What is Rebar ?

Definition of Rebar in Construction
Reinforcing steel that is embedded within a concrete structure. The installation of rebar occurs when the formwork is in place and prior to the placement of the concrete within the formwork.

The placement of the reinforcing steel within a structural component is engineered by a structural engineer. The structural engineer will study and determine the load calculations therefore determining the forces within the structural component being designed. Depending on the type of loads and stresses, the reinforcing bars will be both sized and located accordingly.

Reinforcing bar or steel is better in tension than compression. Concrete is stronger in compression than in tension. The location o f the reinforcing bars are positioned to accept the tensile forces developed as the structural component is loaded and the mass of concrete is placed in the areas of compression. For example ,the reinforcing in a typical footing is located within the lower 1/3 of the footing due to the tensile bottom stresses and the mass of concrete is located in the upper 2/3’s of the footing due to the distribution of compressive force.

In structural slabs the reinforcing alternates from the top of the slab over the supporting columns to the bottom of the slab at the mid-span between the columns. This reinforcing bar placement is due to the alternating sequence of the compression and tensile forces across the slab.