Parameterized Seismic Vulnerability Analysis Of Regional Regular Simply-Supported Girder Bridge

In recent years,the evaluation of seismic performance of small and medium-sized simplysupported girder bridge is no longer limited to the single structure,but to the group structure of a certain line or region.How to quickly complete the pre-earthquake design and postearthquake evaluation of such bridges has become an urgent problem to be solved.From the perspective of seismic vulnerability,this thesis takes the highway simply-supported girder bridge on the trunk line of Yunnan Province as the research object.According to the structural characteristics of the regional simply-supported girder bridge,this thesis focuses on the establishment of the sample library of the regional simply-supported girder bridge,the seismic response analysis of the regional simply-supported girder bridge,the establishment of the probabilistic seismic demand model based on deep learning and the study of the parametric seismic vulnerability analysis method of the regional simply-supported girder bridge.It realizes the rapid and effective evaluation of the reliability of the regular simply-supported girder bridge,and provides a reliable technical reference for the design,construction and reinforcement and maintenance of the regional simply-supported girder bridge.The main research contents are as follows :(1)Aiming at the problem of diversity of structural parameters and randomness of parameter values in the process of seismic vulnerability analysis of regional simply supported bridges,the correlation between variables is quantitatively calculated by mathematical method to ensure that only relatively independent variables are input into the whole bridge.A reasonable sample library of regional simply supported bridge parameters is established by comparing different uniform test design schemes.(2)The modeling method of finite element model of simply-supported girder bridge is discussed,and the correctness and rationality of the simplified finite element model are verified.Based on the nonlinear time-history method of incremental dynamic analysis,the seismic damage of bridge samples is simulated,and the vulnerable position of pier under longitudinal and transverse seismic action is determined.According to the structural failure criterion,the damage index of pier is quantified.(3)Aiming at the complex nonlinear mapping relationship between seismic design parameters and structural response of regional simply-supported girder bridges,a probabilistic seismic demand substitution model based on MLP is established.The network structure,activation function,loss function and optimization algorithm are compared and selected.The effect of MLP network training and prediction is verified,and the prediction of seismic response of regional simply-supported girder bridges is realized.(4)The basic steps of realizing the parametric seismic vulnerability analysis of regional simply-supported girder bridge based on Lasso-Logistic model are introduced in detail,and the parametric seismic vulnerability function of regional simply-supported girder bridge is established.Compared with the traditional seismic vulnerability method,the feasibility and practicability of this research method are verified.