Experimental study on hysteresis performance of RPC-filled circular steel tube (RPC-FST) columns

This study designs and fabricates nine RPC-filled circular steel tube (RPC-FST) columns to investigate their compression-bending hysteresis performance and seismic behavior. It conducts low-cycle reciprocating tests on the columns to obtain and analyze the load-displacement hysteresis and skeleton curves of the nine RPC-FST columns. This research also examines the effects of the axial compression ratio and the diameter-to-thickness D/t) ratio on the load-displacement skeleton curves and the seismic performance indices such as the ductility coefficient and equivalent viscous damping coefficient of the specimens. The test results revealed that the hysteresis loop of the RPC-FST column is plump and fusiform-shaped without pinching, indicating that the RPC-FST column possesses a favorable energy dissipation capacity. The ultimate drift ratios of the nine specimens range from 3.5 % to 7.9 %, and their ductility coefficients range from 3.2 to 4.6, indicating that the RPC-FST columns have good ductility and deformation capacity. The specimen's ductility coefficient decreased as the axial compression ratio and D/t ratio increased. Finally, the compression-bending capacity of RPC-FST columns is calculated based on the current GB50936–2014, EC4, AIJ, and AISC-LRFD codes.