Research On Seismic Performance Of Multi-layer Rigid-connected Eccentrically Braced Frame

Eccentrically Braced Steel Frames(EBF)have the advantages of high stiffness of concentrically braced steel frame and good ductility of pure steel frame.The link beam of the eccentrically braced steel frame is the most important component,which determines the seismic performance of the structure.The eccentrically braced steel frame can reduce the lateral displacement of the structure.The first yield and bending deformation of the link beam section can play a protective role.In this paper,the eccentrically braced steel frame is studied in combination with experiments and finite element simulation analysis,and the stress,deformation characteristics and seismic performance of the eccentrically braced steel frame are analyzed.The main work and achievements are as follows:(1)The reciprocating loading test of the eccentrically braced steel frame was carried out.The test results show that the eccentrically braced steel frame is dominated by the shear deformation of link beam section,and all components except the link beam section were kept intact.The deformation degree of the link beam section from the top layer is gradually weakened,and finally it was broken at the web of the link beam section of the third layer.The eccentrically braced steel frame has good hysteresis and energy consumption capabilities.(2)The eccentrically braced steel frame model was established through ABAQUS software,which was simulated and analyzed,and the finite element analysis results were compared with the test results to verify the validity of the model settings.A set of finite element models are simulated and analyzed using the same settings.From the analysis results,it can be seen that the length of the link beam section and the spacing of the ribs have a greater impact on the mechanical performance of the eccentrically braced steel frame.(3)Under the same length of link beam section,the spacing of ribs is changed to establish a set of models and perform finite element simulation.The ultimate bearing capacity of the eccentrically braced steel frame is greatly affected by the number of link beam ribs.As the number of rib increases,the ultimate bearing capacity,hysteretic performance,energy dissipation capacity and ductility of the eccentrically braced steel frame are significantly enhanced.The stiffness degradation of eccentrically braced steel frames increases with the number of ribs..(4)The link beam section adopts the same rib spacing,and the length of the link beam section is changed to establish a set of models for finite element simulation analysis.It can be seen that when the length of the link beam section is small,the shear deformation and broken of the eccentrically braced steel frame occurs;when the length of the link beam section is large,the bend deformation and broken of the eccentrically braced steel frame occurs.The elastic stage of the eccentrically braced steel frame is affected by the length.As the length increases,the yield displacement gradually increases,and the horizontal load reaching the yield state gradually decreases.As the length of the link beam decreases,the ultimate bearing capacity,hysteretic performance,energy dissipation capacity,ductility,initial stiffness and stiffness degradation of the eccentrically braced steel frame have been significantly enhanced.