Performance evaluation of light-gauge CFST columns incorporating expansive self-compacting concrete

This study conducts an extensive analysis of the axial compressive performance of rectangular light-gauge steel tube columns filled with expansive self-compacting concrete (ESCC). Thirty-six concrete-filled steel tube (CFST) samples, comprising conventional self-compacting concrete (SCC) and type K expansive cement-based SCC, as well as six hollow control samples, were subjected to monotonic axial loading tests. The experimental program included modifications in steel tube thickness (2 mm, 3 mm, and 4 mm), concrete grade (M30, M40, and M50), and column slenderness ratio to evaluate their impact on structural performance. The use of expansive agents successfully generated self-stress in the concrete core, hence improving the interaction among steel and concrete composites, as validated by strain measurements and analytical models. The ESCC-filled columns demonstrated enhanced confinement effects, delayed the initiation of local buckling,and significant improvements in load-bearing capability, resulting in strength increases of up to 21% compared with their SCC-filled equivalents. Finite element models created in ABAQUS precisely mirrored the experimental behaviour, with prediction discrepancies confined to a 10% margin. Additionally, a revised theoretical model adjusted to incorporate self-stress and confinement effects exhibited a robust association with the empirical results. The performance metrics, including strength enhancement, confinement efficiency, ductility, and concrete contribution, validate the efficiency of expansive self-compacting concrete in refining the structural integrity of CFST columns. The results highlight the promise of expansive self-compacting concrete as a pivotal material innovation for enhancing the reliability and load-bearing capacity of light-gauge steel-concrete composite columns.