Research On The Influence Of Fault Distance On Seismic Vulnerability Of Continuous Rigid Frame Bridge

There are many mountains in the western region,and when the highway bridges cross the deep valleys of the mountains,the form of long-span continuous rigid frame bridges is often used.Therefore,it is of great significance to analyze the seismic vulnerability of long-span continuous rigid frame bridges and promote the seismic performance evaluation of such bridges.Considering the impact of earthquakes of the different fault distance and the external shear keys on the bridges,this paper will take a continuous rigid frame bridge as an example to systematically study its seismic vulnerability.The paper mainly concludes the following aspects:1.The theory and method of vulnerability analysis in China and abroad are introduced in this paper.And the shortcomings of current seismic vulnerability research of long-span continuous rigid frame bridges are analyzed.2.This paper introduces the way to simulating of the main components of the bridge including the main beam,the support and the pier by OPENSees.The contact element is established from the aspect of the failure mechanism of the external shear keys,according to the actual situation of the collision between the bridge beam and the external shear keys.There are many ground motions from the PEER database and ground motions of Wenchuan earthquake to be elected as the inpuuting ground motions of the seismic vulnerability analysis of long-span continuous rigid frame bridges.3.The basic steps of seismic vulnerability analysis suitable for this paper are established,and according to the existing research results,the damage indexes of bridge pier bending failure,shear failure and bearing deformation failure are established.4.The vulnerable positions of each bridge pier are found under the action of longitudinal and transverse earthquake.The nonlinear time-history analysis method based on incremental dynamic analysis(IDA)is used to analyze the response of the bridge,then the vulnerable positions of the bridge piers under the action of longitudinal and transverse earthquakes with the different fault distance are studied,and the cloud maps of vulnerable components are drawed.Combined with the attenuation of the ground peak acceleration of the selected seismic wave,the seismic wave in each fault interval is adjusted to a specific intensity of ground motion,then the vulnerability probability of the bottom sections and top sections of each pier under the action of the longitudinal earthquake are compared and the vulnerability probability of each vulnerable component under the action of longitudinal and transverse earthquake is compared.5.The seismic fragility analysis of the long-span continuous rigid frame bridge considering the external shear keys is carried out under the action of diffetent fault distance,and the influence of the external shear keys on the vulnerable order of the vulnerable components of the bridge and the magnitude of the vulnerability probability of each vulnerable component of the bridge are analyzed.