Experimental Study on the Eccentric Compression Behavior of Stiffened Alkali-Activated Concrete-Filled Steel Tube Short Columns

To enhance the environmental sustainability and structural performance of concrete-filled steel tubes (CFSTs), this study experimentally investigates the eccentric compression behavior of short CFST columns incorporating alkali-activated concrete (AAC) and internal stiffeners. Fifteen specimens were tested, varying in steel tube thickness, stiffener thickness, and eccentricity. The results show that increasing eccentricity reduces load-bearing capacity and stiffness, while stiffeners delay local buckling and improve stability. Based on the experimental findings, the applicability of the GB 50936-2014, Design of Steel and Composite Structures Specification, and the American AISC-LRFD specification to the design of ACFST columns is further evaluated. Corresponding design recommendations are proposed, and a regression-based predictive model for eccentric bearing capacity is developed, showing good agreement with the test results, with prediction errors within 10%.providing technical references for the development of low-carbon, high-performance CFST members.