Non-linear Finite Element Simulation of Rectangular Hybrid FRP-Concrete-Steel Double-Skin Tubular Columns Under Axial Compression

This chapter delves into the non-linear finite element simulation of rectangular hybrid FRP-concrete-steel double-skin tubular columns (DSTCs) under axial compression. The study focuses on four key areas: the effect of outer FRP tube aspect ratio, the influence of outer FRP tube thickness, the impact of inner steel tube thickness, and the role of concrete-filling inside the inner steel tube. Through extensive numerical simulations, the research reveals that increasing the aspect ratio of the outer FRP tube leads to higher axial strains in confined concrete, while the axial stress does not exhibit a uniform increment. The study also finds that varying the thickness of the outer FRP tube has a marginal effect on the behavior of the DSTCs, but it does increase both axial stress and strain of confined concrete. Notably, the inner steel tube thickness demonstrates significant changes in both axial stress and strain, highlighting its substantial influence on the structural performance. Additionally, the research shows that concrete-filled specimens exhibit notably higher axial stresses compared to hollow ones, although this comes with a slight reduction in axial strain. The conclusions drawn from this study emphasize the potential to optimize design parameters for enhancing the axial load-bearing capacity of hybrid rectangular DSTCs, considering the trade-offs between axial stress and strain of confined concrete.