Seismic Fragility Of Continuous Beam Bridge Using Fuzzy-stochastic Method

China is an earthquake-prone country.The frequency of seismic activity is high,its'intensity is large and its' distribution is wide.In general,China is a country with serious earthquake disaster.Earthquake will cause huge loss of life and property to the country for it happens suddenly and has a devastating effect,A smooth transport system after the earthquake will be very helpful to the disaster relief work,As an important hub project in the transportation system,bridges will not only affect the transportation of earthquake relief materials directly,but it will also affect the progress of post-disaster reconstruction.Therefore,the study of seismic performance of bridges is very significant.This paper analyzes the performance-based vulnerability of reinforced concrete continuous beam bridges.The main content is as follows:(1)We will create a three-dimensional finite element model of full-bridge and introduce material constitutive relations and element models in detail.Modal analysis of the finite element model will be conducted and according to the results of modal analysis,we will know whether it is necessary to create a three-dimensional model.(2)Considering the uncertainty of ground motions,100 seismic waves will be selected as seismic input.According to the characteristics of the components,the pier column will select the max displacement ductility ratio as seismic demand and the bearing will select the max displacement as seismic demand.By performing linear regression on the data of dynamic time history analysis,we will obtain the probability demand model of bridge components.Comparing the demand model under different intensity indexes,we can find that the demand model with spectral acceleration(Sa)has less discreteness and better fitting effect.(3)The structural vulnerability analysis is based on the damage index and we will use fuzzy damage index.The damage process of structure will be described by fuzzy mathematics.The membership function will be used to simplify the uncertainty of damage index.Based on the classical reliability theory,the failure probability of the structure using fuzzy failure criterion will be derived.(4)The failure probability function of the structure will be established by selecting some membership functions.After the analysis of vulnerability of structure,we will obtain the vulnerability curves of different components under the ground motion of different direction.(5)Based on the vulnerability of components,the vulnerability curve of the bridge will be established.