Study On Seismic Vulnerability Of High-pier And Long-span Continuous Rigid Frame Bridges During The Whole Life Cycle

Looking back on the building process,we can easily find that,compared with other structural types,concrete is a new type of structure,which has been developed for more than one hundred years.Although the development process is short,it plays a vital role in the engineering structure.So far,in the field of civil engineering,no matter in the field of construction or bridge structure,reinforced concrete is one of the most widely used structural forms.Reinforced concrete Bridges account for a large proportion of the Bridges under construction in the world at present.In the process of studying the mechanical properties of bridge structures,we found that:under the influence of environment,load and internal uncertainty of the structure,the structural properties of concrete structures will constantly change during the use process,and the damage change process becomes extremely complex due to the uncertainty of the factors affecting material degradation.In order to study the seismic vulnerability of the bridge in the whole life cycle,the Jinshui Gou Bridge is taken as the background.Midas/Civil software is used to build the finite element model,and Origin,XTRACT and MATLAB software are used for data analysis,mainly to analyze the vulnerability of the bridge components and the system,the correlation between concrete carbonation and steel corrosion.The main research contents are as follows:1.Based on the general situation of the bridge engineering,the three-dimensional finite element model of the whole bridge was established based on MIDAS/Civil finite element software;The calculation method of natural vibration characteristics is briefly introduced,and the natural vibration characteristics are analyzed in the finite element software MIDAS/Civil.2.According to the site conditions and ground motion characteristics of the bridge,15 seismic waves meeting the requirements were selected from the PEER ground motion database,and the selected seismic waves were adjusted and input into the nonlinear finite element model.and the selected seismic waves are adjusted and input into the nonlinear finite element model.3.Analyze the advantages and disadvantages of different structural failure criteria,select the appropriate structural failure criteria,select the damage index consistent with the failure characteristics of the bridge in the calculation example,and conduct the moment curvature analysis of the structure.The bridge pier is quantified with the help of XTRACT software to quantify the damage index.4.Incremental dynamic analysis was performed on the sample bridge and log-linear regression analysis was performed on the obtained data to plot the component vulnerability curve.Based on the exceedance probability of the vulnerability of piers and supporting members,the first-order boundary estimation method is used to draw the vulnerability curve of the system.5.According to the natural environment of the bridge,the concrete carbonation is studied,and the concrete carbonation depth of the sample bridge with different service life is obtained.The time varying curve of the carbonation depth with the service life is obtained.Be drawn.The initial corrosion time of stirrups and longitudinal reinforcement is obtained by studying the corrosion of reinforcement materials.6.Modify the parameters of reinforcement materials and coagulant materials in the finite element model,and carry out the vulnerability analysis for the example bridge in each service life,and get the vulnerability curves of the components of the example bridge and the system in each service life,as well as the vulnerability surfaces of the components and the system in the whole life cycle.