Axial Compression Behavior and Failure Mechanism of Aluminum Alloy Tube–Concrete Long Columns: A Finite Element Study

Aluminum alloy tube–concrete composite columns have received increasing attention owing to their high strength-to-weight ratio and superior corrosion resistance compared with conventional steel–concrete composite columns. In this study, a refined finite element model is established to investigate the axial compression behavior of aluminum alloy tube–concrete long columns. The results indicate that the axial bearing capacity and deformation characteristics are strongly governed by the confinement effect provided by the aluminum alloy tube, which varies significantly with different cross-sectional configurations. Circular and square aluminum alloy tubes exhibit distinct confinement mechanisms, leading to different stress distributions and damage evolution patterns in the core concrete. Enhanced confinement effectively improves the utilization of concrete strength and delays local buckling of the aluminum alloy tube, thereby contributing to an increase in axial bearing capacity. Furthermore, parametric analyses clarify the combined influence of material properties and geometric parameters on the confinement efficiency and overall axial compression performance of the composite columns.