Why do we use torsional reinforcement in two way slab?
Torsion reinforcement shall be provided at any corner where the slab is simply supported on both edges meeting at that corner and is prevented from lifting unless the consequences of cracking are negligible.
What is the length of torsion reinforcement in two way slab?
Torsional reinforcement is provided in the form of a grid or mesh both at the top and bottom of the slab. i.e. lx/5. The total area of torsional steel provided in each of the four layers should not be less than: (i) 0.75 Astx(+ve) If both the meeting edges are discontinuous i.e. edge 1.
How are two way slabs reinforced?
Slabs are supported by beams on all the four sides. Main Reinforcement is provided along both the directions in two way slabs. Loads are carried along one direction in one way slab. Loads are carried along both the directions in two way slabs.
How does torsion occur in slab?
Perimeter beams in reinforced-concrete buildings are subjected to considerable torsion from slab negative bending moments. It was also observed that the slab corners tend to shift torsional failure (which occurred at the twisted beam near the support) to about one beam depth away.
What is torsion reinforcement in slab?
Corner reinforcement are also called as torsional reinforcement. Torsional reinforcement shall be provided at corner of two way slab. The torsional moment are high near the corner therefore, torsional reinforcement is essential to prevent corner slab from lifting and prevents cracks.
How is torsional reinforcement provided in beam?
On several situations beams and slabs are subjected to torsion in addition to bending moment and shear force. Loads acting normal to the plane of bending will cause bending moment and shear force. However, loads away from the plane of bending will induce torsional moment along with bending moment and shear.
What is torsional reinforcement?
What is the difference between one way slab and two way slabs?
In one way slab, the load is carried in one direction perpendicular to the supporting beam. In two way slab, the load is carried in both directions. The deflected shape of the one-way slab is cylindrical. Whereas the deflected shape of the two-way slab is a dish or saucer-like shape.
Which is better one way or two way slab?
The one-way slab is economical up to a span of 3.6 meters. Whereas the two-way slab is economical for the panel sizes up to 6m × 6m. In one-way slab quantity of steel is less. In two-way slab quantity of steel is more as compared to the one-way slab.
What is torsion reinforcement?
What is torsion in reinforced concrete?
If external loads act far away from the vertical plane of bending, the beam is subjected to twisting about its longitudinal axis, known as torsion, in addition to the shearing force and bending moment. If the member is not adequately reinforced for torsion, a sudden brittle failure can occur.
What is torsion reinforcement in concrete slab?
At corner C1 – The slab is discontinuous on both the sides, the torsion reinforcement shall consist of top and bottom bars each with layers of bar placed parallel to the sides of the slab and extending a minimum distance of one fifth of the shorter span from the edges.
What is the reinforcement in two way slab?
In two way slab main reinforcement is provided along both direction. Slabs could be simply supported, continuous or cantilever. In two way slab the corners may be held down by restraints or may be allowed to lift up. Additional torsion reinforcement is required at corners when it is restrained against uplifting as shown in Fig.1.
How much torsional reinforcement should be provided at discontinuous corner?
At the discontinuous corner, torsional reinforcement should be provided. It is provided in two layer. Each layer should have area per unit width equal to 75% of mid-span tension reinforcement for adjacent edge of a slab is discontinuous. But if only one edge is discontinuous then 37.5% will be okay.
Why corner steel is provided in a two way slab?
To resist that corner steel is provided. Corner reinforcement are also called as torsional reinforcement. Torsional reinforcement shall be provided at corner of two way slab. The torsional moment are high near the corner therefore, torsional reinforcement is essential to prevent corner slab from lifting and prevents cracks.