DESIGN OF EXTERNAL PLATFORM Self Wt. of platform (for 1m width) = 0.15 x 2.5 = 0.375 T/m per m width. Load from handrail and toe = 0.15 x 0.15 x 2.5 + 0.1 = 0.16 T/m Live load = 500 Kg/m 2 For 1m width of slab moment M=0.16 x 1.075+ (0.5 + 0.375) x 1.15 2 /2 = 0.75 Tm Say 0.8 Tm per m width Assuming the clear cover as 20 mm and 12mm TMT bar as main reinforcement, Effective depth, d = 150 - 20 - 6 = 124 mm d reqd. = √ (0.8 x 10 7 ) / (1.158 x 1000) = 83.11 mm However providing D=150mm, d=124 mm Ast = 0.8 x 10 7 = 257 mm 2 /m 275 x 0.91 x 124 Distribution steel required= 0.12/100 x 150 x 1000 = 180 mm 2 Provide 12 mm TMT bar @ 150 C/C (Ast = 7.54 cm 2 ) as main reinforcement and 10 mm TMT bar @ 200 C/C (Ast = 3.9 cm 2 ) as distribution reinforcement.
DESIGN OF EXTERNAL PLATFORM Self Wt. of platform (for 1m width)
=0.15 x 2.5 =0.375 T/m per m width. Load from handrail and toe=0.15
x 0.15 x 2.5 +0.1 =0.16 T/m Live load= 500 Kg/m2 For 1m width of
slab moment M=0.16 x 1.075+(0.5 +0.375) x 1.152/2 =0.75 Tm Say 0.8
Tm per m width Assuming the clear cover as 20 mm and 12mm TMT bar
as main reinforcement, Effective depth, d =150 - 20 - 6 =124 mm
dreqd.= (0.8 x 107) / (1.158 x 1000) = 83.11 mm However providing
D=150mm, d=124 mm Ast =0.8 x 107 =257 mm2/m 275 x 0.91 x 124
Distribution steel required=0.12/100 x 150 x 1000 =180 mm2 Provide
12 mm TMT bar @ 150 C/C (Ast =7.54 cm2) as main reinforcement and
10 mm TMT bar @ 200 C/C (Ast =3.9 cm2) as distribution
reinforcement.
