Behavior of reinforced concrete haunched beams subjected to cyclic shear loading

Final research results and interpretations of the testing of ten prototype simply-supported reinforced concrete beams (eight haunched and two prismatic) designed to develop a shear failure under cyclic loading are presented. Five beams (four haunched and one prismatic) were tested without shear reinforcement whereas the remaining five (four haunched and one prismatic) were tested with a shear reinforcement satisfying the minimum required for prismatic beams by the concrete norms of Mexico’s Federal District Code (MFDC). These haunched beams are identical in geometry and reinforcement to a set of haunched beams previously tested under static loading. These additional cyclic testing confirmed the usefulness of a proposed equation to estimate the shear strength of reinforced concrete haunched beams, taking into account parameters such as the haunch angle, the concrete compressive strength, the shear reinforcement and the contribution of the inclined longitudinal reinforcement. From the obtained results, it can be observed that haunched beams have a different cyclic shear behavior with respect to prismatic beams, having higher deformation and energy dissipation capacities, among other reasons, because non-prismatic beams favor an arching action in the haunched length as the main resisting mechanism, that develops smoother cracking patterns.