Nonlinear Finite Element Analysis On Square Concrete-Filled Steel Tube Column Under Axial Loading

The concrete-filled steel tubular structures have a lot of advantages, such as high strength, light quantity, good shape, fast tiredness, fast strike and so on. At present they have been used in many high-buildings. In contrast, relatively few researchers have investigated theoretically and experimentally the performance of square concrete-filled steel tubular structures. The design method of these structures is not mature, either. Therefore, it is necessary to make further researches on the finite element model and design method.Based on ago study results, this paper has carried out the research on behaviour and simplified calculation methods and stress-strain curves for steel tube and core concrete of square concrete-filled steel tube members subjected to axial loading conditions. The main achievements can be summarized as follows:(1)A 3-D nonlinear finite element model is developed in the paper. The constitutive model of steel tube and core concrete of concrete-filled steel tube is selected. The core concrete is modeled using concrete damaged plasticity model. The steel tube is modeled using plasticity modeled which is isotropic elasticity and plasticity model with a Von Mises yield surface. In the model, the effect of the bond between steel tube and concrete was considered.(2)Concrete-filled steel tube under axial compression is obtained by ABAQUS, which is an common analysis software by finite element method. Mechanisms of concrete-filled steel tube subjected axial loading conditions are analyzed based on the numerical method. And then steel and concrete of stress-strain curves for steel tube and core concrete were investigated systemically.(3)Concrete of stress-strain curves for core concrete is investigated and analysis concrete strength and width to thickness ratio. Based on a wide scope parametric analysis, simplified calculation methods for stress-strain curves of core concrete of concrete-filled steel tube under axial compression is proposed, which may be referred for seismic design.