New Energy Dissipation Metal Assembly Steel Frame Beam-column Connection Joints Research On Seismic Performance

Scholars at home and abroad have found that brittle failure occurred in the traditional bolted-welded joint of steel frame beam-column after the 1994 Northridge earthquake in the United States and the 1995 Osaka-Kobe earthquake in Japan.Since then,researchers have developed various energy dissipation devices to improve the ductility and seismic performance of beam-column joints.Among them,metal connectors are increasingly used in building structures due to their advantages of high energy consumption,simple fabrication,installation and replacement,low cost,etc.Based on the existing research,this paper proposes a new type of energy-consuming metal composite steel frame beam-column connection joint,which can protect the safety of structural beams,column members and frame structures through the energy consumption and deformation of each metal connector of the joint under moderate and large earthquakes.Firstly,the mechanical properties of U-shaped metal connectors and energy dissipation metal assemblies formed by the combination of U-shaped metal connectors and soft steel plates are theoretically analyzed and the formulas of initial stiffness and bearing capacity of the connectors（assemblies）under horizontal tension and compression are derived.Using ABAQUS finite element analysis software,the finite element models of seven U-shaped metal connectors and connecting components are established on the basis of considering cross-sectional parameters,and monotonic loading analysis is carried out.The finite element analysis results are compared with the theoretical formula calculation results to prove the reliability of the formula.Secondly,the research and design of the energy-consuming metal assembly is applied to the traditional I-steel beam-column frame joint to form a new type of energy-consuming metal assembly steel frame beam-column connection joint.ABAQUS finite element analysis software is used to analyze the bearing capacity,failure mode,hysteretic performance,stiffness degradation and other properties of the new type of joint,and the influence of the changes in the geometric parameters of the cross sections of the energy-consuming metal assembly at the flange and the web U-shaped connector on the seismic performance of the new type of joint in this paper is studied.Finally,on the basis of finite element analysis,the calculation assumption is put forward,the theoretical analysis of the new type of joint studied in this paper is carried out,the calculation formula of the bearing capacity of the joint is deduced,and the design suggestions of this kind of beam-column joint are given.On this basis,the research node in this paper is optimally designed to form JD17 component,which is compared with the reference node JD1finite element analysis to verify the rationality of the design proposal.The research shows that the new type of joint can reach the seismic fortification target of the structure and better protect the main structure.The main conclusions of the research are as follows:（1）The theoretical formulas for bearing capacity and stiffness of metal energy dissipation assemblies and joints deduced in this paper have good accuracy,and their errors with finite element calculation results are all within 5%.（2）The parameters of metal connectors have a great influence on the seismic performance of the joints,and the thickness of mild steel plate has a great influence on the bearing capacity and initial stiffness of energy dissipation metal assemblies and joints.When the bearing capacity of the mild steel plate is greater than the horizontal bearing capacity of the U-shaped metal connector,the hysteretic behavior of the joint becomes worse.When the bearing capacity of the mild steel plate is less than half of that of the U-shaped metal connector,the mild steel plate will bend when it is loaded to 0.05rad;The height h of the U-shaped metal connector at the flange should be selected according to the thickness of the plate section,and h/t₁=0.5～0.8,so the hysteretic performance of the joint is better.The radius of the U-shaped metal connecting piece should not be greater than 3t₂,nor is it easy to be less than 2t₂.t₁+h of U-shaped metal connector should be close to D value,so that the aspect ratio of U-shaped section of U-shaped metal connector approaches 1,so that the failure mode,bearing capacity and hysteretic performance of the new joint are improved.（3）Under the load,the soft steel plate in the energy dissipation metal assembly firstly yields,and then the U-shaped metal connector yields and breaks.The beam and column remain intact.After the corner displacement of the joint reaches 0.04rad,the joint can be quickly repaired after the earthquake by replacing the soft steel plate and the U-shaped metal connector.