What do stirrups in beams primarily resist?

Stirrups in beams primarily resist diagonal tension. This is crucial in reinforced concrete beams, as they help to counteract the diagonal cracks that can develop when the beam experiences shear forces. When a beam is loaded, it often not only carries vertical loads but also undergoes shear stress. The stirrups, which are typically made of tied steel reinforcement, are specifically designed to provide additional support, allowing the beam to effectively transfer and resist these shear forces.

As the concrete alone has limited tensile strength, the inclusion of stirrups enhances the beam's ability to withstand shear and the resulting tensile stresses that occur at an angle to the beam's length. This helps maintain the structural integrity of the beam and prevents failure. Understanding this function is key to ensuring that beams are appropriately designed to handle the loads they will encounter in real-world applications.