Study On Seismic Behavior Of Reinforced Joints In The Joint Area Of Square Steel Tubular Column-H-shaped Steel Beam

Steel structure has the characteristics of high strength,fast construction,low construction noise,good toughness and excellent seismic performance.Because of the high cost of steel structure,there is no large area of steel structure used in building structure at present in China.However,with the demolition and reconstruction of concrete structure,it is found that construction waste is not easy to deal with after the demolition of concrete,while steel can be reused.Nowadays,with the development of green building advocated by our country,the steel structure has received unprecedented attention,and the joint is the most important part of the steel structure research,so it is very meaningful to study the steel structure in this paper.In this paper,combined with the current research status and the requirements of relevant codes,the strengthened beam column joints in this joint area are designed.The construction of this node is divided into two steps,factory welding and field bolt connection.The assembly type installation method provides sufficient guarantee for the construction quality of the node.The seismic performance of the designed joint needs to be studied.Because the test is relatively affected by external factors and the cost is high,this paper studies and analyzes the seismic performance through the finite element software ABAQUS.Through the analysis results of the finite element software,the important parameters of the node are obtained,and the theoretical calculation formula of the bearing capacity applicable to the node is deduced.At the same time,the corresponding suggestions are put forward for the construction of the node,which provides the basis for the actual construction.The main research contents and results are as follows:1.In this paper,a reinforced beam column joint in the joint domain is proposed.Combined with the research status at home and abroad and relevant design specifications,the specific size parameters,material selection and specific construction and installation steps of this joint are given,which enriches the types of steel structure joints.After the Northridge earthquake in the United States and the Kobe earthquake in Japan,it is found that although the stiffness of semi-rigid joints is not as large as that of rigid joints,the brittle failure of semi-rigid joints rarely occurs.The nodes are classified by the calculation of the initial bending stiffness.The initial stiffness value of this node is1.11?10~4kN?m/rad,so this node is semi-rigid;2.The checking calculation of joint design formula mainly considers the bearing capacity and structural requirements from the aspects of weld checking,bolt checking and strong column weak beam,which provides the corresponding theoretical basis for the design of this joint;3.The finite element analysis of the joint is carried out by ABAQUS.Because there is no relevant experimental study to do comparative analysis in this paper,and there are many parameters selected by ABAQUS,so the feasibility of the selection of finite element parameters is first confirmed by verification simulation,then through the finite element analysis,the stress and deformation diagrams of each component of base node in different stages are obtained,and the stress mechanism and failure characteristics of the node are analyzed;4.In this paper,through the finite element software,the antisymmetric displacement control load is applied on both sides of the beam end to carry out the quasi-static simulation.The influence of the parameters on the hysteresis curves,skeleton curves,ductility,energy dissipation and stiffness degradation of the joints were studied by changing the thickness of the plate,the pretightening force of the bolts,the friction coefficient between the components,the opening size and spacing of the webs.Thus,the influence of the variable parameters on the seismic performance of the joint is evaluated.The results show:Under the premise of satisfying the strength of the joint,changing the pretightening force of the joint bolt or the friction coefficient of the contact surface has little effect on the seismic performance of the joint;The initial stiffness of the joint can be increased by having an inner partition in the column,but the hysteresis curve without the inner partition is fuller than that with the inner partition;The ultimate bearing capacity of the joint will be reduced to a certain extent but the ductility of the joint will be improved;5.According to the actual situation,the corresponding node construction scheme is provided,which provides a certain basis and guarantee for the construction and installation of the node.This paper combines finite element numerical simulation software and theoretical analysis,by comparing the numerical size of each index,thus the influence of the variable parameters on the seismic performance of the joint is evaluated.At the same time,the corresponding construction suggestions are given,which lays the foundation for the subsequent application of this node project.