Experimental cyclic behavior of code-conforming exterior wide beam-column connections

Reinforced concrete (RC) frames with wide beams are efficient systems for resisting against lateral and gravity loads. However, there are limited experimental studies on the performance of wide beams under cyclic lateral loading. This paper presents the results of an experimental investigation on seismic behavior of RC exterior wide beam-column connections. Four 3:5 scale wide beam-column connections were tested under combined constant axial and quasi-static cyclic lateral loads. Different spandrel beam types including conventional and wide beam and three column geometries (square, rectangular and circular) were used in the specimens. The specimens all were designed in accordance with ACI 318-14 and ACI 352R-02 provisions. Special attention was given to reinforcement detailing of wide beam and spandrel beam at the joint area. The test results showed that although all specimens were code conforming and similarly designed for interaction of bending, shear and torsion, more torsional cracks developed in the cases that transverse beam was wide. The performance of all the specimens was satisfactory in terms of strength, ductility and energy dissipation capacity. It was observed that the load transfer mechanism from wide spandrel beam to column is a combination of torsion and bending. In the specimen with circular column, higher displacement ductility and lower energy dissipation were observed compared with the similar specimen containing square column. Besides, the importance of fine reinforcement detailing for wide and spandrel beam at the joint zone was confirmed by the test results.