Reinforcement Detailing of Reinforced Cement Concrete Slabs

Reinforcement Detailing of Reinforced Cement Concrete Slabs

Reinforcement listing of a slab is accomplished according to its support shapes. Slab could be braced on walls or joists or pillars. Slab supported straightforwardly through columns are known as flat slab. 

Slab supported on 2 sides and bending happens primarily in 1 direction particularly is known as One Way Slab. Alternatively, while slab is supported on all 4 sides and bending happen in 2 directions are declared to be Two Way Slab. 

The slabs possessing ratio of longer length to its smaller length (Ly/Lx) higher than 2 is known as one way slab or else as two way slab. In one way slab, major reinforcement is along the side of smaller direction and the reinforcement along the side of longer direction is known as distribution steel. 

In two way slab, major reinforcement is offered along both directions. Slabs might be just supported, continuous or cantilever. In two way slab, the edges could be covered up through restraints or could be permitted to elevate. Extra torsion reinforcement is needed at edges once it is controlled in opposition to uplifting.

Breadth of the slab is determined in accordance with span to depth ratio stated in IS456-2000. Minimum reinforcement is 0.12% for High Yielding Strength Deformed bars and 0.15% for mild steel bars. The width of bar usually utilized in slabs are: 6 millimeter, 8 millimeter, 10 millimeter, 12 millimeter and 16 millimeter. 

The highest width of bar utilized in slab must not go beyond 1/8 of the overall breadth of slab. Highest distancing of major bar is limited to 3 times effective depth or 300 millimeter whichever is less. For distribution bars, the highest distancing is fixed as 5 times the effective depth or 450 millimeter either is less. Minimal apparent cover to reinforcements in slab relies on the stability standards and this is described in Indian Standards 456-200. Normally 15 millimeter to 20 millimeter cover is offered for the major reinforcements. 

Alternating main bars can be twisted close to support or might be twisted at 1800 at the border and then expanded at the top within the slab. Torsion reinforcement will be offered at any curve where the slab is easily supported on both margins joining at that bend and is restrained from lifting except the aftereffects of cracking are insignificant. It will comprise top and base reinforcement, separately with layer of bars set parallel to the sides of the slab and expanding from the borders a minimal distance of 1/5th of the smaller distance.

The region of reinforcement per unit breadth in each of these 4 layers will be 3 quarters of the field needed for the greatest mid-span moment per unit breadth in the slab. Torsion reinforcement up to half that is explained above will be offered at a curve surrounded by borders over only one of which the slab is continual. The sketch displaying the listing of reinforcement possesses a design demonstrating usual reinforcement in both direction and fractional heights.


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