Abstract:To investigate the impact of environmental temperature in alpine regions on the seismic performance of circular concrete-filled steel tubular (CFST) columns, a series of quasi-static tests were conducted on circular CFST columns at four different temperature conditions. The failure characteristics, bearing capacity, hysteresis characteristics, stiffness degradation, ductility, and energy-dissipation capacity of each specimen were analyzed, and the influence of temperature on the seismic performance of CFST columns was revealed. The experimental results showed that the hysteresis curves of specimens under different temperature conditions all present a spindle shape without obvious pinching phenomenon. The typical failure modes of specimens are basically the same at different temperatures: a circle of bulging waves occurs at the bottom of the steel pipe, the core concrete is crushed, and the steel pipe is torn. The lower the temperature, the earlier and more severe the failure of CFST columns. Compared with the working condition at a normal temperature (20 ℃), the horizontal bearing capacities of CFST columns at 0 ℃, -20 ℃, and -40 ℃ are increased by 3.08%, 6.15%, and 10.08%, and the initial stiffness are increased by 16.9%, 30.3%, and 50.0%, respectively, whereas the ductility coefficients are decreased by 8.6%, 14.6%, and 16.9%, respectively. The lower the environmental temperature, the faster the rate of stiffness degradation. Temperature change has a significant impact on the seismic performance of CFST columns, so the adverse effects of low environmental temperatures on the structure should be considered in the seismic design of CFST structures in alpine regions.
