Numerical investigation on the performance of concrete-filled double-skin steel tubular members under tension

• We developed a numerical model for CFDST members under tension.
• We assessed the steel–concrete composite action for CFDST tensile members.
• We suggested a design equation for the ultimate tensile strength of CFDST members.

This paper presents a numerical investigation on the tensile behaviour of concrete-filled double-skin steel tubular (CFDST) member. A comprehensive finite element (FE) model is established and calibrated against the test results for the CFDST members under concentric and eccentric tension. The comparison shows that the proposed FE model is capable to capture the structural behaviour of the tensile specimens. Parametric studies are then conducted to investigate the influence of some key parameters, such as the material strength, the nominal steel ratio and the hollow ratio on the tensile behaviour of composite members. The steel–concrete composite action, the effect of loading paths and the tension–bending interaction diaphragm are also discussed. It is found that the tensile strength of the member depends on the composite action between steel tubes and sandwich concrete, and the tension–bending interaction diaphragm can be represented by a simple linear relationship. Finally, the design equation to predict the tensile strength of CFDST member is proposed, and the comparison results show that the proposed equation has a good accuracy.