What is the minimum size and location of rebar in a footing for a monolithic slab?

The minimum size and location of rebar in a footing for a monolithic slab is essential for ensuring the structural integrity and load-bearing capacity of the slab. The correct answer reflects that rebar must be positioned in a way that effectively resists tensile forces, which are more prevalent in the middle third of the footing where bending moments are highest during load application.

In structural engineering, especially regarding concrete slabs, the top section of a footing typically experiences compressive forces, while the bottom section experiences tensile forces. By placing rebar in the middle third, it provides optimal reinforcement where the tensile stresses are most critical, enhancing the slab's performance under load and reducing the risk of cracking or failure.

The choice of rebar size also matters, as smaller sizes like 1/2 inch may not provide sufficient strength, particularly in areas of high tension, while larger rebar sizes could be more than necessary without justifiable benefits. Therefore, using 2/4 inch rebar in this specified location aligns with standard practices for structural reinforcement in monolithic slab design.