Behaviour of FRP-rubber concrete-steel double-skin tubular slender columns under eccentric compression: An experimental and theoretical study

FRP-Rubber Concrete-Steel Double-Skin Tubular Columns (RC-DSTCs) is an innovative green composite structure that not only mitigates the environmental impact of waste rubber by promoting its recycling but also enhances ductility through the high toughness of rubber concrete. Previous research on RC-DSTCs primarily focused on the axial compressive performance of stub columns, with few studies addressing the behaviour of slender RC-DSTCs. This study focused on the eccentric compressive behaviour of RC-DSTCs, investigating the effects of load eccentricity (0, 25, 50, and 75 mm), rubber volume replacement rate (0 %, 5 %, and 10 %), GFRP tube thickness (2, 4, and 6 mm), and slenderness ratio (20.08, 26.78, and 33.47) on their performance under eccentric compression. The experimental results indicated that as the load eccentricity and slenderness ratio increased, the failure mode of RC-DSTCs changed from compression-dominated material failure to bending-dominated stability failure, accompanied by a reduction in axial stiffness and peak load. Increasing the rubber volume replacement rate reduced the axial stiffness and peak load of RC-DSTCs but significantly enhanced their ductility. As the rubber volume replacement rate increased from 0 % to 5 % and 10 %, the ductility of RC-DSTCs improved by 2 % and 38 %, respectively. Similarly, increasing the GFRP tube thickness effectively improved the ductility of RC-DSTCs, although it had a limited effect on improving the peak load. The experimental capacities of RC-DSTCs aligned well with the predicted capacities, providing a reference for future research and engineering applications.