Design of Staircase Slab
Priliminary data
Height of floor 3 Width of flight
Grade of Concrete,M 20 Grade of steel, Fe
Dia of bar used (mm) Main 10 Clear cover (mm)
Riser 150 Density of concrete
Tread 250 Distributor bar
Live Load 3.00 KN/m2
Flight c/c 3.04 m (Landing m)
SQRT R2+T2 291.5 mm
Effetive Span IS 456-2000, Cl.22.2
Effetive Span =c/c distance 3880 mm
between the supports
Assume waist slab thickness =L/20 194 mm 200
Assume waist slab thickness = 125 mm
Effective depth 175 mm
Load calculation
A)Loads on going
a) Self weight on waist Slab 5.83
b) Self weight of steps 1.88
c)Floor Finish 1.50
Live load 3.00
Total load 12.21
Total factored load per meter width , Wu 18.31
B)Loads on landing
a) Self weight of Slab 5.00
c)Floor Finish 1.50
Live load 3.00
Total load 9.50
Total factored load per meter width , Wu 14.25
Design moment
R1 33.7
Max factored moment occurs at the S/C of zero shear,located at X 1.84
Mu 57.2
Main Reinforcement
R=(Mu/bd2) 1.87
(pt/100)=(Ast/bd) Ast=fck/2fy(1-sqrt(1-4.6R/fck) 0.00490
Ast required 857
Required spacing of 10mm dia bar, spacing 91.7
Distributors
Ast required =0.12%bD 240
Spacing 10dia bars 327.3
Say 300
Spacing 8 dia bars 209.5
Say 200
Provide 10 dia bars @ 300 c/c
Provide 8 dia bars @ 200 c/c
1.05
500
20
25
8
0.825
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mm2/m
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