Analysis Of Train-track-bridge Coupling Vibration Of High-speed Railway Tied-arch Bridge Under Earthquake

As one of the important infrastructures of railway,bridge is also a key project in railway construction,which shows unique advantages in crossing complex terrain and realizing line closure.Therefore,bridge structure is taking up an increasing proportion in the construction of high-speed railway in China.It makes the probability of highspeed trains traveling on bridges increasing when earthquakes occur,while the complexity of the interaction between trains and bridges is higher,and the safety and stability of train operation will be greatly affected.Therefore,this paper takes a highspeed railway concrete-filled steel tube basket tied arch bridge as the research object to carry out the train-track-bridge coupled vibration analysis of high-speed railway tied arch bridge under the action of earthquake.The main research contents are as follows:(1)Train-track-bridge coupled vibration analysis method under earthquake based on SIMPACKThe German ICE-3 train model was established by SIMPACK,a vehicle-bridge coupling vibration analysis software.The single train consists of 1 car body,2 bogies and 4 wheelsets,with 7 rigid bodies and 42 degrees of freedom.The finite element model of track is established by ANSYS software,and it is imported into SIMPACK software to generate flexible track body according to the integration method of multibody system.The quasi-elastic contact model is used to simulate the wheel-rail contact relationship,and the rail-beam connection mode is simulated by setting the equal spacing fastener force.The low interference spectrum of Germany is transformed into the input function of track irregularity in the spatial domain and imported into the track to realize the input of track irregularity excitation.The corrected seismic wave acceleration,velocity and displacement time history are imported into the bridge and track as input functions to realize the input of seismic excitation.Taking 30 meters simply supported beam as an example,the seismic time history response analysis is carried out by using SIMPACK and bridge finite element analysis software MIDAS/civil to verify the feasibility of bridge seismic response analysis in SIMPACK software,(2)Establishment of vibration analysis model of train-track-bridge coupling systemCombined with practical engineering,the finite element model of high-speed railway tied arch bridge is established by ANSYS software,and the flexible body is generated by data conversion to SIMPACK software.The natural vibration characteristics of the bridge structure are compared and analyzed to verify the accuracy of the import method of the bridge finite element model.Combined with the train and track model and the train-track-bridge coupling connection mode,the vibration analysis model of train-track-bridge coupling system is established.(3)Evaluation and analysis of dynamic response of train-track-bridge coupling system with or without earthquakeAccording to the dynamic response evaluation criteria of train and bridge,based on the vibration analysis model of train-track-bridge coupling system,three typical seismic waves are selected to calculate the dynamic response of train and bridge under the uniform excitation mode of seismic waves in the combination direction of transverse and vertical bridge directions,and the dynamic response of train and bridge without earthquake is compared and analyzed.The results show that the safety indexes of train and bridge have high redundancy when there is no earthquake,and the influence of earthquake on the dynamic response of train and bridge is obvious.The influence of different seismic waves on the dynamic response of train and bridge is quite different.When the peak ground motion is 0.1 g,the train can maintain safe operation.(4)Analysis of influencing factors on dynamic response of train-track-bridge coupling system under earthquakeBased on the above train-track-bridge coupled system vibration analysis model,the modified El Centro wave is selected.In the combination direction of transverse and vertical directions,the influence factors of train-track-bridge coupled vibration of highspeed railway tied arch bridge under seismic action are analyzed by using uniform excitation mode.The influence laws of vehicle speed,seismic intensity,rise-span ratio of bridge and track fastener failure on train-track-bridge coupled vibration are discussed.The results show that:1)The change of vehicle speed has no obvious effect on the dynamic response of the bridge under earthquake.The safety and stability of train operation increase with the increase of vehicle speed,but it does not exceed the corresponding limit.2)The seismic intensity has significant influence on the dynamic response of trains and bridges,and the safety of trains and bridges cannot be guaranteed when the peak ground motion exceeds 0.2 g.3)The change of rise-span ratio of bridge under seismic action has obvious influence on the dynamic response of arch rib,and the mid-span displacement of main beam gradually increases with the decrease of risespan ratio.4)Under the action of earthquake,the failure of rail fasteners has a significant impact on the dynamic response of the main beam.When the number of rail fasteners failure reaches 5,the train derailment occurs at the middle position of the main beam.