What type of bar is specifically meant to provide tension without bonding to surrounding concrete?

The type of bar that is specifically designed to provide tension without bonding to the surrounding concrete is known as a plain bar. Plain bars have a smooth surface, which prevents them from developing significant bond strength with the concrete. This lack of bonding is intentional, as it allows the bar to move independently within the concrete, enabling it to effectively carry tensile loads without being constrained by the surrounding material.

In scenarios where tensile stress needs to be accommodated but with limited interaction with the concrete, plain bars are particularly useful. Their smooth surface reduces the friction and mechanical interlock with the concrete, facilitating movement and allowing the tensioning mechanism to function as intended. This characteristic makes plain bars distinct from deformed bars, which are designed to bond well with concrete for enhanced tensile capacity.