Seismic Safety Analysis Of Urban Rail Transit Bridges And Train

In the first two decades of the 21 st century,China has experienced a period of economic soaring.The process of urbanization in China is also in full swing,and the urban population is increasing day by day,which leads to the increasingly prominent problem of urban traffic congestion.It is inevitable to develop urban rail transit vigorously and form a three-dimensional network,so that traffic congestion could be alleviating on certain scale and traveling choices of the citizen enriched.Research on bridge-vehicle coupled system has become an important subject for the reason that viaduct section takes up a grave proportion of urban rail transit lines.After summarizing the existing research results,a systematic understanding of the principle of dynamic interaction of locomotive-line-bridge is given.The dynamic response pattern of the system under earthquake is obtained,which provides data support for the seismic design of urban rail transit bridges and provides reference for the design of measures to maintain their operational safety.The main work of this paper is as follows:1.The development history of urban rail transit in the past 100 years is systematically introduced.It also collates related research on rail transit and studies the research data on related topics of rail transit bridges at home and abroad and the existing seismic damage data.After showing the main seismic damage situation of locomotive-line-bridge system,we know that research on dynamic response of the system elevated structure and the train safety when earthquake occurs are of great significance.2.The relevant requirements of seismic fortification in the newly promulgated and implemented Code for Seismic Design of Urban Rail Transit Structures are sorted out and compared with the relevant parameters of the original one.The analysis methods and indicators of safety and stability of railway trains on bridges at home and abroad are collected,and the dynamic response indexes of locomotive-line-bridge system suitable for the earthquake action in this paper are chosen by referring to the existing codes in China.Limits used for evaluating the dynamic response safety of bridge structures,and the equivalent horizontal forces acting on the bearing and pier top joints are calculated to evaluate the safety reserve of structures under various design conditions.3.The theoretical model of structural dynamics of the main components of the locomotive-line-bridge system is presented.The model is established by using simulation software ABAQUS.According to the site conditions,several ground motion records are chosen and processed as seismic excitation for simulation analysis under various working conditions;the track irregularity excitation of this model is taken from the six-level spectrum of the U.S.track.The track irregularity simulation samples are obtained using MATLAB,then it is realized to the track model by attaching coordinates.4.Considering the difference of design parameters in different codes and the influence of earthquake intensity,driving speed and track irregularity grade,a variety of pertinent analysis conditions are designed.The seismic safety analysis of the bridge-train system model under various working conditions is carried out,the dynamic response of the bridge under the combined action of earthquake and train is given,and the possible failure state of the bridge structure is analyzed.The response of the train and Bridge under different influence factors is given,and the seismic safety of the bridge-train system is analyzed.Relevant conclusions with reference value have been reached.