Experimental Investigation on Cyclic Behavior of Reinforced Concrete Coupling Beams Under Quasi-static Loading

The current status of the reinforcement layouts stated in the codes and frequently used in new construction areas needs to be evaluated and determining its effects on the behavior of structural elements may provide essential contributions to the field. For this purpose, conventionally reinforced, diagonally reinforced (confinement of individual diagonals),and diagonally reinforced with full confined section concrete coupling beam specimens were designed according to ACI 318-14 and Turkish Earthquake Code 2018 in this study. ½-scale test specimens with aspect ratio two were tested under quasi-static cyclic loading using a new complex experimental setup. According to the results obtained, while for conventionally reinforced coupling beams ductile hysteretic behavior remained at 2.0% drift, for diagonal reinforced coupling beams it sustained up to 4.0% drift. Although the diagonal reinforcement enhanced ductility capacity of coupling beams compared to conventionally reinforced coupling beams having a comparably low post-elastic behavior, high ductility demands in the code requirements did not meet. For the same reinforcement ratio and layout, individual confinement around diagonal bars retarded bar buckling and ultimate strength and ductility capacity increased slightly compared to diagonally reinforced coupling beam with full confined section. After all, bar buckling that occurred after the life safety performance level given in the codes was seen at 3.5–4.0% drift. Diagonal reinforcing bars ensured life safety performance level up to 4.0% drift, but it remained at 3.0% drift for conventional reinforcement.