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Reinforced Concrete Slab Design and Detailing Guide IS456: 2000

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Reinforced concrete slab design and detailing guidelines for depth of slab, loads on slab, reinforcement guide for one-way and two-way slabs as per IS 456:2000 have been tried to present here. Following are the RCC Slab Design and Detailing guidelines:

Reinforced Concrete Slab Design Guidelines

a) Effective span of slab:

Effective span of slab shall be lesser of the two
  1. L = clear span + d (effective depth)
  2. L = Center to center distance between the support

b) Depth of slab:

The depth of slab depends on bending moment  and deflection  criterion.  the trail depth can be obtained using:
Type of support Fe-250 Fe-415
Simply supported L/35 L/28
Continuous support L/40 L/32
Or, the following thumb rules can be used:

c) Load on slab:

The load on slab comprises of Dead load, floor finish and live load. The loads are calculated per unit area (load/m2). Dead load = D x 25 kN/m2 ( Where D is thickness of slab in m) Floor finish (Assumed as)= 1 to 2 kN/m2 Live load (Assumed as) = 3 to 5 kN/m2 (depending on the occupancy of the building)

Detailing Requirements of Reinforced Concrete Slab as per IS456: 2000

a) Nominal Cover:

For Mild exposure – 20 mm For Moderate exposure – 30 mm However, if the diameter of bar do not exceed 12 mm, or cover may be reduced by 5 mm. Thus for main reinforcement up to 12 mm diameter bar and for mild exposure, the nominal cover is 15 mm.

b) Minimum reinforcement:

The reinforcement in either direction in slab shall not be less than

c) Spacing of bars:

The maximum spacing of bars shall not exceed

d) Maximum diameter of bar:

The maximum diameter of bar in slab, shall not exceed D/8, where D is the total thickness of slab. Read More: Basics of Reinforced Concrete Slab Design Types of Design and Detailing Errors in Construction and their Prevention Causes of Excessive Deflections in Reinforced Concrete Slabs Types of Economical Floor Systems for Reinforced Concrete Buildings
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