Behaviour of concrete-filled steel columns subjected to lateral cyclic loading

This paper reports the findings of an experimental study that was undertaken to investigate the cumulative damage of in-filled steel columns subjected to quasi-static loading. The parameters studied are, the diameter-to-thickness ratio of the steel tube and two types of in-fills namely Plain cement concrete and Steel fiber reinforced concrete. This paper summarizes the results of phase I testing that consisted of benchmark tests to establish the hysteresis behaviour under variable amplitude cyclic loading and phase II testing that consisted of constant amplitude cyclic loading that focused on the effects of amplitude and number of cycles on damage accumulation of in-filled columns. Findings of these studies highlight the significant increase in ductility and energy absorption capacity and decrease in the damage index of Steel fiber reinforced concrete-filled steel columns compared to plain cement concrete-filled columns. A simplified equation for cumulative damage has been proposed to predict the damage index of in-filled columns. This index can be used as a measure for predicting the safety of new and existing in-filled columns against earthquake.