Study On Mechanical Properties Of Separated Isolation Bearing With The C-Shaped Steel

With the emergence of more and more large-span bridges across the sea,the upper load of the bridge structure is huge,making the volume of traditional rubber isolation bearings larger and larger.The steel damper is an ideal bridge damping member for its strong hysteretic energy dissipation capability,low cost,convenient processing and installation.In recent years,it has been increasingly applied to bridge seismic isolation.Based on the high-capacity(GRB)bearing developed by our research group,this paper studies a new type of seismic isolation bearing,separated isolation bearing with the C-shaped steel.This new type of isolation bearing has the characteristics of high vertical bearing capacity,strong hysteretic energy dissipation capacity,and can respond to earthquake action in any direction.It aims to improve the falling beam of long-span continuous girder bridge during earthquake and seismic absorption of curved bridges.Firstly,the mechanical properties of C-shaped steel damper are studied by combining theoretical formula with numerical simulation.The analysis model of C-shaped steel damper is a curved beam,and the mechanical model parameters of C-shaped steel damper are deduced by using material mechanics formula.The force-displacement relationship of C-shaped steel damper is simplified to a bilinear mechanical model,and the main parameters of the bilinear mechanical model are determined.The restoring force model of C-shaped steel damper is established based on the bilinear model as the skeleton curve.ABAQUS is used for simulation analysis.On the basis of the mechanical properties of C-shaped steel damper,the mechanical properties and the bilinear model parameters of the steel damper bearing are obtained,and then the restoring force model is obtained.The isolation bearing is divided into two parts: GRB bearing and C-shaped steel damper bearing.The force-displacement curves under unidirectional and cyclic loading are studied respectively,and the restoring force model of the new bearing is obtained by superimposing the two parts.ABAQUS is used to simulate the isolation bearing.The results show that the theoretical calculation value of the isolation bearing is in good agreement with the simulation value of finite element analysis.The experimental study of separated isolation bearing with the C-shaped steel was carried out,and the vertical stiffness test,friction test and horizontal mechanical performance test were completed.The results of the vertical stiffness test show that with the increase of the vertical compressive stress,the vertical stiffness of the bearing increases rapidly and then tends to be stable.The vertical stiffness of the support after stabilization is 2690 kN/mm.The results of bearing friction test show that the sliding friction coefficient decreases with the increase of vertical compressive stress,and the sliding friction coefficient under vertical compressive stress is 0.024.The results of horizontal mechanical properties text show that the hysteretic characteristic of separated isolation bearing with the C-shaped steel is stable.With the increase of the displacement of the bearing,the equivalent damping ratio continues to increase,and the energy dissipation effect is good.