Comparative performance of sub-standard interior reinforced concrete beam–column connection with various joint reinforcing details

Abstract

This paper discusses the effect of some important parameters on cyclic behavior of sub-substandard interior beam–column connection. The objective is to investigate the effect of joint shear stress, anchorage bond of longitudinal beam bar within the joint and horizontal joint reinforcements on the joint performance. The experiment consisted of five half-scale beam–column specimens. The control specimen (J1) represented a typical non-ductile beam–column joint in mid-rise RC buildings constructed in low seismic zone. In specimen J2, the bond between concrete and longitudinal bars was completely removed initially. In specimen J3A and J3B, a substantial amount of horizontal joint reinforcement was provided in joint core. In specimen J4, the column size was enlarged to reduce shear stress in joint. The experimental result demonstrated brittle joint shear failure in control specimen (J1), specimens J3A and J3B, beam splitting failure in specimen J2 and ductile flexural failure in specimen J4. Based on experimental results, it was found that the initial lost of bond did not cause a substantial reduction in joint capacity. Moreover, provision of substantial horizontal joint reinforcements in specimen J3A and J3B did not produce a comparable improvement in the seismic performance. With increased column size in specimen J4, the energy dissipation characteristics were greatly improved as indicated by large spindle-shaped cyclic loops.