Vulnerability Analysis Of Curved Girder Bridge Under Bidirectional Earthquake

The performance-based seismic design method puts forward new requirements for the earthquake-resistant work of bridge structures.At the same time,while paying attention to whether the bridge collapses under strong earthquakes and loses its service function completely,It is also necessary to pay attention to the different degrees of damage that may occur before the bridge is completely destroyed,and vulnerability research is gradually becoming the main method to evaluate the seismic performance of this kind of more refined seismic performance.The curved girder bridge is an irregular bridge-span structure,and at the same time due to its wide application to the complex terrain,we can't ignore the more serious damage to the bridge in the earthquake than the regular bridge.The vulnerability analysis of the curved girder bridge at home and abroad is less,so it is of positive significance to study the vulnerability of the common curved continuous beam bridge under the action of the two-way horizontal earthquake,and can provide a reference for the seismic fortification of the complex structure.In this paper,a common small and medium span curved girder bridge is selected as an example.The main work is as follows:(1)To Summarizes the origin,development process and current situation of vulnerability research at home and abroad,and discusses the existing problems of vulnerability research.(2)To select the theoretical vulnerability method with incremental dynamic analysis as the core is selected as the calculation method of this paper,and the calculation principle of the method is described in detail.The damage index of the damage degree of the curved girder bridge can be reflected exactly and the limit value of the damage index at different levels is calculated.(3)Under the principle of calculating accuracy,10 groups of two-way real recorded waves which accord with the condition of type ? site are randomly selected,and 100 sets of bi-directional seismic waves with increasing peak acceleration are obtained by amplitude modulation.The finite element model of curved beam bridge is established,and the vulnerability curves of members under unidirectional and bi-directional seismic excitation are calculated respectively,and the aggravation degree of the failure probability of bridge under bidirectional input compared with unidirectional input is obtained.Taking the vulnerability of bridge system as an index,the paper finds out the input angle of earthquake which makes the curve bridge have the most unfavorable force and the highest probability of overall failure.(4)Buckling-restrained brace is a displacement damper widely used in building field.This device is used to achieve energy dissipation effect by yielding deformation of steel strut between curved bridge piers and beams.The common curve bridge model and the bridge model with buckling-restrained brace are established respectively.The vulnerability curves of piers and bearings are calculated and the seismic absorption and energy dissipation effect of this device on curved bridges is evaluated from the viewpoint of probability.At the same time,the high damping rubber bearing is used to compare the vulnerability of two kinds of energy dissipation devices,one is to install buckling-proof bracing and the other is to combine the two kinds of energy dissipation devices.