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Design Requirements for Concrete Slab Design - Design of slabs





We are goings to learn what are design requirements of concrete slab design as per standard IS codes.



1.Effective Span for concrete slab design

For simply supported slab

  • Minimum of clear span plus effective depth of slab 
  • Center to centre distance between the supports

For cantilever slab

  •    Length up to face of support+Half the effective depth.
  •    Where it forms end of a continuous slab, the length of centre of support shall be taken.

2.Limiting Stiffness

For span up to 10m, the Basic values of span to depth ration are given below
  1. Cantilevers-7
  2. Simply supported- 20
  3. Continuous- 26

3.Minimum Reinforcement for concrete slab design

As per clause 26.5.2.1 of IS 456-2000, the minimum reinforcement shall not be less than 0.15% of gross sectional if mild steel is used and 0.12% of gross sectional area if HYSD bars are used




4.Maximum diameter of bars 

The diameter of the bar shall not exceed 1/8 of total thickness of the slab.




5.Spacing of main reinforcement

The spacing of main reinforcement in slabs shall not be more than three times the effective depth of solid  slab or 300mm whichever is less

6.Distribution reinforcement for concrete slab design

The area of distribution reinforcement shall not be less than 0.15%of gross cross-sectional area if plain bars are used and 0.12% of high yield strength deformed bars are used.
The spacing of distribution reinforcement in slabs shall not be more than five times the effective depth of slab or 450mm whichever is less

7.Cover to reinforcement

The minimum nominal cover provided to slabs is 20mm.(If the diameter of bar < 12mm and mild exposure)




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