Eccentric compression test and ultimate load strength analysis of circular CFST long column with local corrosion

During the service period, the load bearing capacity of circular concrete filled steel tubular (CFST) structures decreases over time under harsh corrosive environment, seriously threatening to the structural safety. In this paper, an artificial machining defect was introduced to simulate a local circumferentia-through corrosion on the exterior surface of steel tube, and thus 45 CFST long columns with local corrosion of a moderate slenderness ratio were tested by varying corrosion position, degree of corrosion volume loss (DoV), degree of corrosion surface area loss (DoA) and degree of corrosion wall-thickness loss (DoT). Their impacts on the axial bearing capacity, stiffness and ductility were discussed. The research results reveal that all failure modes for the specimens display feature of global compression-bending failure with local outward buckling; with increasing the DoV, the bearing capacity, stiffness and ductility of CFST specimen with local corrosion declines to different extents; as for the effect of local corrosion position, the largest one occurs while the corrosion is located at the mid-length of specimen; Ranking the effect of corrosion parameters on the compression-bending performance, the largest one is the DoV, then the second the DoT and the minimum the DoA. For the local circumferentia-through corrosion, very small effect of the DoA is actually observed. A simplified practical prediction model was established for the compression-bending bearing capacity of locally corroded CFST columns, which can provide a reference framework for their life-cycle design.