Experimental studies on axial compressive bearing capacity of circular CFST stub columns with localized corrosion

During the service period, the load bearing capacity of concrete filled steel tubular(CFST) structures decreases over time under corrosive environment, seriously threatening the service performance and service life of the structures. Firstly, a turn milling machining method was used to manufacture an artificial defect to simulate a localized through-circumferential corrosion on the outer surface of steel tube. After this, axial compression load bearing capacity experiments were conducted on 45 circular CFST stub columns with localized through-circumferential corrosion by varying the corrosion position, volume loss ratio and external surface area loss ratio (area loss ratio for short, similarly hereinafter) of corroded steel tube. Secondly, the effects of localized corrosion position, volume loss ratio, area loss ratio and wall-thickness loss ratio on the axial load bearing capacity, stiffness and ductility of locally corroded CFST stub column were discussed, and the failure and load bearing capacity degradation mechanisms of the corroded specimens were revealed. Finally, a simplified practical calculation formula was established for the axial bearing capacity of CFST stub columns with localized corrosion. The results show that the corroded specimens have similar responses. Obvious outward bulging failure is predominated and occurs in the corrosion region. With increasing corrosion volume loss ratio, the bearing capacity, stiffness and ductility of the specimen with localized corrosion decrease at different level. Given the same corrosion volume loss ratio and area loss ratio, as for the impact of localized corrosion position, the largest impact appears in the specimen with localized through-circumferential corrosion at its mid-part; as for the effect of corrosion level indexes, the largest impact is that of volume loss ratio, followed by that of area loss ratio, and the minimum impact is that of wall-thickness loss ratio. The proposed prediction model can provide a reference framework for the life-cycle design of CFST columns. © 2024 Central South University of Technology. All rights reserved.