Research On Seismic Behavior Of Core Concrete-Filled Steel Tube Joints And Frame Of T-section Special-shaped Column

As a new type of composite structure,the special-shaped columns composed of core concrete-filled steel tube combine the advantages of concrete-filled steel tube column and special-shaped column,it can not only increase the actual usable floor area of the room,but also has good ductility and high bearing capacity.The core concrete is in three-dimensional confining pressure state,which effectively restrained the lateral deformation;in turn,steel pipe under internal and external concrete compression buckling instability are avoided.The advantages of the special-shaped concrete-filled steel tube core columns make it has a broad prospects for development in underground structures,super high-rise and bridges structure.As the transmission of structural system,joints have a complex function of bearing axial force,shear force and bending moment,so the spatial joints show more complex mechanical properties.At present,the research on space joint of the special-shaped concrete-filled steel tube core columns is relatively less,which hinders its application and popularization in engineering.Based on the above situation,the analysis on seismic performance of this new spatial composite joints has an important reference value for further theoretical research and engineering application.In this paper,the author studies the seismic behavior of the joints and structure of T-section concrete filled steel tube core column by using ABAQUS and Midas/GEN software.The main contents of this paper include the following aspects:(1)Based on the characteristics of the whole process simulation of ABAQUS finite element analysis and the existing literature to establish models.Reasonable selection of material characteristics,the definition of contact relationships and meshing,verify the correctness and rationality of the modeling;this paper established joints of T-section column composed of core concrete-filled steel tube and steel beam under cyclic loading,comprehensively analyzed the mechanism and characteristics of the joints from the initial stress to the final failure.(2)According to the above modeling method,finite element simulation software is used to analyze the influence of the axial compression ratio,the thickness of the steel beam web,the thickness of the steel tube wall,the core concrete strength and the location on the joints.The author has an analysis of the joint through the stress nephogram and to carry on the discussion about load displacement curve,skeleton curve,ductility,strength degradation,stiffness degradation and energy dissipation capacity,and to comprehensively evaluate the seismic performance of the joints.(3)By using the finite element analysis software Midas/GEN,the author established the special-shaped columns composed of core concrete-filled steel tube frame structure model and the structure of static elastic plasticity under rare earthquake analysis Push-over.Acquired by the performance point and the layer displacement angle,the layer displacement,the layer shear force at the performance point,the development situation of plastic hinge in order to evaluate comprehensively the seismic performance of the structural model.The results show that meets the specification limit.The plastic hinge in compliance with requirements,such steel reinforced concrete special-shaped column frame system showed good seismic performance under earthquake.