Axisymmetric simulation of circular concrete-filled double-skin steel tubular short columns incorporating outer stainless-steel tube

A concrete-filled double-skin steel tubular (CFDST) column incorporating an outer stainless-steel tube and a high-strength inner carbon steel tube exhibits high corrosion resistance and load-carrying capacity. This paper presents the axisymmetric analysis technique for simulating the structural response of short circular CFDST columns loaded concentrically. The double-skin confinement mechanism for modellinng the sandwiched concrete is explored and implemented in the analysis. The significant strain hardening response of stainless steel in axial compression is recognized in the analysis technique. The benefits of axisymmetric analysis over the full three-dimensional simulation are highlighted for the analysis of a member which is symmetric about its rotation vertical axis. The comparison of axisymmetric analysis results is made with the experimental results given in the previous independent studies. The parametric investigation on the structural response of CFDST columns is performed by means of using the verified axisymmetric model. The analysis results indicate that the inner tube diameter-to-thickness ratio less than 40 should be selected to prevent its local buckling from occurring and the inner tube should have yield stress higher than the 0.2% proof strength of the outer stainless steel tube. The outer stainless-steel with proof stress of 195 MPa should be filled with high-strength concrete of 120 MPa to ensure the strain compatibility. Liang’s design model closely estimates the ultimate axial strengths of the CFDST columns composed of an outer stainless-steel tube and a high-strength inner carbon steel tube.