What is Corner Reinforcement of Slab and why it is provided?
According to ACI 318-14, Section 8.7.3, exterior corners of slabs that are supported by stiff elements such as, walls and edge beams. The torsional moment are high near the corner therefore, torsional reinforcement is essential to prevent corner slab from lifting and prevents cracks.
Corner reinforcement must be provided in the top and bottom of the slab to resist these bending moments. According to ACI 318-14, Section 8.7.3.1.3, reinforcement must be placed parallel to the diagonal in the top of the slab and perpendicular to the diagonal in the bottom of the slab.
Reinforcement parallel to the slab edges is permitted to be used instead of the diagonal bars.
This layout is preferred because of ease of constructability.