Development and seismic performance of staggered and out-of-plane joints between concrete-filled steel tubular column and reinforced concrete beam

This article presents a staggered and out-of-plane connection between concrete-filled steel tubular column and reinforced concrete beam (SOC-TCB). SOC-TCB is taken from the basement roof joint of Suning center, which is a height of 341.85 m in China. In this joint system, the H-shaped steel brackets are welded with steel tube to transfer shear and moment. Moreover, the reinforcing bars are interrupted by steel tube and lapped with steel bracket. To investigate the seismic behavior of SOC-TCB, four types of SOC-TCBs were tested under reversal cyclic loading. The differences between specimens were staggered height and out-of-plane angle. Seismic performance was evaluated based on hysteretic behavior, failure mode, shear deformation, rotational deformation, and energy dissipation. The results showed that the shear deformation of joints was extremely small and the plastic hinges were formed at reinforced concrete beams. Due to insufficient anchorage length of longitudinal bars, anchoring failure was found in the reinforced concrete beams. However, SOC-TCB showed better seismic behavior as long as sufficient anchorage of longitudinal bars was ensured.