Experimental investigation of the contribution of i and u shaped reinforcement planned to be used as an alternative to stirrups in reinforced concrete beams to shear strength

In this study, the feasibility of using I- and U-shaped shear reinforcements as an alternative to conventional full-anchored stirrups in reinforced concrete beams was experimentally investigated. Alternative shear reinforcements with different hook lengths and stirrup spacings were used to examine their effects on the load-carrying capacity, ductility, stiffness, and failure modes of the beams. A total of 18 reinforced concrete beam specimens were produced for the experimental study. Among these, six specimens were designated as reference specimens with conventional full-anchored stirrups, while the remaining 12 specimens featured hook lengths of 0 cm, 1.5 cm, and 3.5 cm, with stirrup spacings of 5 cm, 10 cm, and 15 cm. The beams were tested using a four-point bending test, and their load-bearing capacities, displacement values, and crack patterns were analyzed. The experimental results indicated that the specimens with 3.5 cm hook lengths exhibited the closest shear capacity performance to that of fully anchored stirrups. However, specimens with 0 cm and 1.5 cm hook lengths exhibited more sudden and brittle failures. Additionally, an increase in stirrup spacing resulted in a decrease in load-bearing capacity and led to earlier shear failures. While the alternative reinforcements were partially effective in enhancing ductility, they failed to achieve the strength level provided by conventional full-anchored stirrups. Based on the findings, it is not recommended to use I- and U-shaped reinforcements as a direct replacement for full-anchored stirrups. It has been determined that traditional stirrups should be preferred for structural elements where shear strength is critical. Future studies should conduct extended experiments with different reinforcement configurations and concrete classes to further investigate the applicability of these alternative shear reinforcement systems.