# Design steps of one way slab

How to calculate the steel for rcc slab?

Design steps of one way slab

1.Depth of slab
d= lx/20 * M.F.(M.F. = Modification factor)
Assume the dia of bar(8,10,12) and Final overall depth
D= d+15+0/2
d= d-15-0/2

2. Effective Span

This is taken as the lesser of the followings
a) Center to center distance between followings
L= lx + t
L= lx + d

1m width of the slab and find out the total udl
a) W = (Self weight + Live Load + Floor finish)
b) Find factor load
Wu = 1.5 * w

4. Factor bending moment

Mu = Wu * l^2/8

5. Equating
Mu limit to Mu find the depth req. if it is less than‘d’ than O.K otherwise Increase D & repeat 2, 3, and 4
Mulimit = Mu

6. Area of main steel
Pt = 50fck/fy (1– 4.6 Mu/fck bd^2)
Ast = Pt/100*100*d

7. Spacing of main steel S = Area one bar*1000/Ast
Check:
a) 3d b) 450 mm

8. Distribution Steel
Astd=0.15 % of Ag -Fe 250(mild)= 0.12% of Ag – Fe 415/5000 (torque)Ag = b.D

9.Spacing of distribution steel
S= Area one bar*1000/Astd
Check:a) 5d b) 450 mm

10.Check for depth
a) zv = V/bd
b) Pt - Zc
c) Zv < Zc
No shear reinforcement req.