Axial compressive behavior of circular CFAT stub columns with pitting corrosion

Concrete-filled aluminum alloy tubes (CFATs) have emerged as promising alternatives to conventional concrete-filled steel tubes (CFSTs) in corrosive environments due to their superior corrosion resistance. However, once the protective aluminum oxide (Al₂O₃) film is damaged, aluminum corrosion may occur, while research on the behavior of corroded CFATs remains limited. This study investigated the axial compression behavior of circular CFAT columns with pitting corrosion. A total of nine specimens were tested, including eight corroded specimens and one uncorroded specimen. The degree of corrosion damage and the corrosion pattern were selected as key variables, and both significantly influenced the ultimate strength and failure modes of the specimens. All specimens failed within the corroded region. Specimens with uniform corrosion or random pitting corrosion exhibited a shear failure mode, whereas those with regular pitting corrosion failed along the defect alignment. A reliable stochastic modeling strategy was adopted, in which pitting corrosion was simulated using randomized geometric features. Based on the experimental and numerical results, a calculation method for predicting the ultimate strength of corroded CFAT columns was proposed based on confined concrete theory. The proposed method showed good accuracy and provides practical guidance for the design of CFATs in corrosive environments.