Experimental research on axial mechanical properties of circular CFSST columns after exposure to temperature and sliding

This paper presents experimental investigations on axial mechanical properties of circular concrete-filled stainless steel tube (CFSST) columns after exposure to temperature and sliding. A total of 117 CFSST specimens were tested under axial compression loading with four factors (i.e., tube thickness, temperature, duration, and concrete compressive strength) considered. Test results indicated that the initial stiffness of circular CFSST short columns was degenerated due to high-temperature sliding. Circular CFSST specimens exhibited a 50.9% lowest residual strength at 1000 degrees C. The influence of high-temperature duration on the residual strength of circular CFSST short columns was limited. The residual strength of specimens was positively correlated with the thickness and concrete compressive strength. All circular CFSST columns after exposure to temperature and sliding experienced an outward local buckling under axial compression. In addition, the parameters formulae of residual strength for circular CFSST columns after exposure to temperature and sliding are proposed, which achieve sufficient accuracy. The research could offer valuable references for strengthening circular CFSST columns after fire.