Project 1

Building floors

G + 6 + R

Plan dimension

B = 25m , L = 16m

Storey Height

h = 3.5m

Soil

Hard soil

Use

Residential Purpose

Safe Bearing Capacity

180 kN/m2

Maximum slab thickness

150mm

Basic data

Ly

3.125

m

Lx

5.5

m

shorter span

Thickness of supports

longer

6

m

shorter

4

m

Grade of concrete

fck

25

N/mm²

M25

Grade of steel

fy

415

N/mm²

Fe500

clear cover

25

mm

Design factors

x_umax/d

0.48

N.A. factor

Q_lim

3.44

M.R. factor

P_tmax

1.19

% r/f

Aspect ratio

Ly/Lx

0.568181818

TRUE

DESIGN SLAB AS TWO WAY SLAB

Assumptions for the depth of slab

cl 24.1, pg-39

MF

1.5

for Lx

& LL

3 KN/m²

d

141.03

mm

d_assumed

150

mm

D_assumed

180

mm

Computation of loading and B.M

S.Wt.

4.5

KN/m

else use cl 23.2.1, pg-37

F.F

0.8

KN/m

L.L

3

KN/m

Total Load

W

8.3

KN/m

Factored load

Wu

12.45

KN/m

Effective spans L_effective:

(as per cl 22.2, pg-34, IS 456-2000)

For Lx_eff

c/c between supports

9.5

m

clear span + d

5.65

m

Lx_eff

5.65

m

For Ly_eff

c/c between supports

9.125

clear span + d

3.275

L_yeff

3.275

m

Type of panel

TWO ADJACENT EDGE DISC.

Ly/Lx

5.76

α_x (Cont. edge)

0.288

INTERPOLATED VALUE:

α_x (Mid-span)

0.228

Ly/Lx

αx (Cont.edge)

αx (Mid-span)

α_y (Cont. edge)

0.047

1.2

0.06

0.045

α_y (Mid-span)

0.035

5.76

0.288

0.228

1.3

0.065

0.049

For span Lx

M_ux,mid-span

90.44

KNm

M_ux,cont.edge

114.54

KNm

for span Ly

M_uy,mid-span

13.91

KNm

M_uy,cont.edge

18.68

KNm

Required depth of slab

M_umax

114.54

KNm

d_req

182.36

mm

check d_req < d_assumed

TRUE

d_provided

150

mm

D_provided

180

mm

R/F area at bottom

In middle-strip

Direction

Ast_required in mm²

φ (mm)

S_required in mm

S_provided in mm

Ast_provided in mm²

SHORT (X)

2212.53

16

90.87

90

2234.02

LONG (Y)

264.73

16

759.49

300

670.21

Spacing required =

Edge strip R/F along continuous edge

Direction

Ast_required in mm²

φ (mm)

S_required in mm

S_provided in mm

Ast_provided in mm²

SHORT (X)

3381.25

16

59.46

50

4021.24

LONG (Y)

359.37

16

559.48

300

670.21

for HYSD bars, min R/F = 0.12% of b*D

Minimum R/F

A_stmin

216

mm²

OK

for MS bars, min R/F = 0.15% of b*D

At discontinuous edges at top

provide 50% of +ve R/F at top =

1452.11

mm²

OK

Therefore, at discontinuos edges required R/F area =

1668.11

mm²

φ

10

mm

S_required

47.06

mm c/c

S_provided

40

mm c/c

Torsional reinforcement

Torsion R/F at corner with both edge discontinuous

1675.52

mm²

provide 34- 8 mm #

Torsion R/F at corner with one edge discontinuous

837.76

mm²

provide 17- 8 mm #

Torsion R/F at corner with both edge continuous

0.00

mm²

DESIGN SUMMARY

Depth of slab, D

180

mm

Effective depth, d

150

mm

R/F along X-direction (SHORT)

A_{st,middle,bottom}

16# @ 90 mm c/c

A_{st,cont.edge,top}

16# @ 50 mm c/c

R/F along Y-direction (LONG)

A_st,middle

16# @ 300 mm c/c

A_st,cont.edge

16# @ 300 mm c/c

R/F at discont. edges on top in both directions

A_st,edge,top

10# @ 40 mm c/c

AREA OF TORSION REINFORCEMENT

At corner with both edge disc.

provide 34- 8 mm #

At corner with one edge disc.

provide 17- 8 mm #

At corner with both edge cont.

N.A