CHAPTER 3 SUPERSTRUCTURE DESIGN
3.1. Structural Design Methodology and Audit Audit Superstructure design was carried out systematically in two stages - preliminary and detailed design, in order to produce the optimum design for the client. Finite Element Analysis (FEA) was employed for most of the structural design and analysis, especially through ETABS and SAFE. Lastly, the manual design calculations were developed for cross-checking and design audit purpose. The flow chart below illustrates the structural design methodology that has been adopted for the entire design process. The design methodology is summarised in Figure 3.1 bellow.
Figure 3.1: Structural design methodology and audit
3.2. Codes and Standard for Detailed Design Below are the code and standards used for the superstructure detailed design, British Standard are the main references especially for RC and Steel design.
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Concrete design
BS 8110:1997
Steelwork design
BS 5950: Part 1
Weight of materials
BS 648
Imposed loads
BS 6399: Part 1
Section shapes
BS 4848: Part 4
UBBL
1984: 2010
Foundations Foundations
BS 8004 (1986)
Site investigation investigation
BS 5930 (1999)
3.3. Preliminary Design (Finite Element) Element) Using ETABS Integrated Building Design Software (ETABS) is a Finite Element software produced by Computer and Structure Incorporation (CSI) to analyze the building performance and structural design of vertical elements such as columns, walls and foundation system based on Finite Element Method. The initial sizing of vertical members was obtained by manipulating the concrete grades, member size, reinforcement bars, location of support and etc.
After obtaining the preliminary sizing of vertical elements, the detailed design of RC flat slabs was carried out in SAFE - Structural and Earthquake Engineering Software. SAFE is widely used for modeling of RC flat slab, analysis, designs & preliminary sizing based on Finite Element Method
3.4. Detailed Design of Slab System System Functions: Modelling of reinforced concrete flat slabs and beams, analysis, designs and preliminary sizing using finite element method.
3.4.1
Design procedure of flat flat slab system using SAFE (e.g. Level Level 7)
Step 1: Tracing of structural elements from architectural drawings
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Figure 3.2: Architectural drawing (Level7)
Figure 3.3: Tracing of structural elements
Step 2: Import scaled drawing into SAFE
Figure 3.4: Scaled drawing - Imported into SAFE
Step 3: Define and assign materials properties
Structural Properties Slab Properties Beam Properties Column Properties
= = =
S275 No beam C300
(Thickness 275mm) (Flat slab system) (Rectangular column 300mm x
300mm)
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Wall Supports
=
W200
(RC walls thickness 200mm)
General Properties Modulus of Elasticit y = Poisson Ratio RC Unit Weight Concrete Concret e Cover Concrete Concret e Strength Strengt h Reinforcing Yield Stress
Step 4:
27 kN/mm² = 0.2 = 24 kN/m³ = 40 mm = 35 N/mm² = 460 N/mm²
Define loading schedule
Dead Load
=
Self weight of slab
(24 kN/m³)
Live Load
= =
2.0 kN/m² 0.75 kN/m²
(BS 6399: Part 1 - Normal functions)
(Roof - Maintenance purpose)
Superimposed Superimposed = Dead Load (SDL)
1.0 kN/m²
wall partitions + screed / ( Brick wall
Special Case (SDL) = 5.0 kN/m²
=
26.0 ~ 28.0 kN/m²
=
(Roof Garden - Assume 50cm thick soils) 7.5 kN/m² (M&E - Assumptions w/o specifications)
finishes) (Roof water tank)
Step 5: Define analysis options
Load Combination
= =
SLS (serviceability (serviceability loads) - Checking of deflection DL x 1, LL x 1, SDL x 1 ULT (Ultimate loads) - Structural Design Purpose DL x 1.4, LL x 1.6, SDL x 1.4
Static Load Case
Step 6: Assign structural elements, imposed & transferred loads
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Figure 3.5: An example of flat slab model in SAFE (Level 7) Step 7: Checking of slab deflection
After running the finite-element analysis, the slab deflection is checked under two deflection . different conditions - elastic uncracked deflection and long term crack deflection. As displayed in the deflection contour diagram (Figure 26), the slab deflection under long term crack condition is more critical than the elastic-uncracked condit condit ion, due to the effect of creep and shrinkage. Therefore, for design purpose, the long-term deflection was checked in accordance to the BS code, which specified that the maximum slab deflection between two unsupported span should not more than L/250 or maximum 40mm, whichever is smaller. In case of excessive deflection,
several factors were manipulated including concrete grade, slab thickness, vertical support and so on, until it fulfils the requirements.
Figure 3.6: Slab deflection under serviceability loads
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Figure 3.7: Slab deflection under serviceability loads Following on the procedures explained above, the analysis and design was carried out for the whole building (top roof to ground floor):
3.4.1. Design Summary
3.4.2. Special Design Considerations
Case 1: Top Roof Due to the critical loads imposed by the roof water tank, the slab deflection was critical even though the slab thickness has been increased to 300mm, with concrete grade 50. So instead of keep on increasing the slab thickness, RC beams were introduced for a more economic design, and in the end the deflection was kept within the limit as shown below:
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Figure 3.8: Introduction of RC beams Case 2: Level 2: Level 3 and Level 4
Figure 3.9: Variation of slab thickness due to different functions and loads Case 3: Level 3: Level 2 At level 2, critical deflection occurred at the 13m span car porch supported by the columns alone at the slab edge, so we introduced steel beams to resolve the issues in order to look after the aesthetic value. RC beams are not practical in this case as it will be very deep in size and indirectly reduce the clearance height for the car porch.
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Figure 3.10: Critical deflection at 13-m span car porch
Figure 3.11: Deflection controlled through steel beam support Case 4: Level 4: Level 1 Due to the structural requirements, additional columns are proposed at the ground floor lobby area to cater for excessive deflection.
Figure 3.12: Location of proposed additional columns at the ground floor
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3.4.3. Slab Reinforcement
For the slab reinforcement bars, the minimum reinforcement as specified in the BS 8110 is 0.13% of the total cross-sectional area. To facilitate our calculation, the slab was designed based on the per meter strip, we provided T12 @ 200 for the basic rebar, top and bottom in X and Y direction, d irection, in order to fulfill the requirements.
Consider per meter strip: BS 8110
=
Minimum Reinforcement Reinfor cement 0.13% bh =
0.13 % x 1000mm x 300 mm (max. slab thickness)
=
390.0 mm²
Provide T12 @ 200 for basic rebar
=
565.0 mm²
Figure 3.13: Typical drawing of slab basic rebar On top of the basic rebar, additional reinforcements are required at certain area where the bending moment and shear force are critical. To come out with a more accurate and economic design, SAFE was used to generate the amount and location of additional rebars on top of the basic rebar, based on per meter strip. The diagram below illustrates an example of additional top rebar near to the column support at level 7 slab, where higher number of compression bars are required due to the critical flexural stress at the slab.
Thus, for one piece of continuous RC slab, the additional rebars will span in X and Y direction, top and bottom of the slab. The final output of the design will be basic rebars spanning each-way and each-face of the slab, plus the additional rebars at certain area where there are excessive bending moment and shear force. The diagram below illustrates the detailed drawing of additional top reinforcement bars in addition to the basic rebars at level 7. 25
3.4.4. Risk Assessment & Special Design Considerations
Risk assessment assessment 1: 1 : Punching shear failure Reference:
Behavior of Reinforced Concrete Flat Slab, P.E. Regan, CIRIA
Report 1989 Punching Shear 1) Most critical consideration considerat ion in flat plate design around the columns 2) Punching at a single column causes a major redistribution redistribut ion of load effects, and lead to potential progressive collapse 3) Instead of using thicker section, shear reinforcement in the form of shear heads, shear studs or stirrup cages may be embedded in the slab to enhance shear capacity at the edges of walls and columns 4) Drop panel is utilized to thicken the slab locally locall y to eliminate eliminat e punching shear failure 5) All critical columns at the building were checked against the punching shear failure, the top roof columns are exposed to punching shear 6) Based on the design calculat ion ( Appendix C ) the slab thickness was increased locally by providing the drop panel and shear studs to eliminate this issue.
Risk assessment assessment 2: 2 : Holes Adjacent to columns - Trimmer Bars for Slab Openings Reference:
Design of Reinforced Concrete Flat Slabs to BS 8110, Report 110
(2nd Edition) - R T Whittle MA Ceng MICE “ In
the flat system, holes should not be placed at the column face, as they
considerably reduce the moment transfer in one or both directions. Even if torsion links are provided in the slab adjacent to the column, it does not develop its design couple until large rotations occ ur”
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Figure 3.14: Holes adjacent to columns in flat slab system When it is necessary to cut bars to fit a hole, replacement bars of the same diameter should be positioned along all sides of the hole. All replacement bars should extend a tension anchorage length beyond the edges of the hole.
Risk assessment assessment 3: 3 : Concrete Cover - Fire Rating Architect’s r ecommendations: ecommendations: -1 hour fire rating -BS 8110 Part 1, Clause 3.3.6 - corresponding to minimal cover of 20 mm for continuous slab Our recommendations: recommendations: -25mm (20+5) for all slabs and columns except: -For all concrete concret e faces in contact with water or soil =
Cover 40mm
(Applicable (Applicable to ground floor slab & top roof slab) 3.4.5. Manual Design Design Calculation Calculation for Flat Slab Design
Refer to the folder name superstructure design in the attached CD.
3.5. Detailed Design of Column System 3.5.1. Column Column Reactions based on on the SAFE SAFE Output - Finite Finite Element Method
The ultimate column reactions were obtained from the SAFE output (Figure 45) as it is more accurate and precise compared to the approximate area method. The cumulative loadings for all floors are enclosed in Refer to the folder name superstructure design in the attached CD.
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Figure 3.15: Column reactions generated from SAFE To carry out the design, we have developed our own spreadsheet (attached in the CD) and design calculations (attached in the CD). The design summary is shown in the table below: Table 3.1: Design summary for RC columns
The RC columns were designed for the whole building based on the most critical ultimate loads obtained for each floor. The smallest column size is 300 x 300 for the top roof and increased gradually to 525 x 525mm at the ground floor, all using concrete grade 35.
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We have tried to manipulate the concrete grade but apparently it did not helped much in reducing the column size, therefore we decided to use the same concrete grade for all level to minimize variations and facilitate the construction on site as well. Basically there were no any changes to the proposed column location in the architectural drawings, but additional columns are required to be introduced at ground floor to cater for slab deflection. As explained, the column dimension can be standardized for the whole floor to minimize variations and facilitate the contractor contr actor’s works, but it is not cost efficient as the column size was designed based on the most critical load. Therefore, we carried out some value engineering by designing the column size in batches based on the loading range, and 5 t ypical column sizes were produced pro duced for the whole building. Based on our study, the proposed method will produce some minor variation in the column size for a particular floor (Figure 48), and the same process was repeated for the whole building (Table 5). The tabulated results shown that the second method will save the concrete volume by approximately 50%. Table 3.2: Design of columns by batches based on the loading range
3.5.2. Detailing of RC Columns
The detailing of the RC columns was carried out strictly in accordance to BS 8110, especially the main bars, links and hooks.
Detailing of RC Columns Columns - In Accordance Accordance to BS Code Code of Practice: Main Bars: Minimum Reinforcement Reinforcement
=
0.4% of Cross-Section 29
Maximum Reinforcement
=
6.0% of Cross-Section (Vertical Cast)
Maximum Reinforcement
=
8.0% of Cross-Section (Precast)
Minimum Bar Size
=
T12 or T13
Minimum No. of. Bar
=
4 for Square Column
=
6 for Circular Column
=
12 times the diameter diamet er of the smallest main bar
Links: Link Spacing compression Link Size
bar (Maximum 300mm) =
Not less than 1/4 of the largest compression compressio n bar
Hooks: To be provided if face bar is more than 150mm of restrained bar The detailed drawing for second method, where the column sizes were designed based on the loading range is shown in Figure.
Figure 3.16: Detailed drawing of column design (method 2) The typical detailing of RC column in cross-sectional view, especially the anchorage length and compression lap is shown in Figure 51. Hooks are provided when the spacing of the face bar is more than 150mm of restrained bar. 3.5.3. Risk Assessment & Special Design Considerations
Risk assessment assessment 1 : Connection between Columns and Flat Slabs - Lateral Stiffness Reference:
Design of Reinforced Concrete Flat Slabs to BS 8110, Report 110
(2nd Edition) - R T Whittle MA Ceng MICE “T he he
connection between the columns and flat slabs is unsuited to resist large
bending moments. Even if the moment capacity is sufficient, the maximum shear capacity is likely to be exceeded because of the effect of moment transfer. Thus,
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whenever possible, horizontal loading should be resisted by shear or core walls making the structure a 'no-sway' frame .”
1) Edge columns have limited moment moment transfer capacity capacit y 2) Internal columns resist most of the moment, but this reduce the shear shear capacity of the adjacent slab 3) Holes in the slab close to a column column and in the plane of bending drasticall y reduce the moment transfer capacity.
Due to this reason, the lift core was proposed to be converted as a shear wall (Figure 52 - yellow boxes ). Initially the staircase RC walls were suggested to be replaced with shear walls in order to obtain more uniform distribution of lateral stiffness, but apparently the idea was not feasible as there are windows at the staircase that might interrupt the structures.
Figure 3.17: Proposed shear wall locations
Reference:
BS 6399 Part 2: Code of practice for wind loads
Notional horizontal load load “ All
buildings should be capable of resisting a notional design ultimate horizontal
load applied at each floor or roof level simultaneously equal to 1.5 % of the characteristic dead weight of the structure between mid-height of the storey below and either mid-height of the storey above or the roof surface [i.e. the design ultimate wind load should not be taken as less than this value when considering load combinations 2 or 3.”
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According to BS 6399, it is mentioned that all buildings should be capable of resisting a notional design ultimate horizontal load which is equivalent to 1.5 % of the characteristic dead weight. This is not a compulsory requirement requirement for building less than 10 storeys, but we carried out the analysis by using ETABS to analyze the lateral deflection based on 1.5 % of the building dead loads (Figure 53). The deflection diagram shows that the lateral drift is approximately 46mm, which is below the lateral deflection limit as specified in the code (Figure 55).
Figure 3.18: Checking of lateral deflection through ETABS ( Finite Finite Element E lement Method)
Figure 3.19: Lateral deflection of the t he building
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Figure 3.20: Lateral deflection diagram of the building Risk assessment assessment 2: 2 : Precautions Precautio ns Against Progressive Collapse - Bottom Reinforcement at Joints Joints
Reference:
Behavior of Reinforced Concrete Flat Slab, P.E. Regan, CIRIA
Report 1989 “ As
a precaution against progressive progressive collapse occurring as a result of a punching
failure at a slab/column joint, and the consequent increases of shear and unbalanced moments at neighboring joints, some bottom reinforcement reinforcement should be provided at suggested that the amount of reinforcement reinforcement be determined by the all joints. It is suggested hat:” condition t hat:”
In order to mitigate the risk against progressive collapse, we have provided bottom reinforcement at all joints, especially the connection between RC slab and column. As shown in the drawing, the bottom reinforcement bars should span in both X and Y directions:
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Figure 3.21: Typical RC slab & column connection details
Risk assessment assessment 3: 3 : Safeguarding of Vertical Elements Against Vehicular Impact Reference:
BS 8110
Safeguarding against vehicular impact “Where
vertical elements are particularly at risk from vehicle impact, consideration
should be given to the provision of additional protection, such as bollards, earth banks or other device s”
The RC columns at the car porch are exposed to the risks of vehicular impact, which might lead to the collapse of the slab, therefore addition protection such as structural column protectors should be provided (Figure 57) .
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3.6. Detailed Design of Beams System 3.6.1. Introduction of of Minimal Minimal Beams Beams at the Building Building
For the beams design, there are a very minimal number of beams at the top roof and level two car porch due to the flat slab system (Figure 58). Based on the beam moment and shear diagram generated by SAFE (Figure 59 and 60), the designs and detailing were carried out in accordance to BS 8110.
Figure 3.22: Location of RC Beams
General Design Considerations and Detailing - RC Beams:
Based on BS 8110 8110 Simplified Rules: Rules:
1) Minimum areas of shear reinforcement reinforceme nt in beam - Table in BS code code of practice 2) Minimum areas of compression reinforcement for rectangular beam beam = 0.2% total areas of concrete 3) Minimum areas areas of tension tension reinforcement reinforcement for rectangular rectangular beam = 0.13% total areas of concrete 4) Maximum tension/compression reinforcement = 4% gross cross-section concrete 5) Minimum bar size = T12
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6) Beams whose depth 750mm or more should be provided with side lacers maximum 250mm spacing 7) Maximum amount of reinforcement in a layer including tension laps. At At laps, the total diameter of all reinforcement provided in a particular layer should not exceed 40% the breadth of the section at the level. 3.6.2. Manual Design Calculations
Design of RC Beams Beams based on: Refer to the attached att ached CD. 3.6.3. Design summary summary
Based on the design, the final beam sizes were determined to be 200 x 500mm RC rectangular beams, while steel beams were employed at level 2 car porches, as shown below. The diagram below shows the detailed drawing of RC beams and steel beam, including the reinforcement for tension and compression bars.
Figure 3.23: Detailed drawing of beams design The typical details for RC beams connection to the columns are illustrated below, which shows the anchorage length. 3.6.4. Risk Assessment and Special Design Considerations
Risk assessment assessment 1: 1 : Corrosion Resistance The risks associated with RC column-to-steel beam connection mainly come from the seismic loading, which is not applicable in our design. However, the steel beams
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supporting the car porch are exposed to weather conditions; therefore it should be protected by a coating, for example galvanized.
3.7. Other Design Considerations 3.7.1. Design of Parapet Parapet Wall Wall for Roof
Figure 3.24: Typical design of parapet wall Risk assessment assessment:: Moisture penetration problems The top of a parapet wall is vulnerable to moisture penetration problems. Choosing an appropriate cap is an effective way to eliminate this condition. A variety of materials are available to cap off the wall, with limestone, terra cotta, hard-fired clay, or precast concrete preferred. These materials have thermal properties similar to those of brick and concrete masonry. 3.7.2. Design of Plinth Details
A plinth is the base or platform upon which a column, pedestal, statue, monument or structure rests, it also refer to the mass topping of concrete blinding.
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Figure 3.25: Typical design of plinth 3.7.3. Design of Lintel Details
A lintel is defined as a structural horizontal block that spans the space or opening between two vertical supports. Typically above openings, a lintel is used, not a bond beam.
Figure 3.26: Plinth lintels details
Risk assessment assessment:: Construction stability Where concrete floors are to be placed onto lintel, the lintels should be supported temporarily until the floors have been completed to reduce the risk of shock loading or uneven loading of the lintels.
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3.7.4. Staircase Design
Figure 3.27: Staircase design 3.7.5. Lift Motor Motor Room Hosting Beam Details
Figure 3.28: Typical lift motor room hosting beam details 3.7.6. Lift Core Wall
Figure 3.29: Typical design of lift core wall
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CHAPTER 4 SUBSTRUCTURE DESIGN
4.1. Soil Investigation The design of a structure which is economical and safe to construct, is durable and has low maintenance costs, depends upon an adequate understanding of the nature of the ground. This understanding understanding comes from an appreciation appreciation of the distribution distribution of the materials in the ground, and their properties and behaviour under various influences and constraints constraints during the construction construction and lifetime of the structure. An adequate adequate and properly structured soil investigation is therefore an essential part of any civil engineering or building project (Association of Geotechnical and Geoenvironmental Specialists, Specialists, 2004).
4.1.1. Soil Investigation Layout
Total number of bore holes proposed = 5 Mackintosh probe = 13 Estimated cost = (RM 3447 x 5) + (RM139 x 13) + (RM794 x 13) = RM 19, 836 The soil investigation layout is represented in Figure 4.1 bellow.
Figure 4.1: Soil investigation layout.
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4.1.2. Soil Strata Strata of Proposed Proposed Site in General
Based on the soil investigation report, the following is the data represented in Figure 4.2 of the soil strata:
Thickness, m
Strata Description
Depth, m
SPT, N
1.5
2
3
7
4.5
1
6
0
7.5
7
9
0
10.5
4
12
1
13.5
7
15
9
16.5
14
18
16
18.6
28
20
40
21.6
50
24
50
28
50
Clay with sand 2.40
Very soft soil Sand with gravel 5.50
Loose soil Silt with sand
t s e
8.60 i t a r t e
Very soft soil Clay with silt
13.00
e
Loose soil Ground water table is found here. Sand with gravel
r a a t S : t i s e l i
17.40
Loose to medium dense soil Sand with clay 18.60
S
Medium dense soil Bed rock 21.50
Strong soil
Figure 4.2: Soil strata of proposed site 4.1.3. Risk Assessment of Underneath Soil
In determining the classification of the soil type, in this case, where the site has a layered geological stratum, the soil has to be classified according to the weakest soil type. The soil types classified here to be considered in design parameters are dark, dense, sandy and clayey. The permeability of soil is derived from the weight 41
percentage of fine fraction (fraction of particles smaller than 0.06 mm) in the soil sample (Neznal, 1995). The main disadvantage of the method is given by the fact that other factors influencing the permeability (soil moisture, density, porosity) are not taken into consideration. Furthermore, the analysis of one soil sample cannot describe a heterogeneous geological environment (Neznal, 1995).
Table 4.1: Permeabilit Permeabilit y and moisture content of soil t ypes (Davis & Wilson, 2010) Soil Texture Sand Silt Clay
Permeabilit y high low low
Moisture Conten t low high high
The sandy layers of the soil are regarded to be non-cohesive. They have lower density and more poorly graded resulting in loosely packed, low inter-granular friction and low friction angle. There is also high liquefaction potential that may causes loss of strength controlled by a combination of low density, degree of saturation and poor gradation. The higher permeability of sandy soil is undesirable for water containment structure. The clayey soil underneath are soft and finer. It is over cohesive with presence of water. There is a high risk of settlement for building, thus precautions have to be taken into account in designing the foundation type. However, the softness of the soil makes it easy for jack-in pile penetration for foundation. This layer also has a low low unconfined compressive strength, strengt h, making the use of jack-in piles further compressing the soft clay towards unbearable capacity.
4.2. Foundation 4.2.1. Type of Foundation
Type of foundation used for the project is deep foundation. The site contains very soft clay, very soft silt and loose sand at depth 0 to 16m. In addition, ground water table found at depth of 13m and bedrock layer found at depth of 19m. The loadings from structures will rest on bedrock (SPT=50) with 4m as socket piles. Type of deep foundation used is precast spun pile. Spun piles are chosen compare with precast square RC piles because of these reasons:
a. Better bending resistance b. Higher axial capacit capacit y c. Better manufacturing manufacturing quality 42
d. e. f. g.
Able to sustain higher driving stresses Higher Higher tensile capacit capacit y Easier to check integrit y of piles. Similar cost to RC square piles.
The spun pile will use cross fin shoe for easy penetration to bedrock layer and reduces slipping failure when reaching the bedrock layer. Since the site near high end residential areas, method of pile installation used is hydraulics jack-in.
Jacking force to penetrate the spun piles is 3800kN. Hydraulics jack-in produce lower noise, vibration and pollution compare with hammer method and bored method. It is also average in cost for both methods. Hydraulics jack-in can achieve 6 piles installation per day which is high productivity compare with common used bored piles.
4.2.2. Design of Foundation
Pile section used for chosen spun pile is 500mm diameter with F cu equivalent with 45N/mm² and 10T9 reinforcement. Bearing capacity from the soil will act on surface area per length length of piles and base base of piles. piles. Calculations of soil bearing capacity capacity as follow: For Skin Friction, F s Fs = k x SPT Where k = 2N/mm² Skin Resistance, Q s Qs = Fs x As Where As is the pile surface area For Base Resistance; Using Meyerhof method Base friction, Fb Fb = (40NSPT) Lb /B < 400NSPT Where NSPT is the average uncorrected blows count within 10B above and the 4B below the pile base. Lb is the depth of penetration of pile tip into the bedrock layer. Ultimate Base Resistance, Q b Qb = Fb x Ab Where Ab is area of pile's base Allowable Pile Load, Qall Qall = (Qs + Qb) / FS Where Factor of Safety, F S = 2.5 Structural Capacit Capacit y of Pile, Q st Qst = 0.25 f cu cu x A 43
Detail calculations for soil bearing capacity as in Appendix 3.1: Soil bearing capacity in the folder named Substructure design on the attached CD. 4.2.3. Piling Layout
Summary of piles groups as shown in table 4.1 below:
Table 4.2: piles groups Piles Group
Quantity
Piles Group
Quantity
Piles Group
Quantity
1 Pile
48
3 Piles
10
5 Piles
4
2 Piles
29
4 Piles
12
6 Piles
7
Number of piles per column =
Unfactored load at column Allowable pile load
Where allowable pile load calculated = 1163kN Calculation of piles per column as in Appendix 3.2: Number of piles per columns in the folder named Substructure design on the attached CD. Piling layout for spun pile foundation as Figure 4.3 below:
Figure 4.3: Piling layout
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Spun pile details
Figure 4.4: Spun pile detailing
Figure 4.5: Cross pin pile shoe detailing 4.2.4. Risk Assessment of Foundation
Pile tilt and move in soft ground ground Pile installation using hydraulics jack-in should reduce the risk of pile tilt while driven into the soil compare with hammer installation method. Verticality of piles should be checked before and after applying jacking forces. This method also prevent pile heave due to pressure relief.
Irregular bedrock profile profile Irregular bedrock layer profiles will cause piles slip sli p when hitting hard layer. Using cross pin pile shoes as recommended should encounter such risk. 45
Integrity of piles Integrity on piles group should be checked in pile group efficiently calculations. It is also will be checked by piles load test after installation on piles in group.
Settlement of piles Settlement of piles will occur due to negative skin friction from soil. P iles will allow to settle and settlement after applying load test should be monitor.
Failure due to installation installation Handling of piles from transportation to installation of piles should be checked by site engineer. Selection of pile installation contractor having more experience should be considered.
4.3. Piles Cap 4.3.1. Design of Piles Cap
Refer to Figure 4.4 for illustration. Mx, My = Moment about axis x and y 2l at least 2D of pile t at least 150mm Max pile load = TL / 4 + My/2l + Mx/2l Min pile load = TL / 4 - My/2l - Mx/2l Total axial load (TL) = P + Wpilecap Where; P = Axial load in column Wpilecap = Self weight of pile cap
Figure 4.6: Typical pile cap
46
Longitudinal Longitudinal reinforcement re inforcement (using bending method); Moment at face of the column, Mf Mf = 2 x Max pile load (l - c ₂ /2) Area of reinforcement, As As = Mf / 0.95fyz Beam shear: Shear at critical section, V V = 2 x Max pile load Stress at critical section, v v = V/Bd < 0.8 √fcu Enhanced resistance = 2dvc/av Where vc = Design concrete sheer stress (Table 3.8:BS8110) and av = l/2 Punching; Stress at column perimeter = P / (2d)(c1+c2) ( 2d)(c1+c2) < 0.8 √fcu Stress at critical perimeter = P / (4d)(2l-B) < 0.8 √fcu Detail design of all pile cap types are in Appendix 3.3: Pile cap calculation in the folder named Substructure design on the attached CD.
4.3.2. Pile Cap Details
Figure 4.7: Single pile cap detailing
47
Figure 4.8: Double piles cap detailing
Figure 4.9: Three piles cap detailing
Figure 4.10: Four piles cap detailing
48
Figure 4.11: Five piles cap detailing
Figure 4.12: Six piles cap detailing det ailing 4.3.3. Assessment of Pile Cap
Shear failure and punching failure in pile cap Shear and punching failure should be checked and provide sufficient reinforcement bars.
Eccentric loads loads from axial column column Columns should be checked for verticality during construction. A very small angle change in verticality at level 1 columns will have greater affect to top most columns.
Pressure from from soil to bottom of pile cap cap Formwork installation for pile cap should have 50mm clearance from soil surface. Installation of polystyrene should be considered as gap between soil and formwork.
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4.4. Ground Slabs 4.4.1. Typical design for ground slabs
Design using Horizontal Structural Elements (RC Slab SAFE Modeling), slab properties as follows:
Slab Properties: 275mm thickness Beam Properties: Non Wall Supports: RC walls thickness 200mm
General Properties; Modulus of elasticity: 27 kN/mm² Poisson ratio: 0.2 RC Unit weight: 24 kN/m³ Concrete cover: 40 mm Concrete strength: 35 N/mm² Reinforcing yield stress: 460 N/mm ² Loading Schedule: Dead load: 24 kN/m³ (Self weight of RC slabs, columns and beams) Live load: 3.0 kN/m² (BS 6399: Part 1 - Normal functions) Superimposed dead load (SDL): 1.0 kN/m² (Brick wall partitions + screed/finishes) Special case load (SDL): 30 kN/m² (TNB substation and ground tank) and 7.5 kN/m kN/ m ² (M&E - Assumptions w/o specifications) Slab Reinforcement Bars: Consider per meter strip using BS 8110; Minimum Reinforcement 0.13% bh = 0.13 % x 1000mm x 300 mm (max. slab thickness) = 390.0 mm² Provide T12 @ 200 for basic rebar = 565.0 mm²
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CHAPTER 5 MATERIALS QUANTITIES AND ECONOMICS
5.1. Concrete Price and and Calculations Based on the report produced by Construction Industry Development Board ( January January and February Edition), the rates and prices of materials are obtained. The price of concrete for slab, beam and columns are shown in Tables 5.1 below. For more details refer to the folder name Materials quantities and economics in the attached CD.
Table 5.1: Rate of ready mix concrete
5.1.1. Calculation for Slab ’s Concrete Costing
Calculation for slab costing is summarised in Table 5.2 bellow. Table 5.2: Calculation for slab’s concrete costing
51
5.1.2. Calculation for Beam ’s Concrete Costing
Calculation for beam costing is summarised in Table 5.3 bellow. Table 5.3: Calculation for beam’s concrete costing
5.1.3. Calculation for Column’s Concrete Costing
Calculation for column costing is summarised in Table 5.4 bellow. Table 5.4: Calculation for column ’s concrete costing
52
Table 5.4: Calculation for column ’s concrete costing (continued)
5.1.4. Calculation for Reinforced Concrete Staircases Staircases ’s Concrete Coasting
Calculation for staircases costing is summarised in Table 5.5 bellow. Table 5.5: Calculation for staircases ’ concrete costing
5.1.5. Calculation for Reinforced Concrete Concrete Sheer Sheer Wall’s Concrete Coasting
Calculation for sheer wall costing is summarised in Table 5.6 bellow. Table 5.6: Calculation for sheer wall ’s concrete costing
53
5.2. Steel Price and Calculations The calculation for the price of steel for slab, beam and columns are shown in the tables below.
5.2.1. Calculation for RC Slab ’sSt eel Coasting
Calculation for RC slab’s st eel costing is summarised in Table 5.7 bellow. Table 5.7: Calculation for RC slab’s steel costing
5.2.2. Calculation for Reinforced Concrete Beam’sS teel Coasting
Calculation for reinforced concrete bea m’s steel costing is summarised in Table 5.8 bellow. Table 5.8: Calculation for reinforced r einforced concrete beam’s st eel costing
5.2.3. Calculation for Universal Beam Coasting
Calculation for universal beam coasting is summarised in Table 5.9 bellow.
54
Table 5.9: Calculation for Universal Beam Coasting
Level
Number of Beam
Beam Size
Cross Sectional Area
Average Beam Length
Rate
(m )
(m)
(RM/m)
0.0129
11.4
353.68
2
3
2
533 x 210 x 101 UB
Price of UB
RM12,095.86
5.2.4. Calculation for RC Column’s Steel Coasting (Main Rebar)
Calculation for RC column’s steel coasting is summarised in Table 5.10 bellow. Table 5.10: Calculation for RC column ’s steel coasting (Main rebar) Column height (m)
Column size
Top Roof
3
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
8
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
7
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
6
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
5
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
4
4
3
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Level
Num. of Column
Main Rebar
Length of rebar
(m) 47 6 0 0 0 37 16 0 0 0 29 23 1 0 0 26 23 4 0 0 22 17 15 0 0 30 22 18 1 0 29 32 16 4 0
4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32
55
564 216 0 0 0 592 768 0 0 0 464 1104 48 0 0 416 1104 192 0 0 352 816 720 0 0 480 1056 864 64 0 464 1536 768 256 0
Rate (RM/m) 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91 14.91 9.10 14.91 14.91 14.91
Price of Main Rebar
RM8,409.24 RM1,965.60 RM0.00 RM0.00 RM0.00 RM8,826.72 RM6,988.80 RM0.00 RM0.00 RM0.00 RM6,918.24 RM10,046.40 RM715.68 RM0.00 RM0.00 RM6,202.56 RM10,046.40 RM2,862.72 RM0.00 RM0.00 RM5,248.32 RM7,425.60 RM10,735.20 RM0.00 RM0.00 RM7,156.80 RM9,609.60 RM12,882.24 RM954.24 RM0.00 RM6,918.24 RM13,977.60 RM11,450.88 RM3,816.96 RM0.00
2
Column height (m) 4.2
1
5.2
Total
36.4
Level
Column size 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Num. of Column
44 34 12 11 1 36 33 16 13 4 622
Main Rebar 4T32 12T25 12T32 16T32 32T32 4T32 12T25 12T32 16T32 32T32
Length of rebar
(m) 739.2 1713.6 604.8 739.2 134.4 748.8 2059.2 998.4 1081.6 665.6
Rate (RM/m)
Price of Main Rebar
14.91 9.10 14.91 14.91 14.91
RM11,021.47 RM15,593.76 RM9,017.57 RM11,021.47 RM2,003.90
14.91 9.10 14.91 14.91 14.91
RM11,164.61 RM18,738.72 RM14,886.14 RM16,126.66 RM9,924.10
RM272,656.44
5.2.5. Calculation for RC Column’sSt eel Coasting (Links)
Calculation for RC column’s steel coasting is summarised in Table 5.11 bellow. Table 5.11: Calculation for RC column ’s steel coasting (Links) Level
Column height (meter) 3
Top Roof
Column size
Num. of Column
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
47 6 0 0 0 37 16 0 0 0 29 23 1 0 0 26 23 4 0 0 22 17 15 0 0 30 22 18 1 0
8
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
7
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
6
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
5
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
4
4
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Links R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300
56
Length of links (meter)
351.56 64.68 0 0 0 377.4 235.2 0 0 0 295.8 338.1 19.2 0 0 265.2 338.1 76.8 0 0 224.4 249.9 288 0 0 306 323.4 345.6 25.2 0
Rate (RM/m)
Price of Links
1.60 1.60 1.60 1.60 1.60
RM562.50 RM103.49 RM0.00 RM0.00 RM0.00 RM603.84 RM376.32 RM0.00 RM0.00 RM0.00 RM473.28 RM540.96 RM30.72 RM0.00 RM0.00 RM424.32 RM540.96 RM122.88 RM0.00 RM0.00 RM359.04 RM399.84 RM460.80 RM0.00 RM0.00 RM489.60 RM517.44 RM552.96 RM40.32 RM0.00
1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60
Column size
3
Column height 4
2
4.2
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
1
5.2
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Total
36.4
Level
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Num. of Column 29 32 16 4 0 44 34 12 11 1 36 33 16 13 4 622
Links R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300 R10-300
Length of links 295.8 470.4 307.2 100.8 0 448.8 499.8 230.4 277.2 28.2 465.12 614.46 389.12 414.96 142.88
Rate 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60 1.60
Price of Links RM473.28 RM752.64 RM491.52 RM161.28 RM0.00 RM718.08 RM799.68 RM368.64 RM443.52 RM45.12 RM744.19 RM983.14 RM622.59 RM663.94 RM228.61 RM14,095.49
5.2.6. Calculation for RC Column’sSt eel Coasting (Hooks)
Calculation for RC column’s steel coasting is summarised in Table 5.12 bellow. Table 5.12: Calculation for RC column ’s steel coasting (Hooks) Level
Column height (meter) 3
Top Roof
8
4
7
4
6
4
5
4
4
4
Column size 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550
x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x
250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550 250 325 400 500 550
Num. of Column
Hooks
47 6 0 0 0 37 16 0 0 0 29 23 1 0 0 26 23 4 0 0 22 17 15 0 0 30 22 18 1 0
N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300
57
Length of hooks (meter) 0 64.68 0 0 0 0 235.2 0 0 0 0 338.1 19.2 0 0 0 338.1 76.8 0 0 0 249.9 288 0 0 0 323.4 345.6 12.6 0
Rate (RM/m) 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55
Price of Hooks RM0.00 RM100.25 RM0.00 RM0.00 RM0.00 RM0.00 RM364.56 RM0.00 RM0.00 RM0.00 RM0.00 RM524.06 RM29.76 RM0.00 RM0.00 RM0.00 RM524.06 RM119.04 RM0.00 RM0.00 RM0.00 RM387.35 RM446.40 RM0.00 RM0.00 RM0.00 RM501.27 RM535.68 RM19.53 RM0.00
3
Column height 4
2
4.2
1
5.2
Total
36.4
Level
Column size 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
Num. of Column 29 32 16 4 0 44 34 12 11 1 36 33 16 13 4 622
Hooks N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300 N/A 4T10-300 4T10-300 2T10-300 6T10-300
Length of hooks 0 470.4 307.2 50.4 0 0 499.8 230.4 138.6 42.3 0 614.46 389.12 207.48 214.32
Rate 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55
Price of Hooks RM0.00 RM729.12 RM476.16 RM78.12 RM0.00 RM0.00 RM774.69 RM357.12 RM214.83 RM65.57 RM0.00 RM952.41 RM603.14 RM321.59 RM332.20 RM8,456.89
5.2.7. Calculation for RC Column ’sSt eel Coasting (Total)
Calculation for RC column’s steel coasting is summarised in Table 5.13 bellow. Table 5.13: Calculation for RC column ’s steel coasting (Total) Level
Cost (RM)
TOP ROOF
RM11,141.08
8
RM17,160.24
7
RM19,279.10
6
RM20,842.94
5
RM25,462.55
4
RM33,259.68
3
RM39,325.80
2
RM52,445.42
1
RM76,292.03
TOTAL
RM295,208.82
5.2.8. Calculation for Staircase’sSt eel Coasting
Calculation for RC Stairca St aircase’s st eel coasting is summarised in Table 5.14 bellow. Table 5.14: Calculation for RC staircase’s steel coasting Level Top Roof 8
Main rebar
Number of units
Rate (RM/m) 1.55
Price of steel
22
Length of rebar (meter) 396
T10 T12 T10
96 22
576 396
2.23 1.55
RM1,284.48 RM613.80
T12
96
576
2.23
RM1,284.48
58
RM613.80
Level
7 6 5 4 3 2 1 Total
Main rebar
Number of units
T10 T12 T10 T12 T10 T12 T10 T12 T10 T12 T10 T12 T10 T12
22 96 22 96 22 96 22 96 22 96 22 96 22 96 1062
Length of rebar (meter) 396 576 396 576 396 576 396 576 396 576 396 576 396 576 6372
Rate (RM/m) 1.55 2.23 1.55 2.23 1.55 2.23 1.55 2.23 1.55 2.23 1.55 2.23 1.55 2.23
Price of steel RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM613.80 RM1,284.48 RM17,084.52
5.2.9. Calculation for Shear Wall’sSt eel Coasting
Calculation for shear wall’s st eel coasting is summarised in Table 5.15 bellow. Table 5.15: Calculation for shear wall’s steel coasting Shear Wall
Main Rebar / Links
Number of Units
Length (meter)
Dirty Lift
Lift 1,2 & 3
Lift 4,5 & 6
Length of rebar
Rates
(meter)
(RM/m)
Price of steel
Horizontal bars - T10
13
366
4758
1.55
RM7,374.90
Vertical bars - T12
38
132
5016
2.23
RM11,185.68
Links - R6
0.25
3003
750.75
0.56
RM420.42
Horizontal bars - T10
25
366
9150
1.55
RM14,182.50
Vertical bars - T12
38
250
9500
2.23
RM21,185.00
Links - R6
0.25
5733
1433.25
0.56
RM802.62
Horizontal bars - T10
25
366
9150
1.55
RM14,182.50
Vertical bars - T12
38
250
9500
2.23
RM21,185.00
Links - R6
0.25
5733
1433.25
0.56
RM802.62
Total
40917.25
5.3. Pile Caps Caps Price and and Calculations The calculation for the price of pile caps are shown in Table 5.16.
59
RM91,321.24
Table 5.16: Pile caps price and calculations PILE GROUP
CONCRETE (RM)
STEEL (RM)
2 piles
RM24,300.13
RM28,915.97
3 piles
RM5,996.02
RM5,700.25
4 piles
RM9,156.57
RM9,215.46
5 piles
RM10,190.83
RM14,321.06
12 piles
RM10,057.33
RM14,453.81
15 piles
RM12,800.24
RM17,848.68
TOTAL
RM72,501.12
RM90,455.23
5.4. Total Cost of Materials The summary of the cost is represented in Table 5.17 bellow.
Element Concrete (superstructure) Steel (superstructure) Concrete (pile caps) Steel (pile caps) Spun piles Total
60
Price (RM) RM1,133,693.11 RM1,133,693.11 RM 834,849.18 RM72,501.12 RM90,455.23 RM1,483,399.00 RM1,483,399.00 RM 3,614,897.64
