Numerical modelling of concrete-filled stainless steel slender columns loaded eccentrically

Abstract

Purpose This paper is aimed at clarifying the behaviour of concrete-filled stainless steel tube (CFSST) slender columns. Based on the review of previous works, it can be found that the pieces of research on the behaviour of CFSST slender columns are very rare and the existing studies, to the author’s knowledge, have not covered this topic in greater depth. The purpose of this paper is to investigate the structural response and strength capacity of eccentric loaded long CFSST columns. Design/methodology/approach In this paper, a new finite element (FE) model is presented for predicting the nonlinear behaviour of CFSST slender columns under eccentric load. The FE model developed accounts for confinement influences of the concrete in-filled material. In addition, the initial local and overall geometric imperfections were introduced in the numerical model in addition to the inelastic response of stainless steel. The interaction between the stainless section and concrete in-filled was modelled using contact pair algorithm. The FE model was then verified against an experimental work presented in the literature. The ultimate strengths, axial load–lateral displacement and failure mode of CFSST slender columns predicted by the FE model were validated against corresponding experimental results. Findings The simulation results show that the improvement in the column strengths (compared to hollow section) is less significant when the composite columns have small width-to-thickness ratio. Finally, comparisons were made between the results obtained from FE simulation and those computed from the Eurocode 4 (EC4). It has been found that the EC4 predictions in most analysed cases are conservative for composite columns analysed under a combination of axial load and uniaxial or biaxial bending. However, the conservatism of the code is reduced with a higher slenderness ratio of the composite columns. Practical implications The simulation results throughout this research were compared with the corresponding Eurocode predictions. Originality/value This paper provides new findings about the structural behaviour of CFSST columns.