Slab Design(2)

1

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

2



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


= 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


= 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


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


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

3



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


= 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


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

InfoMile Solutions

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

A57

sachalla:

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

Infomile Solutions

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



One long edgediscontinuous



Two adjacent edgesdiscontinuous



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


Two long edgesdiscontinuous

Negative moment at -------- -------- -------- -------- -------- -------- -------- 0.045continuous edge


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


Three edgesdiscontinuous (one short edgecontinuous)

Negative moment at -------- -------- -------- -------- -------- -------- -------- 0.057continuous edge


Four edges discontinuous


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 _____


Three edges discontinuous

(one short edge discontinuous)

Continuous edge _____ _____ _____ _____ _____ _____ _____ _____ 0.45


Four edges discontinuous


Slab Design(2)

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