Performance of steel-reinforced concrete-filled square steel tubular members under sustained axial compression loading

Abstract

Steel-reinforced concrete-filled steel tubular (SRCFST) members have been used in the construction owing to the superior structural performances, and are usually subjected to sustained loads during their service period. The study aims to evaluate the structural behaviour of SRCFST columns under long-term sustained load. Twenty square SRCFST columns were designed and tested to investigate the influence of sustained load on the compression behaviour. Various parameters, namely, long-term load ratio, steel ratio of profiled steel and slenderness ratio are considered to evaluate their influences on the creep in sustained load, failure mode, load-deformation curve and load–strain relation of the SRCFST columns respectively. Furthermore, the finite element (FE) model was established via software ABAQUS and its reliability was verified. The results indicate that the long-term load ratio has slight effect on the ultimate strength of SRCFST specimens. When considering the long-term load, the ultimate strength of SRCFST stub columns under axial compression nearly remains unchanged, while the load-carrying capacity for long columns actually decreases. Finally, a simplified calculation method considering long-term loading effect for the load-carrying capacity index of SRCFST columns under axial loading is proposed through parametric regression.