Study On Seismic Performance Of Urban Rail Transit Bridge Structures Based On IDA Analysis

With the rapid development of the national economy of China and the rapid growth of urban population,urban transportation are becoming increasingly tense. Urban rail transit has a big,fast,safe,reliable,less interference with other traffic characteristics and it will become the preferred way to solve traffic congestion in medium-sized cities in China.Because the elevated line has the advantages of low cost and small power consumption,it has a increasing proportion of urban rail transit,especially in the connecting line between the urban centers and the rural areas.However,it has less study of the seismic capability of the elevated bridge and the function of the elevated structure after the earthquake continuing to play lack of research.So detailed analysis of the seismic capability of the urban rail transit bridge as the lifeline is very necessary.This article describes the theory of IDA in detail,at the same time by choosing a set of representative seismic records that they are compatible with the norms,selecting the spectrum of T₁ acceleration department Sa(T₁) as the intensity measurement parameters(IM),using the Incremental Dynamic Analysis(IDA),it analysises the seismic capability of typical urban rail transit bridge in Beijing at different levels of seismic intensity measurement parameters.The major studies and creative intents are as follows:1.Earthquake recordings selection and the efficiency of alternative ground motion intensity measures selection;2.Framing a typical fiber-based finite element mode of urban rail transit continuous beam bridge;3.Analysising the vibration characteristics of bridge and testing the model;4.Using a number of records for the IDA analysis of the fiber-based model,fitting the drift ratio with the lognormal distribution and IDA curves with the mean and the fractile,The results show that the IDA curve can well reflect the seismic capability of typical urban rail transit bridge under strong seismic performance;5.Using the Park-Ang damage assessment of two-parameter model based on Jianghui,Zhu Xi and other amendments and analysising the indicators of seismic damage and destruction of state of typical urban rail transit bridge in Beijing at different levels of seismic intensity,the work provids a good reference for seismic performance evaluation and design of urban rail transit bridges.