| Simply supported girder bridges are widely used in our country’s highway system because of its advantages of lower design and construction cost,easy construction and convenient maintenance.However,most of the simply supported girder bridges had been designed before the promulgation of the current seismic design norm,which have the potential risk of insufficient seismic performance.Therefore,the study takes the typical(20 m + 20 m + 20 m)three spans simply supported girder bridges on the trunk highway of Yunnan Province as the research object,considering the influence of pier height,establishes the sample database of the existing simply supported girder bridges,and conducts the systematic seismic performance evaluation and seismic reinforcement method research on this kind of bridge.The main contents of this paper can be summarized as follows:1.On the basis of consulting the literatures at home and abroad,this paper summarizes and analyzes the development process and research status of seismic vulnerability analysis methods and seismic reinforcement methods of bridge,points out the existing research deficiencies,and introduces the main contents of this paper.2.This paper reviews the development of bridge seismic design concept,summarizes the changes of bridge seismic design specifications in different periods,analyzes the common seismic damage of simply supported girder bridges and their courses.On this basis,this paper summarizes the seismic reinforcement methods applicable to the existing simply supported girder bridges.3.The three-dimensional finite element model of the sample bridges are established by using Open Sees software.100 seismic waves are selected from the peer seismic database as earthquake input samples,and the nonlinear time history analysis method based on incremental dynamic analysis is used to simulate the seismic damage of the sample bridges.According to existing research results,the damage state equations and criteria of the bending failure,shear failure and bearing deformation failure of the piers are established.4.The vulnerable position of the bridge pier are found of the sample bridges under the longitudinal and transverse seismic action.The seismic vulnerability curve of the vulnerable components of the sample bridges are drawn.According to the current specifications for seismic design of bridges,the artificial ground motion of each site category is synthesized,and the damage degree of vulnerable components of sample bridges under the earthquake action of each site category are evaluated.5.According to the evaluation results of seismic performance of the sample bridges,three seismic reinforcement schemes are determined,which are FRP reinforcement,cable restrainer reinforcement and shear keys reinforcement.The design and finite element simulation of each reinforcement scheme are introduced.This paper systematically studies the influence of each reinforcement scheme on the seismic vulnerability of sample bridges,analyzes the reduction of the damage degree of each vulnerable component under the earthquake of each site category after reinforcement,and comprehensively evaluates the effect of each reinforcement scheme on the seismic performance improvement of simply supported girder bridges.In view of the deficiency of using single reinforcement scheme,the application of combined reinforcement scheme is discussed preliminarily. |
