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DESIGN OF SLAB

Toilet no.2 4.5x3 m

.DEPTH

Assuming 300 mm wall thickness

Lx =3.0 + 0.3 = 3.3 m

Ly = 4.5 + 0.3 = 4.8m

Assume Pt = 0.2%

Modification factor = 1.63

Effective depth d = Lx/(26x 1.63) = 4800/(26 x 1.63) = 113mm

Take d = 150 mm

Overall depth = 150 + 30 = 180 mm

Ly = 4.5 + d = 4.5 + 1.5 = 4.65m

Lx = 3.0 + d = 3.0 + .15 = 3.15 m

Loads : for 1 m wide strip

Dead load = 25bd = 25 x 1 x 0.18 = 4.5 kN/m

Live load = 2.5 kN/m2 x 1 = 2.5 kN/m

Total working load = 7.0 kN/m

Factored load w = 1.5 x 7.0 = 10.5 kN/m

. Design Moments

Ly/Lx =4.65/ 3.15 =1.48

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BM coefficients (Table 26;IS 456)

Ax =0.075 ay =0.047

Ax+ =0.056 ay+ =0.035Mx = 0.075x 10.5 x 3.152=708 kNm

Mx+ = 0.056x 10.5x3. 152 =5.8 kNm

My- =0.047 x10.5x 3. 152

4.8 kNmMy- = 0.035x10.5x3.152=3.6kNm

.Minimum depth required

Mmax.=7.8 kNmd=[M/(0.138fck b)] =53.2mmo.k

.Area of steel

Ast=-0.5fck 1-(4.6M/fckbd2)bdAstx- =150mm2

Astx-+=112mm2

Astx- =102mm2

Astx+ =75mm

2

Ast min =0.12x180x1000/100=216 mm2

Take care,

Astx+ =216 mm2

Astx- =216 mm2

Astx+ =216 mm2

Astx- =216 mm2

48

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Spacing c/c= area of one bar X h

Steel area

For 12 mm bar

Sx.=sx+ = sy- = sy +300 mm

Check for shear

Kn

V = wlx/2 =24.57kN

T= V/bd = 0.16 N/mm

Pt=Astmax./bd=0.19% (Table 19 ; IS 456)

r=0.32 N/mm2>r ok

Distrbutin steel

Astd =.12/1000x10000x180

=216mm2

Promide 8mm dia bars@ 230mm c/c

Torsion steel

At corners where slab is discontinuous over both the edges

At =3/4x216=162mm2

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DESIGN OF SLAB

Toilet no.2 4.5x3 m

.DEPTH

Assuming 300 mm wall thickness

Lx =3.0 + 0.3 = 3.3 m

Ly = 4.5 + 0.3 = 4.8m

Assume Pt = 0.2%

Modification factor = 1.63

Effective depth d = Lx/(26x 1.63) = 4800/(26 x 1.63) = 113mm

Take d = 150 mm

Overall depth = 150 + 30 = 180 mm

Ly = 4.5 + d = 4.5 + 1.5 = 4.65m

Lx = 3.0 + d = 3.0 + .15 = 3.15 m

Loads : for 1 m wide strip

Dead load = 25bd = 25 x 1 x 0.18 = 4.5 kN/m

Live load = 2.5 kN/m2 x 1 = 2.5 kN/m

Total working load = 7.0 kN/m

Factored load w = 1.5 x 7.0 = 10.5 kN/m

. Design Moments

Ly/Lx =4.65/ 3.15 =1.48

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BM coefficients (Table 26;IS 456)

ax- =0.075 ay =0.047

ax+ =0.056 ay+ =0.035

Mx- = 0.075x 10.5 x 3.152

=7.8 kNmMx+ = 0.056x 10.5x3. 152 =5.8 kNm

My- =0.047 x10.5x 3. 152 4.8 kNm

My- = 0.035x10.5x3.152=3.6kNm.Minimum depth required

Mmax.=7.8 kNm

d=[M/(0.138fck b)] =53.2mmo.k

.Area of steel

Ast=-0.5fck 1-(4.6M/fckbd2)bd

Astx- =150mm2

Astx-+=112mm

2

Astx- =102mm2

Astx+ =75mm2

Ast min =0.12x180x1000/100=216 mm2

Take care,

Astx+ =216 mm2

Astx- =216 mm2

Astx+ =216 mm2

Astx- =216 mm2

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Spacing c/c= area of one bar X h

Steel area

For 12 mm bar

Sx.=sx+ = sy- = sy +300 mm

Check for shear

Kn

V = wlx/2 =24.57kN

T= V/bd = 0.16 N/mm

Pt=Astmax./bd=0.19% (Table 19 ; IS 456)

r=0.32 N/mm2>r ok

Distrbutin steel

Astd =.12/1000x10000x180

=216mm2

Promide 8mm dia bars@ 230mm c/c

Torsion steel

At corners where slab is discontinuous over both the edges

At =3/4x216=162mm2

52

DESIGN OF SLAB

STAFF ROOM 4.5X6.0 m

.Depth

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Aussuming 300 mm wall thickness

Lx =4.5+03 = 4.8 m

Ly = 6.0 + 0.3 = 6.3m

Assume Pt = 0.2%

Modification factor = 1.63 (Clause 23.2 ; Fig. 4 ;IS 456)

Effective depth d = Lx/(26x 1.63) = 4800/(26 x 1.63) = 113mm

Take d = 150 mm

Overall depth = 150 + 30 = 180 mm

Lx = 4.5 + d = 4.5 + .15 = 4.65m

Ly = 6.0 + d = 6.0 + .15 = 6.15 m

Loads : for 1 m wide strip

Dead load = 25bd = 25 x 1 x 0.18 = 4.5 kN/m

Live load = 2.5 kN/m2 x 1 = 2.5 kN/m

Total working load = 7.0 kN/m

Factored load w = 1.5 x 7.0 = 10.5 kN/m

. Design Moments

Lx/Ly =6.15/ 4.65 =1.3

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.Minimum depth required

Mmax.=11.58 kNmd=[M/(0.138fck b)] =64.8mm o.k

.Area of steelAst=-0.5fck 1-(4.6M/fckbd2)bd

Astx- =223.6mm2

Astx-+=169.7mm2

Astx- =160.8mm2

Astx+ =116mm2

Ast min =0.12x180x1000/100=216 mm2

Take care,

Astx+ =216 mm2

Asty- =216 mm2

Asty+ = 216 mm2

Spacing c/c = area of one bar x b

Steel area

54

For 12 mm bar

Sx- = Sx+ = Sy+ =300mm

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Check for shear

V = wLx /2 =24.57kN

t= V/bd = 0.16 N/mm2

Pt=Astmax./bd=0.19% (Table 19 ; IS 456)

r` = 0.32 N/mm2>t o.k

Distributin steel

Astd =.12/1000x10000x180

=216mm2

Provide 8 mm@ 230 mm c/c

Torsion steel

At corners where slab is discontinuous over both the edges

At =3/4x216=162mm2

55

DESIGN OF SLAB

. Depth

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Aussuming 300 mm wall thickness

Lx =3.6+0.3 =3.9 m

Ly = 4.5 + 0.3 = 4.8 m

Assume Pt = 0.2%

Modification factor = 1.63 (Clause 23.2 ; Fig. 4 ;IS 456)

Effective depth d = Lx/(26x 1.63) = 4800/(26 x 1.63) = 113mm

Take d = 150 mm

Overall depth = 150 + 30 = 180 mm

Ly =4.5 + d = 4.5 + .15 = 4.65m

Lx= 3.0+ d = 3.6 + .15 = 3.75 m

Loads : for 1 m wide strip

Dead load = 25bd = 25 x 1 x 0.18 = 4.5 kN/m

Live load = 2.5 kN/m2 x 1 = 2.5 kN/m

Total working load = 7.0 kN/m

Factored load w = 1.5 x 7.0 = 10.5 kN/m

. Design Moments

Ly/Lx = 4.65/ 3.75 = 1.2,2.0

It`s a case of 2-way slab with two adjacent edges discontinuous.

56BM coefficients (Table 26;IS 456)

ax- =0.075 ay =0.047

ax+ =0.056 ay+ =0.035Mx- = 0.075x 10.5 x 3.152=7.8 kNm

Mx+ = 0.056x 10.5x3. 152 =5.8 kNm

My- =0.047 x10.5x 3. 152 4.8 kNm

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My- = 0.035x10.5x3.152=3.6kNm

.Minimum depth required

Mmax.=7.8 kNmd=[M/(0.138fck b)] =53.2mmo.k

.Area of steelAst=-0.5fck 1-(4.6M/fckbd2)bd

Astx- =150mm2

Astx-+=112mm2

Astx- =102mm2

Astx+ =75mm2

Ast min =0.12x180x1000/100=216 mm2

Take care,

Astx+ =216 mm

2

Astx- =216 mm2

Astx+ =216 mm2

Astx- =216 mm2

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