Dynamic responses of hybrid FRP-concrete-steel double-skin tubular column (DSTC) under lateral impact

Hybrid fibre-reinforced polymer (FRP)-concrete-steel double-skin tubular column (DSTC) is a new form of composite column that consists of an outer FRP tube and an inner steel tube, with the space between them filled with concrete. Although many studies have been conducted on the hybrid DSTC, studies on its lateral impact behaviour are very limited. This study numerically investigates the dynamic responses of hybrid DSTC under lateral impact. Numerical models of the hybrid DSTCs were developed and validated with existing test results. Afterwards, the dynamic responses, including the deflection-time histories and the force–time histories, were analysed. Specifically, the bending moment and shear force distributions at typical cross sections were discussed, and the impact resistance (shear and flexure) from each component (FRP tube, concrete, and steel tube) was investigated. The results indicate that the hybrid DSTC exhibits ductile behaviour under lateral impact. Even though the FRP tube cannot contribute to the impact resistance directly, it can greatly improve the impact resistance of the concrete. Moreover, parametric analyses were conducted to investigate the influences of different parameters on the lateral impact resistance of hybrid DSTC. Finally, simplified design-oriented equations were developed to predict the dynamic flexural capacity of hybrid DSTC.