Bending behavior and design of tapered lightweight CFDSST with large hollow ratio

Given the tremendous potential of tapered lightweight concrete-filled double-skin stiffened steel tubular members with large hollow ratio in engineering structures, such as building structures and wind turbine tower, the bending behavior of these members, distinguished by their large hollow ratio, lightweight concrete fill, and longitudinal stiffeners, was the focus of this study. Eleven specimens were tested under four-point bending loading. The failure modes, deflection curve distributions, moment-deflection curves, and strain development of specimens were discussed. The results indicate that the maximum deformation of the specimens is located near the smaller section in the constant moment region. Cracking was observed in the tension side concrete, and the outer edge of the compression side concrete was crushed. The validated finite element model was used for mechanical analysis and parametric study, where the stress development process in the member and the influence of parameters such as hollow ratio, steel tube diameter-to-thickness ratio, material strength, and tapered angle on the bending strength of the member were explained and discussed. Based on the results of experimental and numerical analyses, a novel method for predicting the bending strength was proposed. This method was shown to accurately predict the bending strength of concrete-filled double-skin steel tubular members.