Seismic performance of GFRP tube concrete-encased steel composite columns under axial compression

Abstract

A glass fiber-reinforced polymer (GFRP) tube concrete-encased steel (GTCES) composite column is a novel column type comprising an outer GFRP tube containing a concrete core and an encased steel section. Although previous studies have examined the static performance of GTCES columns, their seismic performance has not yet been investigated. Therefore, in this study, six GTCES columns with different steel ratios, GFRP tube thicknesses, and axial compression load ratios were tested under combined reversed cyclic lateral loading and static axial compression conditions. The results were used to investigate the influences of these parameters on the failure mode, hysteretic behavior, skeleton curve, ductility coefficient, stiffness, energy dissipation, and strength degradation of GTCES columns. They were found to exhibit favorable seismic performance with excellent ductility and energy dissipation. The steel ratio had a considerable influence on the energy dissipation and carrying ability of the column, and the axial compression load ratio increased its lateral load capacity. Finally, a simplified hysteretic restoring force model for the load-displacement relationship of GTCES columns was established and verified.