In reinforced concrete design, what is the primary function of shear reinforcement (stirrups) in a flexural member?

• A. To resist bending moment and increase flexural strength.
• B. To resist shear forces, prevent diagonal cracking, and improve punching/shear capacity.
• C. To resist axial loads.
• D. To provide decorative finish.

Answer: (B)

Shear reinforcement in a flexural concrete member is intended to resist the shear forces that create diagonal cracks in the web and to raise the member’s shear and punching capacity. The stirrups cross the potential crack path and tie the concrete together, providing a path for shear forces and preventing or delaying diagonal cracking, which keeps the member from failing abruptly. This reinforcement works in conjunction with the main bending reinforcement (which handles the moment) but does not primarily increase bending strength or resist axial loads. It also isn’t for decoration.