DESIGN OF ONE WAY CONTINUOUS SLAB

1 Input data:

short span =

Slab thickness =
Assume slab thickness =

Self weight of the slab =

Filling load in toilet slab =
Finishes load =
Machine/Equipment load =
Water proof course load =
water tank load =
Live load =
Edge condition =
Total load intensity on slab =
Take w =
fck =
fy =
Clear Cover =
Diameter of the Bar Dia main =
Dia sec =
Minimum Steel =
D =
d main =
d sec =
ly/lx =

3.00 m

2 Calculations:
 Panel type short span Positive (span moments)

2.00 3.00 Negative (supports moments)

Mx Mx +ve
Moment = 7.54 kN-m
Factored Mu = 11.31 kN-m
d = 126.00 mm
Mu/bd 2
= 0.71 N/mm2
pt = 0.170 %
Ast reqd = 214.10 mm2
Diameter of bar = 8 mm
Spacing required = 235 mm c/c
Spacing provided = 100 mm c/c
Ast provided = 502.7 mm2

3 Check for Deflection:

span/depth = 23.81 Permissible value

Area of steel provided =

Provided pt =
fs =
Modification factor =

4 Check for shear stress:

Factored Vu = 17.55 kN
Shear stress = 0.139 N/mm2
τcmax = 3.1 N/mm2
Provided pt = 0.399 %
τc = 0.437 N/mm2
modification factor k = 1.3
τcmodified = 0.57 N/mm2

5 Distribution Reinforcement:
 Ast reqd = 180 mm2
Diameter of bar = 8 mm
Spacing required = 279 mm c/c
Spacing provided = 200 mm c/c

Bending moment coe

Span moments
Type of loadNear middle of end span
At middle of interior span
Dead loads 0.08 0.06
Live loads 0.10 0.08

Shear Force coeffi

Type of load At End support At support next to

Outer side
Dead loads 0.40 0.60
Live loads 0.45 0.60
ONTINUOUS SLAB

Maximum shear stress tc.max in

3.00 m
(IS : 456-2000)
Grade of concrete
107 mm M-15
150 mm (say) M-20

3.75 kN/m2 M-25

0.00 kN/m2 M-30
1.50 kN/m2 M-35
0.00 kN/m2 M-40
0.00 kN/m 2

0.00 kN/m2
Depth of
4.00 kN/m2 slab
2.00 0
9.25 kN/m2 150
9.25 kN/m2 175
25 N/mm2 200
500 N/mm2 225
20 mm 250
8 mm Ok 275
8 mm 300
0.12 % 3000
150.00 mm
126.00 mm
118.00 mm
0.00

Design shear strength of concrete, τc

100As
M-20
bd
0 0.28
0.15 0.28
0.25 0.36
0.50 0.48
0.75 0.56
1.00 0.62
 ve (span moments) 7.54 kN-m 1.25 0.67
1.50 0.72
e (supports moments) 8.73 kN-m
1.75 0.75
+ve Mx -ve 2.00 0.79
kN-m 8.73 kN-m 2.25 0.81
kN-m 13.09 kN-m 2.50 0.82
mm 118.00 mm 2.75 0.82
N/mm 2
0.94 N/mm 2
3 0.82
% 0.226 % 100 0.82
mm2 267.13 mm2
mm 8 mm
mm c/c 188 mm c/c
mm c/c 180 mm c/c (say)
mm2 279.3 mm2

missible value = 69.65

502.65
0.399 %
123.52
2.679 from IS 456
Safe

Safe

Safe
 Bending moment coefficients
s Support moments
At middle of interior spanAt support next to end supportAt other interior supports
0.06 -0.10 -0.08
0.08 -0.11 -0.11

Shear Force coefficients

At support next to the end support At all other interior supports

Outer side Inner side

0.60 0.55 0.50

0.60 0.60 0.60
 fck = 20 & fy 500 N/mm2
Mu/bd2
Maximum shear stress tc.max in concrete
0.00
(IS : 456-2000)
Grade of concrete Fck tc.max 0.30
M-15 15 2.5 0.35
M-20 20 2.8 0.40

M-25 25 3.1 0.45

M-30 30 3.5 0.50
M-35 35 3.7 0.55
M-40 40 4 0.60
0.65
0.70
Multiplying
factor k
0.75
1.3 0.80
1.3 0.85
1.25 0.90
1.2 0.95
1.15 1.00
1.1 1.05
1.05 1.10
1 1.15
1 1.20
1.25
1.30
1.35
1.40
1.45
n shear strength of concrete, τc N/mm (IS : 456-2000)
2
1.50
100As 100As 1.55
M-25 M-30
bd bd 1.60
0 0.29 0 0.29 1.65
0.15 0.29 0.15 0.29 1.70
0.25 0.36 0.25 0.37 1.75
0.50 0.49 0.50 0.50 1.80
0.75 0.57 0.75 0.59 1.85
1.00 0.64 1.00 0.66 1.90
1.25 0.70 1.25 0.71 1.95
1.50 0.74 1.50 0.76 2.00
1.75 0.78 1.75 0.80 2.02
2.00 0.82 2.00 0.84 2.04
2.25 0.85 2.25 0.88 2.06
2.50 0.88 2.50 0.91 2.08
2.75 0.90 2.75 0.94 2.10
3 0.92 3 0.96 2.12
100 0.92 100 0.96 2.14
2.16
2.18
2.20
2.22
2.24
2.26
2.28
2.30
2.32
2.34
2.36
2.38
2.40
2.42
2.44
2.46
2.48
2.50
2.52
2.54
2.56
2.58
2.60
2.62
2.64
2.66
Max 2.66
20 & fy 500 N/mm2 fck = 25 & fy 500 N/mm2 fck = 30 & fy 500 N/mm2
Pt Mu/bd2 Pt Mu/bd2 Pt

0.070 0 0.07 0 0.07

0.070 0.3 0.07 0.3 0.07

0.082 0.35 0.082 0.35 0.082
0.094 0.4 0.094 0.4 0.093

0.106 0.45 0.106 0.45 0.105

0.119 0.5 0.118 0.5 0.117
0.131 0.55 0.13 0.55 0.129
0.143 0.6 0.142 0.6 0.141
0.156 0.65 0.154 0.65 0.153
0.168 0.7 0.167 0.7 0.166
0.181 0.75 0.179 0.75 0.178
0.193 0.8 0.191 0.8 0.19
0.206 0.85 0.204 0.85 0.202
0.219 0.9 0.216 0.9 0.215
0.232 0.95 0.229 0.95 0.227
0.245 1 0.242 1 0.24
0.258 1.05 0.255 1.05 0.252
0.272 1.1 0.267 1.1 0.265
0.285 1.15 0.28 1.15 0.277
0.298 1.2 0.293 1.2 0.29
0.312 1.25 0.306 1.25 0.303
0.326 1.3 0.32 1.3 0.316
0.339 1.35 0.333 1.35 0.329
0.353 1.4 0.346 1.4 0.342
0.367 1.45 0.359 1.45 0.355
0.382 1.5 0.373 1.5 0.368
0.396 1.55 0.387 1.55 0.381
0.410 1.6 0.4 1.6 0.394
0.425 1.65 0.414 1.65 0.407
0.440 1.7 0.428 1.7 0.421
0.454 1.75 0.442 1.75 0.434
0.469 1.8 0.456 1.8 0.448
0.484 1.85 0.47 1.85 0.461
0.500 1.9 0.484 1.9 0.475
0.515 1.95 0.498 1.95 0.488
0.531 2 0.513 2 0.502
0.537 2.05 0.527 2.05 0.516
0.543 2.1 0.542 2.1 0.53
0.550 2.15 0.557 2.15 0.544
0.556 2.2 0.572 2.2 0.558
0.562 2.25 0.587 2.25 0.572
0.569 2.3 0.602 2.3 0.587
0.575 2.35 0.617 2.35 0.601
0.582 2.4 0.632 2.4 0.615
0.588 2.45 0.648 2.45 0.63
0.595 2.5 0.663 2.5 0.645
0.602 2.55 0.679 2.55 0.659
0.608 2.6 0.695 2.6 0.674
0.615 2.65 0.711 2.65 0.689
0.621 2.7 0.727 2.7 0.704
0.628 2.75 0.744 2.75 0.719
0.635 2.8 0.76 2.8 0.734
0.642 2.85 0.777 2.85 0.75
0.648 2.9 0.794 2.9 0.765
0.655 2.95 0.8111 2.95 0.781
0.662 3 0.828 3 0.796
0.669 3.05 0.845 3.05 0.812
0.676 3.1 0.863 3.1 0.828
0.683 3.15 0.88 3.15 0.844
0.690 3.2 0.898 3.2 0.86
0.697 3.25 0.916 3.25 0.876
0.704 3.3 0.935 3.3 0.892
0.711 3.32 0.942 3.35 0.909
0.719 Max 3.32 0.942 3.4 0.925
0.726 3.45 0.942
0.733 3.5 0.959
0.740 3.55 0.976
0.748 3.6 0.993
0.755 3.65 1.011
0.755 3.7 1.028
3.75 1.046
3.8 1.063
3.85 1.081
 3.9 1.099
3.95 1.118
Max 3.95 1.118