Axial behavior of round‐ended section concrete‐filled steel tube columns with localized corrosion

Abstract Concrete‐filled steel tubes (CFST) columns are widely adopted in engineering applications owing to their excellent mechanical performance and convenient connection features. However, localized corrosion in the steel tubes still presents unresolved challenges regarding the performance of CFST columns, which hinders their widespread practical implementation. This paper adopted artificially notched steel tubes to simulate the local corrosion of CFST columns; a total of 19 specimens were tested to examine the impact of diverse parameters on the behavior of notched round‐ended sections concrete‐filled steel tube (RE‐CFST) columns, including the length, location, and direction of the notches. The entire loading process, failure modes, and ultimate bearing capacity were comprehensively analyzed based on the test results, which proved that the presence of notches in the steel tube significantly weakened its ability to confine the core concrete, hence reducing the ultimate load‐bearing capacity. Finite element (FE) models were developed, and the FE results aligned well with the experimental findings; then a total of 252 round‐ended columns were constructed to study the effects of three factors (notch, materials, and geometry) on the mechanical properties of CFST columns. Results illustrated the impacts of these parameters on different aspects of stub column responses with corroded steel tubes. Finally, through parametric analysis of test results, a method for calculating the ultimate axial compressive bearing capacity of the RE‐CFST column was proposed, considering the effects of the length and direction of the notch; the accuracy of this method was confirmed through comparisons with test results. The research findings provide a scientific basis for the optimization design of locally corroded CFST columns with round‐ended cross‐sections under axial compression and lay a foundation for engineering practice and the development of relevant codes.