slab design(2)
TRANSCRIPT
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PROJECT : Rev Designed by Checked by Date Page of
DOC TITLE: 0 2/7/2001 Area
DOC. NO: Dept CIVIL
2.1 SLAB-S1& SLAB-S3:
Load calculations are done per metre width of the slab.Thickness of the slab is = 300.00 mmClear cover to main reinforcement = 30.00 mmDia meter of the reinforcement bar = 12.00 mmEffective depth of the slab is = 264.00 mmClear Span of the slab = 1.60 mEffective span of the slab is = 1.86 mMoment / Shear force due to Dead Load:Self weight of slab 1.00 x 0.30 x 25.0 = 7.50 kN/mWeight of the screed 1.00 x 0.05 x 25.0 = 1.25 kN/mTotal UDL due to dead load = 8.75 kN/m
= 3.80 kNmShear force ( wl/2) = 8.16 kNMoment / Shear force due to Live load:Liquid load (1.30-0.20-0.05 = 1.05) 1.00 x 1.05 x 10.0 = 10.50 kN/mTotal UDL due to live load = 10.50 kN/m
= 4.56 kNmShear force ( wl/2) = 9.79 kN
= 12.54 kNm= 26.91 kN
DESIGN FOR BENDING:Check for required effective depth:
= 33.58 mmProvided effective depth d = 264.00 mm
Main Reinforcement:Mu/bd2 = 0.18Reinforcement to keep Crack width less than 0.2mm:
% of steel required = 50((1-sqrt((1-(4.6xMu/(fckxbdd)))/(fy/fck)) = 0.05= 132.74 mm2= 360.00 mm2
Distribution Reinforcement:
Provide T10 at 125 C/C or T12 at 200 c/c.
DESIGN FOR SHEAR:= 26.91 kN= 0.10= 0.51
No shear reinforcement is required in slab.
CHECK FOR DEFLECTION:Check for Span to Effective depth ratio as per IS 456:2000:Effective Span of the slab = 1.86 m
= 20.00= 1.56= 1.00= 31.20= 59.74 mm= 264.00 mm
Effective depth provided is more than required, Hence safe.
These slabs are supporting in one-way like beams between B1 and PB1.
Maximum Bending moment( wl2/8 )
Maximum Bending moment( wl2/8)
Factored Design Moment (1.5xMd +1.5x Ml)Factored Design Shear Force (1.5xSFd +1.5x SFl)
Effective depth required, dr = sqrt(Mu/(0.138xfckx1000))
Since d > dr the provided efffective depth is OK
From Table B27 of Design Tables to BS 8007 By R.cheng(Design of concrete structures for retaining aqueous liquids)
Area of reinforcement required, Ast =Min. main reinforcement as per Cl.26.5.2.1 of IS 456:2000(0.12% of total cross section)Max. spacing as per 26.3.3.b of IS 456:2000: 3 times d or 300mm whichever is smallerProvide T10 at 125 c/c. or T12 at 200 c/c (AT BOTTOM)
Minimum reinforcement is provided in accordance with Cl.26.5.2., 26.3.3 of IS 456:2000&Table15 for spacingMax. spacing for dis. Reinforcement as per 26.3.3.b of IS 456:2000: 5 times d or 450mm whichever is smaller
Factored Design shear force Vu = (1.5SFd +1.5SFl))Nominal shear stress,ζv N/mm2
Concrete shear strength (From table 19 & 40.2.1 of IS 456:2000 for % steel of 0.55 & conrete M25) ζc N/mm2
As Concrete shear strength 0.5ζcmax > Design shear stress ζv
Basic Span to effective depth ratio ( from 23.2 of IS 456:2000)Modification factor due to % of tensile steel(Fig.4 of IS 456:2000)Modification factor due to % of compression steel(Fig.5 of IS 456:2000)Span to effective depth ratio to be provided, lef/dEffective depth required, dr
Effective depth provided, d
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PROJECT : Rev Designed by Checked by Date Page of
DOC TITLE: 0 2/7/2001 Area
DOC. NO: Dept CIVIL
2.3 SLAB S5 & S6:Clear dimensions of the slab = 3.5x5.15 mClear span in Short direction = 3.5 mm Clear span in long direction = 5.15 mm
= 300 mm = 264 mm= 3.76 m= 5.41 m= 1.44
Dead load:Self weight of the slab 0.3 x 1 x 25 = 7.5Weight of the screed 1.0 x 0.05 x 25 = 1.25Total UDL due to dead load = 8.75Live load:Liquid weight 1.0 x 2.15 x 10 = 21.5Total UDL due to live load = 21.5Slab is considered designed as an Interior pannelCo-efficints for Bending moments are taken from table 26 of IS 456:2000.i) Shorter direction moments:a) Positive moment at mid span
0.0395 x 8.75 x 14.2 = 4.90 kNm0.0395 x 21.5 x 14.2 = 12.03 kNm
Reinforcement to keep Crack width less than 0.2mm:
= 16.93 KNm= 25.39 KNm
= 0.36= 0.10= 271.16 mm2= 360.00 mm2
Provide T10 at 125 c/c or T12 at 200 c/c(From SP16 of IS 456:2000)b) Negative moment at continuous support
0.0515 x 8.75 x 14.0 = 6.31 kNm0.0515 x 21.5 x 14.0 = 15.50 kNm
Reinforcement to keep Crack width less than 0.2mm:
= 21.81 KNm= 33.63 KNm= 0.48= 0.14= 361.25 mm2= 360.00 mm2
Provide T10 at 125 c/c or T12 at 200 c/c
ii) Longer direction moments:a) Positive moment at mid spanPositive moment at mid span due to dead load 0.024 x 8.75 x 14.0 = 2.94 kNmPositive moment at mid span due to live load 0.024 x 21.5 x 14.0 = 7.22 kNm
Reinforcement to keep Crack width less than 0.2mm:
= 10.16 KNm= 15.25 KNm= 0.23
Thickness of slab, Df = 300mm, Thickness of the wall/beam supporting the slab Effective depth of the slab d = (300 -30-12 / 2)Effective span in shorter direction, lx
Effective span in longer direction, ly ly/lx
kN/m2
kN/m2
wd kN/m2
kN/m2
wl kN/m2
Positive moment at mid span due to dead load (3.74x3.74 =14.0)αx .w lx2
Positive moment at mid span due to live load αy.w.lx2
Reinforcement as per BS 8007:(BS Code of Practice for Design of Concrete structures for retaining aqueous liquids)
From Table B27 of Design Tables to BS 8007 By R.Cheng(Design of concrete structures for retaining aqueous liquids)Service Bending Moment (Md + Ml)Ultimate Bending Moment (1.5x(Md +Ml))
Mu/bd2
% of steel required = 50((1-sqrt((1-(4.6xMu/(fckxbd2)))/(fy/fck))Area of reinforcement required, Ast =Min. main reinforcement as per Cl.26.5.2.1 of IS 456:2000(0.12% of total cross section)Max. spacing as per 26.3.3.b of IS 456:2000: 3 times d or 300mm whichever is smaller
Negative moment at support due to dead load αx .w lx2
Negative moment at support due to live load αy .w lx2
Reinforcement as per BS 8007:(BS Code of Practice for Design of Concrete structures for retaining aqueous liquids)
From Table B27 of Design Tables to BS 8007 By R.Cheng(Design of concrete structures for retaining aqueous liquids)Service Bending Moment (Md + Ml)Ultimate Bending Moment Mu = (1.5xMd + 1.5xMl)Mu/bd²% of steel required = 50((1-sqrt((1-(4.6xMu/(fckxbd2)))/(fy/fck))Area of reinforcement required, Ast =Min. main reinforcement as per Cl.26.5.2.1 of IS 456:2000(0.12% of total cross section)Max. spacing as per 26.3.3.b of IS 456:2000: 3 times d or 300mm whichever is smaller
Reinforcement as per BS 8007:(BS Code of Practice for Design of Concrete structures for retaining aqueous liquids)
From Table B30 of Design Tables to BS 8007 By R.Cheng(Design of concrete structures for retaining aqueous liquids)Service Bending Moment (Md + Ml)Ultimate Bending Moment Mu = (1.5xMd + 1.5xMl)Mu/bd²
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PROJECT : Rev Designed by Checked by Date Page of
DOC TITLE: 0 2/7/2001 Area
DOC. NO: Dept CIVIL
= 0.06= 164.86 mm2= 360.00 mm2
Provide T10 at 125 c/c or T12 at 200 c/cb) Negative moment at continuous support
0.032 x 8.75 x 14.0 = 3.92 kNm0.032 x 21.5 x 14.0 = 9.63 kNm
Reinforcement to keep Crack width less than 0.2mm:
= 13.55 KNm= 20.33 KNm= 0.30= 0.09= 220.61 mm2= 360.00 mm2
Provide T10 at 125 c/c or T12 at 200 c/c
DESIGN FOR SHEAR ALONG SHORTER DIRECTION:= 3.76 m= 5.41= 1.44
Total Design Ultimate load per unit area (1.5x(Dead load + Live load)) = 45.38= 85.40
Ultimate Design shear force = 85.40= 0.32= 0.29= 1.55
No shear reinforcement is required in slab.
DESIGN FOR SHEAR ALONG LONGER DIRECTION:Shear check along shorter direction is done considering shear strength for minimum longitudinal reinforcement, Hence shear check along longer edge is not required.
CHECK FOR DEFLECTION:Check for Span to Effective depth ratio as per BS 8110:Effective Span of the slab = 3.76 mBasic Span to effective depth ratio ( from CL.24.1 of IS 456:2000) = 26.00Modification factor due to % of tensile steel(Fig.4 of IS 456:2000) = 1.34Modification factor due to % of compression steel(Fig.5 of IS 456:2000) = 1.00Span to effective depth ratio to be provided = 34.84Effective depth required = 108.04 mmEffective depth provided = 264.00 mmEffective depth provided is more than required, Hence safe.
% of steel required = 50((1-sqrt((1-(4.6xMu/(fckxbd2)))/(fy/fck))Area of reinforcement required, Ast =Min. main reinforcement as per Cl.26.5.2.1 of IS 456:2000(0.12% of total cross section)Max. spacing as per 26.3.3.b of IS 456:2000: 3 times d or 300mm whichever is smaller
Negative moment at support due to dead load αx .w lx2
Negative moment at support due to live load αy .w lx2
Reinforcement as per BS 8007:(BS Code of Practice for Design of Concrete structures for retaining aqueous liquids)
From Table B30 of Design Tables to BS 8007 By R.Cheng(Design of concrete structures for retaining aqueous liquids)Service Bending Moment (Md + Ml)Ultimate Bending Moment Mu = (1.5xMd + 1.5xMl)Mu/bd²% of steel required = 50((1-sqrt((1-(4.6xMu/(fckxbd2)))/(fy/fck))Area of reinforcement required, Ast =Min. main reinforcement as per Cl.26.5.2.1 of IS 456:2000(0.12% of total cross section)Max. spacing as per 26.3.3.b of IS 456:2000: 3 times d or 300mm whichever is smaller
Effective span in shorter direction, lx
Effective span in longer direction, ly ly/lx
kN/m2
Maximum Shear Force as per IS 456:2000 Vu = w lx/2Vu
Design shear stress, ζv N/mm2
Concrete shear strength (From table19 & 40.2.3.1 of IS 456:2000 for % steel of 0.13 & conrete M25) ζv N/mm2
As per Cl. 40.2.3.1 nominal shear stess shall not exceed Half the value in Table 20 ζcmax N/mm2
As Concrete shear strength ζv is more than 0.5ζcmax
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PROJECT : MODEL BLDG.
DOC TITLE : DESIGN OF SUPER STRUCTURE
DOC. NO : XXXXXXXXXXXXX
Design of Two-Way Slab SLAB TYPE - LEGEND
Grade of Concrete 25 1. Interior panels
Grade of Steel 415 2. One short edge discontinuous
Clear Cover C 30 3. One long edge discontinuous
MEMBER INFORMATION
SlabSlab TypeDirection Df Dia d
S1 1 Shorter 150 12 114 4 4.11 4.5 7.00 1.702
1 Longer 150 10 103 4 4.10 4.5 4.60 1.122
S2 Shorter
Longer
S3 Shorter
Longer
S4 Shorter
Longer
S5 Shorter
Longer
S6 Shorter
Longer
S7 Shorter
Longer
S8 Shorter
Longer
S9 Shorter
Longer
S10 Shorter
Longer
fck
fy
lox lx loy ly ly/lx
S11 Shorter
Longer
S12 Shorter
Longer
S13 Shorter
Longer
MEMBER INFORMATION
Slab Direction Dia d
S1 1 Shorter 150 12 114 4 4.11 4.5 4.61 1.122
1 Longer 150 10 103 4 4.10 4.5 4.60 1.122
S2 Shorter
Longer
S3 Shorter
Longer
S4 Shorter
Longer
S5 Shorter
Longer
S6 Shorter
Longer
S7 Shorter
Longer
S8 Shorter
Longer
S9 Shorter
Df =Thickness of slab lx =Effective span in Shorter direction
C =Clear cover to reinforcementloy =Clear span in longer direction
Dia =Diameter ly =Effective span in Longer direction
d =Effective depth of slab
lox =Clear Span in shorter direction
Slab Type Df lox lx loy ly ly/lx
Longer
S10 Shorter
Longer
S11 Shorter
Longer
S12 Shorter
Longer
S13 Shorter
Longer
Df=Thickness of slab lox =Clear Span in shorter direction
C=Clear cover to reinforcement lx =Effective span in Shorter direction
Dia=Diameter loy =Clear span in longer direction
d=Effective depth of slab ly =Effective span in Longer direction
InfoMile Solutions
MODEL BLDG.
DESIGN OF SUPER STRUCTURE
XXXXXXXXXXXXX
SLAB TYPE - LEGEND
4. Two adjacent edges discontinuous 7. Three edges discontinuous (one long edge continuous)
5. Two short edges discontinuous 8. Three edges discontinuous (one short edge continuous)
6. Two long edges discontinuous 9. Four edges discontinuous
POSITIVE BENDING MOMENT (BOTTOM REINFT.)
% steel Reinforcement
Dia
### 2.5 30 ### ### ### ### ### ### 10.00 ###
### 2.5 30 ### ### ### ### ### ### 10.00 ###
αx or αy
wd wl Md Ml
Mx or My
Mu/bd2 Ast
Sv
DESIGN FOR SHEAR
Remarks
0.500 1 10 2.057 20.57 33.94 0.298 ### ### #VALUE!
0.500 1 10 0.5 20.52 31.52 0.306 ### ### #VALUE!
αx =Co-efficient for Bending Moment along shorter span
αy =Co-efficient for Bending Moment along longer span
wd =Dead load in kN/m2
wl =Live load in kN/m2
lx/2 wd wl SFd SFl
Vu ζv
% Steel ζc (or)
ζcmax/2
αx =Co-efficient for Shear force along shorter span SFl =Shear force due to live load
αy =Co-efficient for Shear force along longer span Vu =Factored Shear force
wd =Dead load UDL in kN/m2 ζ=Design shear stress
wl =Live load UDlin kN/m2 ζc=Parmissible Shear strength of concrete
SFd =Shear force due to dead load ζcmax= Max. Shear strength of concrete
InfoMile Solutions
MODEL BLDG. Rev Designed Checked Approved Page of
DESIGN OF SUPER STRUCTURE 0 xx
XXXXXXXXXXXXX Dept Civil/Structural
SLAB TYPE - LEGEND
7. Three edges discontinuous (one long edge continuous)
8. Three edges discontinuous (one short edge continuous)
POSITIVE BENDING MOMENT (BOTTOM REINFT.) NEGATIVE BENDING MOMENT (TOP REINFT.)
% stee Reinforcement
Dia
### ### ### ### ### ### ### ### 10 ### ###
### ### ### ### ### ### ### ### 10 ### ###
αx or αy
Md Ml
Mx or My
Mu/bd2 Ast
Astp Sv A'sp
Mu=Ultimate bending moment
DESIGN FOR SHEAR CHECK FOR DEFLECTION
Remarks Bt Bc d Remarks
#VALUE! 4.114 35 1.23 1 43.05 95.563 114 Safe
#VALUE!
Md=Moment due to dead load
Ml=Moment due to live load
lx
From Chart lx/d
Provided lx/d dr
lx =Effective span of the slab
Bt =Modification factor due to % of tensile steel
Bc =Modification factor due to % of compression steel
=Parmissible Shear strength of concrete dr =Effective depth required
= Max. Shear strength of concrete
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PROJECT : MODEL BLDG.
DOC TITLE : DESIGN OF SUPERSTRUCTURE
DOC. NO : xxxxxxxxxxxxxxxxx
Design of One-Way Slab
Grade of Concrete 25
Grade of Steel 415
Clear Cover C 30
MEMBER INFORMATION DESIGN FOR BENDING MOMENT
Slab C ∅ d l
S1 & S3 300 30 12 264 1.6 1.86 8.75 3.80 10.5 4.56
fck
fy
Df lef wd Md wl Ml
Df=Thickness of slab wd =Dead load UDL
C=Clear cover Md =Moment due to dead load
∅=Diameter wl =Live load UDL
d =Effective depth of slab Ml =Moment due to live load
l =Clear span of the slab Mu =Factored design moment
lef =Effective span of the slab b =width of slab=1000mm
Infomile Solutions
MODEL BLDG.
DESIGN OF SUPERSTRUCTURE
xxxxxxxxxxxxxxxxx Department
DESIGN FOR BENDING MOMENT DESIGN FOR SHEAR
%steel ζ
12.54 0.18 0.12 T12 at 200 c/c ( BOT) T12 at 200 c/c 8.16 9.79 26.91 0.10
Mu Mu/bd²Main
ReinforcementDistribution
Reinforcement SFd SFl Vu
SFd=Shear force due to dead load
=Moment due to dead load SFl=Shear force due to live load
Vu=Factored design Shear force
=Moment due to live load ζ= Nominal shear stress
=Factored design moment ζc= Permissible Concrete shear strength
=width of slab=1000mm ζcmax = Max. shear stength of concrete
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Rev Designed Checked Approved Page of
0 XX XX XX 3 3
Department Civil/Structural
DESIGN FOR SHEAR CHECK FOR DEFLECTION
%steel Remarks Bt Bc
0.12 ### ### 1.86 20 1.56 1 31.2 59.74 264 Safe
ζc or ζc,max lef
From Chart bw/d Lef/dr dr dp
Remarks
=Shear force due to dead load lef/d=Basic span to effective depth ratio
=Shear force due to live load Bt=Modification factor due to % of tensile steel
=Factored design Shear force Bc=Modification factor due to % of compression steel
= Nominal shear stress dr=Effective depth required
= Permissible Concrete shear strength dp=Effective depth provided
= Max. shear stength of concrete lef=Effective span of the slab
Table 26 Bending moment coefficients for rectangular panels supported on four sides with provision for torsion at corners
Type of panel and moments
considered1.0 1.1 1.2 1.3 1.4 1.5 1.75 2.00
Interior panels1.441
Negative moment at 0.032 0.037 0.043 0.047 0.051 0.053 0.060 0.065 0.032 0.05182continuous edge
Positive moment at mid-sp 0.024 0.028 0.032 0.036 0.039 0.041 0.045 0.049 0.024 0.03982
One short edgediscontinuous
Negative moment at 0.037 0.043 0.048 0.051 0.055 0.057 0.064 0.068 0.037 0.05582continuous edge
Positive moment at mid-sp 0.028 0.032 0.036 0.039 0.041 0.044 0.048 0.052 0.028 0.04223
One long edgediscontinuous
Negative moment at 0.037 0.044 0.052 0.057 0.063 0.067 0.077 0.085 0.037 0.06464continuous edge
Positive moment at mid-sp 0.028 0.033 0.039 0.044 0.047 0.051 0.059 0.065 0.028 0.04864
Two adjacent edgesdiscontinuous
Negative moment at 0.047 0.053 0.060 0.065 0.071 0.075 0.084 0.091 0.047 0.07264continuous edge
Positive moment at mid-sp 0.035 0.040 0.045 0.049 0.053 0.056 0.063 0.069 0.035 0.05423
Two short edgesdiscontinuous
Negative moment at 0.045 0.049 0.052 0.056 0.059 0.060 0.065 0.069 -------- 0.05941continuous edge
Positive moment at mid-sp 0.035 0.037 0.040 0.043 0.044 0.045 0.049 0.052 0.035 0.04441
Two long edgesdiscontinuous
Negative moment at -------- -------- -------- -------- -------- -------- -------- 0.045continuous edge
Positive moment at mid-sp 0.035 0.043 0.051 0.057 0.063 0.068 0.080 0.088 0.035 0.06505
Three edgesdiscontinuous (one long edgecontinuous)
Negative moment at 0.057 0.064 0.071 0.076 0.080 0.084 0.091 0.097 -------- 0.08164continuous edge
Positive moment at mid-sp 0.043 0.048 0.053 0.057 0.060 0.064 0.069 0.073 0.043 0.06164
Three edgesdiscontinuous (one short edgecontinuous)
Negative moment at -------- -------- -------- -------- -------- -------- -------- 0.057continuous edge
Positive moment at mid-sp 0.043 0.051 0.059 0.065 0.071 0.076 0.087 0.096 0.043 0.07305
Four edges discontinuous
Positive moment at mid-sp 0.056 0.064 0.072 0.079 0.085 0.089 0.1 0.107 0.056 0.08664
Short span coefficients,αxLong span coefficients, αy for all values of ly/lx
Values of ly/lx
Table 3.15 Shear force coefficient for uniformly loaded rectangular panel supported on four sides with provision for torsion at corners
Type of panel and location βvx for values of ly/lx βvy
1.0 1.1 1.2 1.3 1.4 1.5 1.75 2.00Four edges continuous
Continuous edge 0.33 0.36 0.39 0.41 0.43 0.45 0.48 0.5 0.33
One short edge discontinuous
Continuous edge 0.36 0.39 0.42 0.44 0.45 0.47 0.5 0.52 0.36
Discontinuous edge _____ _____ _____ _____ _____ _____ _____ _____ 0.24
One long edge discontinuous
Continuous edge 0.36 0.4 0.44 0.47 0.49 0.51 0.55 0.59 0.36
Discontinuous edge 0.24 0.27 0.29 0.31 0.32 0.34 0.36 0.38 _____
Two adjacent edges discontinuous
Continuous edge 0.4 0.44 0.47 0.5 0.52 0.54 0.57 0.6 0.4
Discontinuous edge 0.26 0.29 0.31 0.33 0.34 0.35 0.38 0.4 0.26
Two short edges discontinuous
Continuous edge 0.4 0.43 0.45 0.47 0.48 0.49 0.52 0.54 _____
Discontinuous edge _____ _____ _____ _____ _____ _____ _____ _____ 0.26
Two long edges discontinuous
Continuous edge _____ _____ _____ _____ _____ _____ _____ _____ 0.4
Discontinuous edge 0.26 0.3 0.33 0.36 0.38 0.4 0.44 0.47 _____
Three edges discontinuous
(one long edge discontinuous)
Continuous edge 0.45 0.48 0.51 0.53 0.55 0.57 0.6 0.63 _____
Discontinuous edge 0.3 0.32 0.34 0.35 0.36 0.37 0.39 0.41 0.29
Three edges discontinuous
(one short edge discontinuous)
Continuous edge _____ _____ _____ _____ _____ _____ _____ _____ 0.45
Discontinuous edge 0.29 0.33 0.36 0.38 0.4 0.42 0.45 0.48 0.3
Four edges discontinuous
Discontinuous edge 0.33 0.36 0.39 0.41 0.43 0.45 0.48 0.5 0.33