Experimental Study on Seismic Behaviors of a New Type of Transferring Joint with Top Steel Column Embedded to the Panel Zone

Abstract

Based on a practical project in China, a new type of composite transferring joint is put forward as the key part to realize the structural transformation from the upper steel frame to the lower RC frame. The joint is accomplished by inserting the steel column into the concrete of the panel zone. The longitudinal rebars of the bottom RC column are placed near the studs welded to the steel column wall, so the vertical internal force can be transferred in an indirect way. To study the seismic performance of this kind of transferring joint, four specimens were tested under cyclic loading. Axial compression ratio and upper-panel zone concrete were selected as the key investigating parameters. The test results show that the failure mode of the specimens includes plastic hinge failure at the beam ends, concrete crushing failure at the bottom of the RC column, and shear failure at the panel zone. The force displacement hysteretic curves are very plump and the specimens have high energy dissipation capacities, indicating this new type of transferring joint has a good seismic performance. Furthermore, increasing the axial compression ratio can effectively improve the stiffness and bearing capacity of the joint, as well as the energy dissipation capacity. The existence of the upper-panel zone concrete is of little effect under large axial compression ratio, while under small axial compression ratio, it can significantly increase the stiffness and the energy dissipation capacity of the joint, and increase the bearing capacity to some extent.