Axial compression performance of coral concrete-filled aluminium tube (CCFAT) square stub columns

Coral materials have been used as concrete aggregate for decades to achieve self-sufficiency of materials and reduce costs of island construction. Considering the aggressive environment of islands, filling concrete into steel tube to produce coral concrete-filled steel tube (CCFST) columns is impractical. The combination of concrete and aluminium tube is proposed to avoid steel corrosion and optimize concrete performance in island construction. This study experimentally investigated the axial compression performance of nine coral concrete-filled aluminium tube (CCFAT) square stub columns. The failure mode, load-carrying capacity, and load-deformation relations were obtained, and the effects of concrete strength (fc), aluminium ratio (alpha), and confinement factor (xi) on the strength, stiffness, and ductility performance were discussed. Moreover, the adaptability of concrete-filled steel tube (CFST) design codes in the load-carrying capacity prediction of CCFAT square stub columns was assessed. The results show that the increase in alpha mostly improves the strength index (SI) and stiffness index (KI) while the effects of fc is less significant. The ductility index (DI) and composite action are closely correlated to xi. Using the design equation in AIJ code to predict the load-carrying capacity of CCFAT square stub columns is acceptable.