Study On Seismic Behavior Of Sliding System Bridges With Plate Rubber Bearing

The plate rubber bearing is widely used in medium and small span highway girder bridges in China because of its good seismic performance.In order to facilitate construction and installation,the plate rubber bearing is usually used in the way of no connection,and is directly used in the cushion stone of the pier top or the cover beam.Based on the structure form of this type of bridge with rubber bearing plate,the seismic damage of the bridge with rubber bearing plate in Wenchuan earthquake is mainly caused by the displacement of main girder,the damage of bearing and retaining block,and the seismic damage rate of the bridge pier is low.To adopt the earthquake damage mechanism of the small and medium-sized span highway bridge plate rubber support and different mechanical properties of the influence of parameters on the seismic performance of Bridges under seismic action,relying on the bridge as an example,the whole bridge finite element calculation model is set up,using nonlinear time history analysis method,the plate rubber bearing as a weak link,under the condition of the priority to be destroyed in the earthquake,The seismic performance of plate rubber bearing bridge is systematically studied.The main research contents and conclusions are as follows:1.The characteristics and mechanical performance of the plate rubber bearing are summarized and analyzed.It is a kind of bearing type with good seismic performance and reasonable economy.The reasons for the low seismic damage rate of bridge piers in Wenchuan earthquake are analyzed,and the distribution law of seismic damage and bridge structural system is revealed.Under the action of earthquake,the bridge with sliding bridge structure system of plate rubber bearing slips through the friction of the bearing,and the bearing failure yields to interrupt the force transmission path,which reduces the seismic force transmitted to the substructure,and reaches the function of seismic isolation energy dissipation to a certain extent.2.Based on the seismic system of Bridges,the structural characteristics of sliding system with plate rubber bearing are analyzed.It is not a complete seismic isolation system,but a quasi-seismic isolation system.For the simulation of the finite element calculation model of the slab rubber bearing bridge under this system,the accuracy of the structural stiffness simulation,the accuracy and accuracy of the simulation under the boundary conditions and the mass distribution of the structure should be fully considered in the establishment of the model.3 Based on the dynamic incremental nonlinear time history analysis method,was studied under the action of earthquake,the ductility seismic design system,the vibration isolation design system and the seismic performance of the bridge must reduce isolation system,through the analysis of the seismic response of bridge components,verify the considering friction and sliding plate rubber bearing has better seismic performance.4.Based on the nonlinear time-history analysis method,this paper analyzes the seismic response of the bridge structure by changing the relevant structural parameters of continuous girder bridge and simply supported girder bridge,and obtain the deformation of plate rubber bearing,top displacement of main girder pier,internal force of bridge pier,collision of retaining block and abusement under different earthquake action.According to the law of seismic response of bridge structure to the change of relevant parameters,the reasonable value range of relevant parameters is determined.5.Based on the analysis of the results of finite element numerical models of continuous girder Bridges and simply supported girder Bridges,it can be seen that the seismic response of their bridge structures under the action of earthquakes is generally similar,but due to their different structural forms,there are also the following differences.Under the action of longitudinal earthquake,simply supported beam is easy to produce large longitudinal displacement of main beam,while for continuous beam,the impact force between main beam and abutment is larger than that of simply supported beam.Under the seismic action of the transverse bridge,the retaining block has an obvious limiting effect on the main girder.For continuous girder and simply supported girder bridge,the retaining block and anti-falling girder device with sufficient strength should be set to avoid the risk of falling girder caused by the excessive displacement of the main girder.