Trussed square concrete-filled steel tubular hybrid structures subjected to axial compression

Abstract

This paper introduced the mechanical performance of trussed square concrete-filled steel tubular (CFST) hybrid structure subjected to axial compression. A refined finite element analysis (FEA) modelling was established and verified against the experimental results. Based on the FEA modelling, the hybrid effect and the working mechanism of the structure were revealed through the comprehensive analysis of the internal force distribution, the axial compression force (N) versus average longitudinal strain (ε) relation, the typical failure modes, and the stress distribution. The N-ε relation was classified into five types according to the failure modes and critical factors elucidated. The criterion for determining the ultimate limit state of the trussed square CFST hybrid structure was established by investigating its load-bearing capacity and peak strain. An interface contact stress model was proposed to describe the hybrid effect of the structure. Based on parametric analysis, critical parameters used to characterize the hybrid effect were identified, thereby the equivalent slenderness ratio for straight trussed CFST hybrid structure and that for a curved one considering the influence of the initial curvature ratio were proposed. The quantitative relationships between the stability factor and equivalent slenderness ratio were established and validated so as to facilitate the calculation of the load-bearing capacity for both straight and curved trussed square CFST hybrid structures.