Numerical analysis of circular tubed high-strength concrete columns with embedded steel tubes under axial compression

Abstract

This paper presents an in-depth investigation into the compressive behavior of the circular tubed high-strength concrete with embedded steel tubes (THSC-ST) columns using a finite element (FE) approach. The composite action of the columns is comprehensively explored. It can be detected from the numerical results that the confinement provided by the external steel tube in the THSC-ST column is significantly enhanced since the external steel tube does not carry the axial load directly. Besides, increasing the diameter of the internal steel tube can effectively improve the axial stress of confined concrete. Moreover, more effective confining stress of the external tube is observed after wrapping FRP jackets, leading to stiffer the post-peak behaviors for the core and sandwich concrete simultaneously. An extensive parametric analysis is also performed based on the validated FE model to explore the effects of the internal steel tube location, the number of FRP layers, the thickness and yield strength of the steel tube, and concrete compressive strength on the structural behaviors of the THSC-ST columns. Finally, a new formula is proposed to estimate the axial load capacity of the THSC-ST columns and high predicted accuracy is found by the comparisons between the theoretical and experimental results.