Compressive strength of circular aluminium alloy tube-confined concrete (ATCC) stub columns

Compared with widely studied steel tube-confined concrete (STCC) columns, aluminium alloy tube-confined concrete (ATCC) columns offer superior corrosion resistance. However, due to the lower elastic modulus of aluminium alloy, the structural behaviour and compressive strength of ATCC columns may differ considerably from those of STCC columns. To date, research on ATCC columns remains limited. This study aims to develop a predictive formula for the compressive strength of ATCC stub columns. Twelve ATCC stub columns were tested under axial compression. Their failure modes, axial load-deformation curves, and strain responses were analyzed. A validated finite element model was then established to investigate key factors influencing compressive strength. Test results show that ATCC stub columns exhibit excellent ductility. Compared with unconfined concrete, the confinement provided by the aluminium alloy tube significantly enhances compressive strength. For example, at confinement factors of 0.58 and 4.14, the compressive strength reaches 1.5 times and 6.61 times the unconfined concrete strength, respectively. Parametric analysis indicates that the diameter-to-thickness ratio, as well as the strengths of aluminium alloy and concrete, markedly affects compressive strength. A comparative analysis indicates that most existing formulas are inaccurate for predicting the compressive strength of ATCC stub columns, regardless of whether they were originally developed for STCC stub columns or previously proposed for ATCC stub columns. Finally, two formulas are recommended for predicting the compressive strength of ATCC stub columns, based on a broader parameter distribution. One is an existing formula originally developed for STCC stub columns, and the other is a new formula proposed.