Behavior of concrete-filled circular steel tubular stub columns exposed to corrosion and freeze-thaw cycles

This work experimentally and numerically studies the behavior of concrete-filled circular steel tubular stub columns experiencing corrosion and freeze-thaw cycles. The considered parameters are the corrosion rate, freeze-thaw cycles, and the number of alternations of the corrosion and freeze-thaw cycles. The failure modes and axial load-displacement curves are measured and discussed. The experimental results show that all the columns exhibit shear failure, and the core concrete suffers severe damage as the corrosion rate increases. The residual bearing capacity and ductility coefficient decrease with an increase in the corrosion rate and freeze-thaw cycles. A finite element (FE) model is also developed using the material thickness and strength reduction analysis method and validated using the experiments in this study. Further, a parametric analysis is conducted to identify the influences of the critical parameters on the load-bearing capacity of the columns. The finite element model results demonstrate that exposure to the alternations of corrosion and freeze-thaw cycles significantly influences the residual bearing capacity of the columns: the higher the number of alternations of corrosion and freeze-thaw cycles, the lower the residual bearing capacity of the columns. Finally, a simplified method is proposed for predicting the ultimate bearing capacity of concrete-filled circular steel tubular stub columns exposed to corrosion and freeze-thaw cycles.