Experimental Study and Numerical Analysis of CFSST Columns Subjected to Lateral Cyclic Loading

Abstract

An experimental study and numerical modeling were carried out to investigate the behavior of concrete-filled stainless-steel tube (CFSST) columns subjected to constant axial compression combined with lateral cyclic loading. Eighteen specimens with varied cross-sectional configuration, steel ratio, and axial compression ratio were tested. The failure pattern, load versus deformation curve, bearing capacity, stiffness degradation, accumulated energy dissipation, and ductility were comprehensively investigated. The experimental results revealed that the failure pattern of the stainless-steel tube is mainly a lantern-shape local buckling beside the rigid fixture along with crushing of core concrete at the buckling position. CFSST specimens under lateral cyclic loading generally possessed stable fusiform hysteretic curves, with their initial loading and unloading stiffness increased with increasing cross-sectional steel ratio and axial compression ratio. The axial compression ratio has a more evident influence on the mechanical response of the specimens than the steel ratio, whereas an increase of the bearing capacity, energy dissipation, and ductility index was detected when increasing the steel ratio or decreasing the axial compression ratio. Square specimens have lower ductility and more rapid stiffness degradation compared with circular ones. A finite-element analysis (FEA) model was also established to simulate the behavior of CFSST columns subjected to constant axial compression combined with lateral cyclic loading. Good accuracy was achieved when comparing the predicted response and experimental observations.