Design Considerations: 

One Way Slab

1. Effective Depth (d)

• M.F. Modifiction factor from--- IS: 456, p.38.Fig-4
• Assume % steel 0.3 to 0.6%

2. Effective Span:

3. Reinforcement Requirements

• Plain bars-----------10 mm Ø min diaDeformed bars-----8 mm Ø min dia

• Plain bars-----------6 mm Ø min diaDeformed bars-----6 mm Ø min dia

4. Check for Cracking

5. Check for Deflection:

• M.F is Obtained from IS:456-200 P-38 Fig 4

6. Check for Development Length (Ld)

Two Way Slab

1. Effective Depth (d):

• For deflection control 
• L/d = 35 X M.F X 0.8
  • M.F. Modifiction factor from--- IS: 456, p.38.Fig-4
  • Assume % steel 0.3 to 0.6%
• Fs =  0.58 Fy X (Ast requierd / Ast Provied)
• Initially assume that Ast reqierd = Ast Provided 
• Fy = 250 N/ Sq.mm ----- Fs = 0.58 X 250 = 145 N/ sq.mm.
• Fy = 415 N/ Sq.mm ----- Fs = 0.58 X 415 = 240 N/ sq.mm.
• Fy = 500 N/ Sq.mm ----- Fs = 0.58 X 500 = 290 N/ sq.mm.

2. Effective Span:

• ClearSpan + d
• c/c of Supports

3. Load Calculations:

• Total Load = D.L. + F.L. + L.L.
  • Dead load of slab = (d x 25)
  • Floor Finishing load = (as floor finishing near 1 kn/sq.mm)
  • Live load = ( as per calculation)
• Factor Load = 1.5 x Total load

4. Mid Span Moment:

5. Effective Depth of Flexure:

6. Reinforcement in  Mild Strip :

• Pt=  50 (fck/fy)x( 1-√(1-(4.6xMu/Fck b.d.d)))
  • fck = strenth of concrete
  • fy = 415 N/Sq.mm
  • Mu = Sp 16 P 10 Table C =0.138 . fck . b.d.d= Mx

• Pt=  50 (fck/fy)x( 1-√(1-(4.6xMu/Fck b.d.d)))
  • fck = strenth of concrete
  • fy = 415 N/Sq.mm
  • Mu = Sp 16 P 10 Table C =0.138 . fck . b.d.d= My

7. Check for Cracking:

8. Check for Deflection:

• M.F is Obtained from IS:456-200 P-38 Fig 4

9. Check for Development Length:

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