Behavior of circular CFST stub columns under sustained load and chloride corrosion

This paper studies the behavior of circular concrete filled steel tubular (CFST) stub columns under sustained load and chloride corrosion. A total of 17 specimens, including 11 stub CFST columns and 6 reference hollow steel tubes, were tested. The main parameters are loading ratios (0, 0.3 and 0.6) and corrosion conditions (no-corrosion, fully-immersed and half-immersed in corrosion environment). It was found that corrosion could have significant influence on the ultimate strength of both CFST and hollow steel tubular stub columns. Compared with the hollow steel tubes, the composite actions in CFST specimens can effectively lighten the effect. A finite element analysis (FEA) model was developed to take out full-range analysis on the behavior of CFST stub columns under long-term loading and corrosion, including failure modes, load-displacement relationship, load distribution in the composite section, and the interaction between the steel tube and its core concrete. Parametric studies were carried out to study the main factors that may influence the residual axial strength of CFST stub columns under long-term loading and corrosion. Based on the parametric analysis, a simplified model for the residual axial strength ratio of CFST stub column was suggested.