Axial compression behavior of slender concrete-filled steel tubes with machining defects representing local corrosion

This paper presents an experimental and numerical study on the axial compression performance of slender concrete-filled steel tubes with simulated local corrosion damage. A total of 11 specimens (including 8 columns with simulated local corrosion damage and 3 intact columns for comparison) were designed, constructed, and tested. The local corrosion on the steel tube was simulated by the machining defect as recommended by prior investigations. The main test parameters include the defect shape, defect sizes, and slenderness ratio. The failure modes, load-deformation curves, and ultimate resistances of the test specimens were obtained. The experimental results showed that the local defect prompted the degradation of the axial compression behavior of the specimens. Numerical models were also developed and validated by the experimental results, and used to take the randomness of local corrosion into consideration. A parametric analysis was then performed based on the validated models. In order to determine the axially compressive resistance of the slender CFSTs with local defect, the applicability of gross-section based methods provided in the design codes was first evaluated, revealing that these methods yielded unsafe-sided results. A net-section based method was therefore proposed and verified against the results from the tests and numerical study.