Analysis Of Train-Track-Bridge Coupling Vibration Of Single Tower Cable-Stayed Bridge Of High-Speed Railway

Due to the high proportion of bridges in high-speed railway,coupled train-bridge vibration has become a hot topic in the field of railway bridge research.At present,domestic and foreign scholars seldom consider the influence of prestressed steel bundle area variation and stay-cables failure behavior on the dynamic response of single tower cable-stayed bridge in high-speed railway in the study of train-bridge coupled vibration.Therefore,based on a high-speed single tower cable-stayed bridge as the research object,using multi-body dynamics software SIMPACK to establish high-speed train model,ANSYS software is adopted to establish the bridge and track finite element model.The bridge and track model data are imported into the multi-body dynamics software SIMPACK.The vibration analysis model of train-track-bridge coupling system is established.On this basis,the influence factors of train-bridge coupling vibration of long-span single tower cable-stayed bridge are analyzed.The main research contents are as follows:(1)Based on the multi-body dynamics software SIMPACK,the model of twosuspension four-axis train is established by using substructure method.Using ANSYS software to establish track model,combined with flexible track configuration file(*.ftr),the track model is imported into SIMPACK to generate the flexible track body.The coupling between train and track is realized by wheel-rail contact relationship,in which the normal force and the creep force of wheel-rail are calculated by Hertz elastic contact theory and Kalker simplified theory respectively.At the same time,the track irregularity samples converted from German low interference spectrum are used as the external excitation of the flexible track body.(2)The finite element model of long-span single tower cable-stayed bridge is established by ANSYS software.Among them,the prestressed steel bundle and the main beam are connected through the rigid zone,and the correctness of the method is verified by comparing the calculation results of different finite element models;The reasonable value of the initial tension of the stay-cables is determined by the influence matrix method.The flexible input file is formed by the substructure analysis of the bridge finite element model,and the bridge model data is imported into the SIMPACK.Combined with the train and track model,the vibration analysis model of train-trackbridge coupling system of long-span single tower cable-stayed bridge on high-speed railway is established.The self-vibration characteristics of the bridge are analyzed by ANSYS and SIMPACK software.The results show that: 1)The results of the bridge natural vibration characteristics calculated by the two software are basically the same.2)In ANSYS finite element model,the prestressed load is applied in the form of initial strain,and the vertical vibration frequency of the bridge increases and the lateral vibration frequency decreases when considering the prestressed steel beam,but the overall variation is not large.(3)Based on the vibration analysis model of the train-track-bridge coupling system,carry out vibration analysis of long-span single tower cable-stayed bridge in SIMPACK.The influence of prestressed steel bundle,speed,stiffness of main tower,stiffness of main beam and failure of different stay-cables on the dynamic response of bridge is discussed.The results show that :1)The displacement response of the bridge decreases after considering the prestressed steel bundle,and as the area of prestressed steel bundle increases,the displacement response of the bridge shows a monotone decreasing trend.2)The increase of train speed increases the vibration response of train-bridge as a whole.However,the influence of train speed change(150km/h～200km/h)on the vertical dynamic response of the main beam in the middle span and tower top is relatively small.3)Compared to other indicators of the train,changes in the stiffness of the main tower have a great influence on the vertical acceleration response of train body.4)The decrease of beam stiffness will lead to the increase of cable tension variation,and the increase of the longest cable tension variation is the most obvious.5)The failure of the longest cable and the middle cable of the bridge has a relatively large influence on the dynamic response of the bridge.Emphasis should be placed on monitoring and protection.