Reinforced concrete slab is an essential structural element in building, it is commonly used in raft foundation or ground floor of a storey building to distribute load to the beams and columns while resisting bending, shear and cracking.
Reinforced concrete slab consists of steel bars that are tied in a grid pattern which are embedded in concrete to enhance its tensile strength.
Slab reinforcement design beggings with calculation of slab dead load and imposed load, the slab span and its thickness, structural analysis is carried out to determine whether the slab can carry the load for which it was designed for.
One way slab: A slab is classified as one way slab when it has support only on two opposite ends and also when the ratio of the longer span to shorter span is greater than two (L/B > 2) . In this type of slab, load is transferred in one direction along the shorter span and its main reinforcement is provided along the shorter span while the secondary reinforcement is place perpendicular to the main reinforcement.
Two way slab: A slab is classified as two way when it is supported on its four sides, and the ratio of longer span to shorter span is less than two, (L/B <2). In this type of slab, load is distributed in two directions to the supporting column.
The pictures seen in this post shows a building that is undergoing reinforcement at its first floor
Note: Every action as regards the slab reinforcement was carried out from the detailed information in the structural drawing.
1<. 12 mm steel reinforcement bar was use at a uniform spacing of 200mm.
2. The butom bars is usually refers to as tension bar because they resist tension stresses at the bottom of slab. These tension bars are positioned along the shorter span of the slab.
3. The top bars also refers to as compression bar runs perpendicular to the tension bars. These bars helps to resist comprehensive stress.
4. At the point where a bar ends, another bar is lapped at 1 meter length to continue with the existing bar.
5. At the fixed end, the reinforcement is returned at a length of (slab span ÷ 4) to anchor into the beam.
6. Cover block is used to separate the reinforcement from resting on the formwork, this helps to provide efficient concrete cover for the rebar.
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