What are the support reinforcing bars at the desired level in concrete construction called?

In concrete construction, the support reinforcing bars that are positioned at the desired level are called bolsters or chairs. These are specialized devices used to hold the reinforcing bars (rebar) in place while concrete is being poured. By maintaining the correct positioning of the rebar, bolsters or chairs ensure that the steel reinforcement is properly embedded within the concrete, which is essential for the structural integrity and load-bearing capacity of the final product.

Using bolsters or chairs allows for effective placement of rebar at designated heights, ensuring that the reinforcement is strategically located where it can provide the maximum benefit against tensile stresses. This alignment is crucial for ensuring the durability and performance of the reinforced concrete.

Other choices like reinforcement strips, support bars, and steel grids may be related to reinforcing concrete but do not specifically refer to the devices that ensure proper elevation and spacing of the rebar during the pouring of concrete. Reinforcement strips typically refer to a different method of reinforcing materials, and support bars usually do not describe the specific role of maintaining rebar elevation. Steel grids can be used for reinforcement but are not the same as bolsters or chairs used for positioning the rebar.