Research On Seismic Behavior Of New-type Energy-dissipating Self-centering Steel Structure Joint

China is a country with frequent earthquakes.The development of structural seismic technology has gone through three stages: anti-seismic stage,anti-seismic stage and isolation stage.In recent years,Professor Lu Xilin of Tongji University has put forward a new concept of seismic design of restorable functional structure,aiming at reducing the residual deformation of the building,so that the structure can be restored to normal use through a small amount of repair after rare earthquakes.Based on this design concept,a new type of joint for steel beam-column joints is proposed in this paper.The mechanical and seismic properties of this new type of joint are analyzed theoretically and by finite element method.The main research contents are as follows:(1)This paper presents and designs a new type of energy-dissipating self-centering steel structure joints.The working principle of the new type of joints is as follows: in the normal use stage and under small earthquakes,the new type of joints bear the same force as the rigid joint of ordinary steel structure,there is no rotation between beams and columns,and the joints are undamaged.Under medium and large earthquakes,the new type of joints are similar to semi-rigid joints,and the joints between beams and columns are allowed With relative rotation,energy is consumed by relative sliding friction between angle steel,friction pad and flange.After deformation,the pre-stressed steel bar provides the self-centering ability of beam-column joints,and the residual deformation after earthquake is controlled within a certain range.(2)Check the flexural and shear capacity of the new type of joints under normal service conditions,ensure that the new type of joints have sufficient flexural and shear capacity,and ensure the safety and reliability of the structure;(3)Nonlinear finite element models of energy-dissipating self-centering steel structural joints and traditional steel structural joints are established by using ABAQUS software,and their hysteresis curves,skeleton curves,stiffness degradation curves and energy dissipation coefficient curves are systematically studied,the results show that thestiffness,bearing capacity and self-resetting capacity of self-resetting steel structure joints are stronger than those of traditional steel structure joints,but the energy dissipation capacity is not as good as that of traditional steel structure joints;(4)The important factors affecting the mechanical properties of the new joint,such as the initial prestress value,the number of prestressing steel bars,the spacing of prestressing steel bars and the thickness of angle steel,are systematically studied,the results show that the bearing capacity and stiffness of the joints increase with the increase of initial prestressing force of the prestressing steel bar,the number of the prestressing steel bar,the spacing of the prestressing steel bar and the thickness of the angle steel bar.At the same time,the energy dissipation capacity decreases with the increase of the self-centering capacity.