Influence Of Rubber Buffers On Transverse Vulnerability Of Isolated Continuous Girder Bridge

Side retainers play an important role in bridge isolation system,which mainly manifested in restricting the displacement of girders and preventing it from girder falling.However,seismic mitigation and isolation techniques are widely used in bridges built recently and the relative larger displacements of them cause the impact with side retainers or even girder falling.In order to evaluate how side retainers would influence isolated continuous girder bridges and how rubber blocks would reduce this influence,following researches are conducted in this paper:(1)Shape factor,volume,rubber material and shape are selected as controlled variables in experiment design,which aims to find out the relationship between buffering capacity of rubber blocks and aforementioned variables.And a new rubber constitutive model would be proposed based on experiment results.The result indicates that constitutive models of rubber blocks with same material do not vary with impact power or block volume.It is related with shape factors.The smaller the shape factors are,the better the buffering effects are.And there is a limit on this effect that when shape factors are smaller than 0.25-0.28,the buffering effects would not become better;(2)A specific isolated continuous bridge in western China is chosen as research object to construct a finite element model of it and run nonlinear analysis on this model.Vulnerability analysis is carried out and shows that the existence of side retainers would reduce the deformation of isolation bearing with the growth of girder acceleration,which means suitable distance between side retainers and girder could make full use of the damping effect with bearings’ isolation capacity retained.(3)A new rubber block designing method is proposed based on the transverse pounding force of a bridge and this method is used to design buffering rubber blocks for the bridge mentioned in chapter2.And vulnerability analysis is carried out on the results.It shows that rubber block could reduce the pounding force and displacement during earthquake,but to maximize this effect,a suitable combination of primary interstice and rubber block thickness must be found out.