight of building and its various storey=s. ii 2inimum re"uirements with respect to areas of rooms. iii 2inimum re"uirements with respect to areas of rooms. iv 2inimum re"uirements of sanitary facility. v (ermissible built up area vi (ermissible ;.S.! @floor space !nde1 vii (ermissible open space > set)back viii (ermissible use of buildings
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
i1
(rovisions for light > ventilation
STR#CT#RAL DESI"
Structural design is an art and science of designing serviceable and durable structures with economy and elegance. he entire process of structural planning and design re"uires not only imagination and conceptual thinking but also sound knowledge of science and structural engineering% knowledge of practical aspects such as relevant design codes and bye)laws backed up by ample e1perience in tuition and judgement. /onstruction is an ultimate objective. An engineer is key person for successful completion of any kind of project undertaken. ence he should adopt all means to reduce cost of project to minimum% without unduly reducing the serviceability aspect of the project. An engineering structure is an assembly of members for elements transferring the load and providing a form% space% enclosure and or a cover to serve the desired function. he objective of structural design is to plan a structure which meets the basic re"uirements such as serviceability% safety% durability% economy% aesthetic beauty% feasibility% practicability and acceptability. $rp+- + -tr/tra% -&*' -
he purpose of structural design is% providing a safe structure with user=s re"uirements. he design should evolve a structural solution for safety and serviceability throughout the design life% which gives the greatest overall economy for the first cost and for maintenance cost. Satisfactory design must ensure the achievement an acceptable probability that the specified life of a structure is not curtailed permanently due to attainment of an unsatisfactory serviceability condition called K0!2! SA+L. he acceptable probability should be chosen in such a way that a satisfactory balance is achieved between the cost of a possible structure and serviceability failure. Aa'ta*- + L&,&t Stat Mt+-
!t is a concept including some constants which are arrived at% after a series of e1perimentation and also out of e1perience of many senior engineers% architects etc. 0imit states are concerned with structural safety and serviceability and covers all forms of failure. A structure could be rendered unit in many ways and these factors are conveniently grouped into main categories. a B0!2A+ 0!2! SA+- /ollapse of the structure due to normal or severe loading on the occurrence of catastrophic events like earth"uakes etc. b S+#4!/+A,!0!C 0!2! SA+- $eflection% cracking and vibration. c O+# 0!2! SA+S- ;atigue% durability% fire resistance% lighting etc. !t is often possible that a given structure is re"uired to satisfy one or more limit states simultaneously. he usual approach then is to design on the basis of the most Page 16
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
critical limit states and check for the other limit states. 2any times% satisfying one of one limit state would satisfy other limit states. ;or e.g.% a structure is designed to keep the limit states for cracking within acceptable value% the limit for durability is also simultaneously satisfied. he concept of limit state provides a rational approach taking into account% variations in material strength and loads. his is in fact a rationali&ation of the ultimate load. ;our reasons to justify the design of structures by limit state method arei /oncept of separate partial safety factors of loads of different combinations in the two limits state methods. ii /oncept of separate partial safety factors of materials depending on their "uality control during preparation. hus% Mm for concrete is '.< and the same for steel is '.'<. his is more logical than one arbitrary value in the name of safety factor. iii A structure designed by employing limit state method of collapse and checked for other limit states will ensure the strength and stability re"uirements at the collapse under the design loads and also deflection and cracking at the limit state of serviceability. his will help to achieve the structure with acceptable probabilities that the structure will not become unfit for the use for which it is intended. iv he stress block represents in a more realistic manner when the structure is at the collapsing stage @limit state of collapse subjected to design loads.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Analysis &Design of Slabs (One-way & Two-way slabs)
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
SLABS eneral,
A Slab is a flat% two dimensional planar% structural element having thickness small compared to its other two directions. !t provides a working flat surface of covering shelter in buildings. !t supports mainly transverse loads and transfers them to supports primarily by bending action in one or more directions. he #././. slab is essentially a bending moment% like a beam% though it differs from beam with respect to followingi he bending is in more than one vertical plane. ii he slab is designed as a strip of 'm wide. iii Shear stresses are usually low and shear reinforcement is not provided. owever it is critical in flat slabs. iv $istribution steel is provided right angles to main fle1ural reinforcement to take care of temperature and shrinkage stresses. +et*od of Analysis:
he behaviour and strength of slab depends upon% the shape and geometry @span% support and boundary conditions% loading level @service load% ultimate load the state stress @elastic% in elastic% plastic. !t may be noted that analysis of slabs is e1tremely difficult due to number of variables stated above with the result that rigorous or e1tract method are not available and therefore analytical% semi empirical methods are developed @!S 7<*):GGG allow design based on e1perimental investigations. Classifications of Slabs,
Slabs are classified on the basis of the following'. Shape @rectangular% circular > other shapes. :. Support and boundary conditions @single span slab known as one slabs% slabs supported on 7 edges known as two way slab% overhanging or cantilever slabs% simply supported slabs% slabs fi1ed or continuous at one or both ends. 3. ype of support- simply supported on walls% slab cast monolithically with the supporting beams% slabs supported directly on columns @flat slabs.
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
7. Spanning direction- simply supported slabs% slabs fi1ed or continuous at one or both ends. <. Bse @roof slab% floor slab% wall slab% foundation slab etc. *. Sectional configuration- solid slab% ribbed plate% waffle plate% stiffened plate% corrugate plate% folded plate. Solid slab is a flat hori&ontal plate without ribs or stiffness. his is the most common type of slab.
S%/t&+' + -&ta% ,t+ +r -&*' + -%a a' /%a--&&/at&+' + -%a- +r t&pr+</t-
!.S code method which is described in Anne1)$ of the code !S 7<*):GGG is selected because of its simplicity and adaptability. 0imit state method is used for design of slabs. /lause :7.7% 39.'.: of !S code states% for analysis of slabs spanning in two directions at right angles yield line theory or any other acceptable method may be used. Alternatively the provisions given in Anne1) $ may be followed. he slabs are classified according to boundary conditions% ratio of 0yJ01% loading and span. A--,pt&+'- &' D-&*':
'. Bsing partial safety factors for loads in accordance with clause 3*.7 of !S)7<*) :GGG as Mf '. '.'< for steel. 3. Bsing partial safety factors in accordance with clause 3*.7 of !S)7<*):GGG combination of load. $.0. 0.0. @'.< $.0. 0.0. 5.0 @'.: 7. $ensity of material used in accordance with #ef @!S 89<)'E89MATERIAL
D'-&t
(lain concrete #einforced ;looring material @c.m ,rick masonry ;ly ash <. 0ive 0oads0ive load on slabs 0ive load on passage 0ive load on stairs
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:7 kNJm3 :< kNJm3 :G kNJm3 'E kNJm3 < kNJm3 : kNJm: 3 kNJm: 3 kNJm:
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
D-&*' C+'-ta't-:
Bsing 2:G > ;e7'< grade of concrete > steel f ck @/haracteristics strength for 2 :G :G NJmm: f y @/haracteristics strength for steel 7'< NJmm:
L+a +' -%a-: Da %+a:
Self)weight of slab- his load acts as B$0 and is calculated after assuming the 'm wide s"uare strip > suitable thickness by stiffness consideration. ;loor finish load- his load also acts as B$0 and is calculated after assuming suitable intensity over 'm wide strips.
L& %+a:
his is the temporary load on its intensity depends on type > occupancy of building. As per !S- 89< ) (art !4% the intensity of live load for this project is taken as :.< kNJm:
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
D-&*' O O' a S%a (S1) $r%&,&'ar Data
Short span 0ong span /lear cover to the reinforcement $iameter of the bar used Aspect ratio
01 G.88 m 0y 7.:E m d' :G mm P 8 mm 0y J 01 7.:E J G.88 7.89< ence the slab is to be designed as one way slab. Assume thickness of slab as ':Gmm.
G.88 m
7.:Em
Ca%/%at&+' + L+a-
0ive 0oad 5eight of slab 5eight of flooring 5eight of partition wall otal $ead 0oad otal 0oad otal ;actored 0oad +ffective length 2a1imum ,ending 2oment
: kN J m: G.':1'1'1:< 3.G kN J m: G.G<1'1'1:G '.G kN J m: 'kN J m: <.G kN J m: 9.G kNJ m: 5u '.< Q 9.G 'G.< kN J m: 0 eff G.88 m 2 5u0:J': 'G.<6G.88:J': G.*99*Dnm ;actored ,ending 2oment '.< 1 G.*99* '.G' kNm $epth of slab re"uired otal depth re"uired
d R@2JG.'38f ck b R@'.G'1'G*J@G.'381:G1'GGG 'E.':mm
dre"d 'E.': :G 8J: 73.': mm As dre"d d prov @'GG mm% the section is SAE Adopt overall depth ':G mm Ara + St% R=&r
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ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Ast G.
Assume 8mm dia bars A st = s dist =
a st s main a st A st
1 'GGG =
1 'GGG =
3.'7 1 8 1 8 1 'GGG 7 1 :
3.'7 1 8 1 8 1 'GGG 7 1 :G'.G*
= :G'.G* mm :
= :
As per clause :*.3.3b% spacing least of the followingH '. 3 Q effective depth 3 Q 'GG : also to abide by the clause of code% provide 8 ,, &a,tr H>SD Bar- a- ,a&' -t% at 250 ,, /?/ 8 ,, &a,tr &-tr&t&+' -t% at 250 ,, /?/!
C/@ +r Sar
Shear force
4u =
5u 0 1
Nominal Shear ;orce
3
=
'G.< 1 G.88
= 3.G8 kN 3 4u 3.G8 1 'G 3 = = G.G3G8 NJmm : v = bdV 'GGG 1 'GG Ast 1 'GG
(ercentage of Steel (t I = bdV = c G.3: c= k 1 c '.3 1 G.3: G.7'* NJmm:
Page 23
:G'.G* 1 'GG 'GGG 1 'GG
= G.:G I
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
v c=J:
(SAE)
C/@ +r D%+p,'t L'*t
Area of steel provided
A st =
'GGG 1 3.'7 1 818 7 1 :
= :G'.G* mm :
2oment of #esistance
2 r = G.89 f y A st dV−
f y A st
7'< 1 :G'.G* = G.89 1 7'< 1 :G'.G* 'GG − f ck b :G 1 'GGG = *.E< kNm G.89 f y W
$evelopment length re"uired
0 d% re"d
$evelopment length provided
0d% prov =
=
7 bd
2' 4u
=
+ 0G =
G.89 1 7'< 1 8 7 1 @'.* 1 '.:A
*.E< 1 'G* 3.G8 1 'G3
0d%prov X 0d%re"d(SAE)
Page 24
=
39*.GE mm
+ 'GG = :3<*.< mm
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
D-&*' O T+ a S%a (S2) $r%&,&'ar Data
Short span 0ong span /lear cover to the reinforcement $iameter of the bar used Aspect ratio
01 :.'7 m 0y 7.GG m d' :G mm P 8 mm 0y J 01 '.8*
:.'7 m
7.Gm
ence the slab is to be designed as two way slab. Assume thickness of slab as ':Gmm Ca%/%at&+' + L+a-
0ive 0oad 5eight of slab 5eight of flooring 5eight of partition wall otal $ead 0oad otal 0oad otal ;actored 0oad
: kN J m: G.':1'1'1:< 3.G kN J m: G.G<1'1'1:G '.G kN J m: 'kN J m: <.G kN J m: 9.G kNJ m: 5u '.< Q 9.G 'G.< kN J m:
B'&'* M+,'t C+&/&'t- @from table :*
Y1@ G.G89 Yy@ G.G3<
Ca%/%at&+' + D-&*' M+,'t-
Negative ,2 at Support
(ositive ,2 at 2id Span $esign ,ending 2oment
Y1@) G.G*8 Yy@) G.G79
2u1 G.G89Q'G.
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
Dpt R=&r r+, Ma&,, M+,'t Cr&tr&a
+ffective depth re"uired deff R@2uma1J@G.'38f ck b R@<.31'G*J@G.'381:G1'GGG 73.8:mm otal depth re"uired% dre"d 73.8: :G 8J: *9.8: mm As dre"d d prov @':G mm% the section is SAE Adopt overall depth ':G mm.
Ara + St% R=&r 2
G.89 f y A st @d
=
G.7: f ck bd : JA st
−
Ast re"uired for )ve 2oment at Supports% Ast1 '<'.<* mm: Asty 8G.*G mm: Ast re"uired for ve 2oment at 2id Span% Ast1 ''3.<' mm: Asty
(rovide 8 mm diameter bars @distribution steel at : also to abide by the clause of code%
)ro-ide $ !! dia!eter SD (ars as !ain steel at 2' !! c5c 6 $ !! dia!eter distribution steel at 2' !! c5c. C/@ +r Sar
Shear force
4u =
5u 0 1
Nominal Shear ;orce
3
=
'G.< 1 :.7'
= 8.73< kN 3 4u 8.73< 1 'G3 = = G.G873 N Jmm : v = bdV 'GGG 1 'GG Ast 1 'GG
:G'.: 1 'GG
= = G.:GI (t I = (ercentage of Steel bdV 'GGG 1 'GG c G.3: c= k 1 c '.3 1 G.3: G.7'*. (SAE) v c=J:
Page 26
ANALYSIS & DESIGN OF A MULTISTORIED RESIDENTIAL BUILDING
C/@ +r D%+p,'t L'*t
Area of steel provided Ast @'GGG13.'71818J@71:
=
G.89 f y W 7 bd
G.89 1 7'< 1 8 =
7 1 @'.* 1 '.:A
$evelopment length provided 0d%prov '.3 2'J4u 0G '.3@*.E*1'G*J@7.:'91'G3 'GG ::7< mm (SAE) 0d%prov X 0d%re"d
Page 27
=
39*.GE mm
