Finite Element Analysis Of Concrete Filled Steel Columns Considering The Variation Of Poisson's Ratio And Elastic Modulus

The concrete filled steel tube(CFT) structure can enhance the performance of concrete and steel tube depending on the interaction of two kinds of materials under load. It has many excellent characteristics such as high bearing force, good anti-seismic performance and convenient construction, so it has already been used widely in the engineering practice. Because finite element analysis can save a lot of manpower and financial resources, and can provide a lot of feedback structure, the Finite Element Analysis (FEA) of CFT structures is becoming increasingly important.Firstly the analysis of finite element approaches and ANSYS software is given. ANSYS software introduction includes linear analysis, non-analysis, and the flow control of APDL. This thesis presents the research situation of CFT structures in the world, analyzes the mechanical performance of steel and core concrete and the constitutive relation of them, analyzes the variation of Poisson's ratio in elastic-plasticity stage. Then the modified elastic modulus is inducted to research the increase in bearing capacity of circular CFT structures. Based on ANSYS software, considering material non-linear and geometry non-linear question, using modified elastic modulus and the variation of Poisson's ratio, adopting APDL order flow, the test course of CFT columns is simulated through reasonable modeling, dividing mesh, and suitable loading method. At last, the limited bearing capacity and the load-strain relationship curves of CFT structures can be obtained.The results show that the limited bearing capacity of specimens considering Poisson's ratio variation is higher than that of specimens without considering Poisson's ratio variation. The limited bearing capacity of specimens by using of modified elastic modulus is higher than experimental value. In all, calculating results are in good agreement with experimental results. The finite element analysis course shows the loading situation and mechanical behavior of CFT structures. Further research on mechanical characteristics and mechanism of CFT structures can be done by FEM analysis.