This construction article provides brief discussion on slabs reinforcement detailing.
Reinforcement detailing of a slab is influenced by its support conditions. Slab is usually supported on walls or beams or columns.
Concrete surfaces, which bear extreme load due to heavy trucks or machinery, require concrete rebar reinforcement. Rebar reinforcement resists cracks in concrete which may occur because of tension forces. Rebar facilitates to prevent cracks from being expanded largely by controlling cracked slabs from moving apart.
The objective of a slab is to cover spaces by means of roof or floor.
Slab is laid on walls or beams or columns.
Slab that is supported directly with columns are defined as flat slab.
Slabs come in the form of simply supported, continuous or cantilever.
In two way slab, the corners are held down by restraints or allowable to lift up.
Supplementary torsion reinforcement is necessary at corners if it is constrained upon uplifting.
The depth of the slab is settled on the basis of the span to depth percentage that is mentioned in the standard IS456-2000. Least reinforcement is 0.12% for HYSD bars and 0.15% for mild steel bars.
The highest diameter of the bar that is applied in slab should not be over 1/8 of the total depth of slab.
Highest spacing of main bar is limited to 3 times effective depth or 300 mm either is less.
For distribution bars, the highest span is indicated as 5 times the effective depth or 450 mm either is less.
Normally, 15 mm to 20 mm cover is arranged for the main reinforcements.
Substitute main bars should be cranked adjacent to support or bent at 1800 at the edge and then expanded at the top within the slab.
Torsion reinforcement should be arranged in the slab so that cracks are developed at the corners of the slab due to extreme torsional moment. The torsional moments are high near the corner of the slab.