Finite Element Analysis On Mechanical Behavior Of Joint Of High Strength Concrete-Filled Square Steel Tube With Inner CFRP Circular Tube

In recent years, with the maturity of the theory of concrete filled steel tube, CFT has been widely used in engineering. Concrete filled steel tubular structure has many features, such as high strength, good ductility, high fire resistance,and excellent seismic performances, among them, the joint of concrete filled square steel tube, compared with the joint of concrete filled circular steel tube structure has the advantages of simple structure and convenient construction. Therefore, concrete filled square steel tube attracts much attention, and has been applied more and more in high-rise buildings. For the study of the joint of concrete filled square steel tube focused on the study of ordinary concrete filled steel tube for high strength concrete are not many theoretical studies, especially through the built-in CFRP to solve the problem of insufficient constraints on the foot of concrete is also more less. This paper through the finite element analysis method, researches the mechanical properties of the joint of high strength concrete filled square steel tube that built-in CFRP under cyclic loading, the seismic performance and the performance of hysteresis.In this paper, the nonlinear finite element program Abaqus/Standard is conducted to simulate the mechanical properties of the joint of high strength concrete filled square steel tube and the mechanical properties of the joint of high strength concrete filled square steel tube that built-in CFRP under monotonic loading and cyclic loading, conduct analysis and research. This article has carried on the discussion to the model establishment method and the material this construction relations' selection, the whole process of the joint, the stress distribution of the square steel tube; the I-beam; the high strength concrete; the CFRP circular pipe are discussed, to select the appropriate unit type, material model and failure criterion. Material parameters are from the measured, through reasonable modeling, reasonable parameter establishment, effective meshing, obtained under monotonic loading curve of load-displacement, under low cyclic loading hysteresis curve, and the skeleton curve. Analysis of the influence of the axial compression ratio, steel ratio, steel yield strength, concrete strength, CFRP configuration rate, outer plate size and other parameters on the skeleton curve. Understand the mechanical properties of the joint of high strength concrete filled square steel tube. The result indicated that this article selects the material this construction relational model, the establishment finite element analysis model, the numerical analysis method is feasible. From the simulated hysteresis curve is full, was spindle, no significant decrease in segment. Through the analysis, we can see the seismic behavior of the joint of high strength concrete filled square steel tube that built-in CFRP is similar to the joint of ordinary concrete filled square steel tube. Using the numerical analysis method, analyzes two kind of joint's work mechanisms, may provides certain reference function for present's fundamental research and the design.