Coupling Vibration Analysis Of High-Speed Railway Beam-Arch Composite Bridge

With the rapid development of China's high-speed railway,high-speed railway has become one of the most important means of transportation in China today.Bridges account for a large proportion of high-speed railway lines.Therefore,the vehiclebridge coupling vibration problem has always been a hot topic of concern for researchers.The continuous beam-arch composite bridge has the characteristics of strong spanning ability,beautiful appearance,and large structural rigidity.So,it is widely used in high-speed railways.At present,scholars at home and abroad have relatively few researches on the vehicle-bridge coupling vibration of continuous beamarch composite bridges,and most of them have rarely considered the impact of cable fracture or failure behavior on the vehicle-bridge dynamic response.Therefore,this thesis takes a high-speed railway beam-arch composite bridge as the research background,based on the train-bridge-track coupling system vibration analysis theory,using Ansys software to establish a refined finite element model of the long-span beamarch composite bridge-track system.Then the model data is converted,and the vehiclebridge coupling vibration analysis program of the high-speed railway is used to analyze the influencing factors of the vehicle-bridge coupling vibration of the high-speed railway beam-arch composite bridge.The main research contents are as follows:(1)Based on the vibration analysis theory of the train-bridge-track coupling system,the coupling system is divided into two subsystems: train and bridge-track.Then establish their dynamic analysis models and derive their equations of motion.Calculate the wheel-rail interaction force based on the wheel-rail contact geometric relationship to obtain the external load of the train and the bridge-track subsystem.The vehicle-bridge dynamic response is obtained by using the new fast explicit numerical integration method and the Newmark-? method to solve the equations of motion of the train and the bridge-track subsystem.Finally,the compilation process of the vehiclebridge coupling vibration program is summarized.(2)The general finite element software Ansys is used to establish the finite element model of the long-span beam-arch composite bridge-track system.Among them,concrete-filled steel tube arch ribs were simulated using an improved equivalent section method.The reasonable value of the initial tension of the cable is determined by the two methods of "impact matrix method" and "iterative method".The track structure is refined and discretized according to CRTS ? slab ballastless track.The influence of the track structure on the natural vibration characteristics of the bridge is analyzed.Finally,the Ansys finite element model data of the bridge-track system was converted according to the data format required for the high-speed railway vehiclebridge coupling vibration analysis program.(3)A vehicle-bridge coupling vibration analysis program for a high-speed railway is used to carry out vehicle-bridge vibration analysis of a train-long-span beam-arch combination bridge-track coupling system.The effects of vehicle speed,arch rib section,main beam height,cable breakage,and failure of different cables on the dynamic response of the bridge were discussed,and the safety of the bridge was evaluated according to the high-speed railway bridge dynamic response evaluation criteria.According to the research results of this thesis,when the train speed is 150 km / h,the bridge acceleration response is the largest;when the train speed is 200 km / h,the bridge acceleration response is the smallest.The reduction of the cross-sectional area of the arch rib has a greater impact on the displacement response of the arch rib of the bridge,but the impact on the mid-span acceleration response of the main beam and the internal force of the cable is minimal.The breakage of the cable has a great effect on the bridge,and the T7 cable has a particularly obvious effect on the structure.Among the factors studied in this thesis,the main beam height and cable breakage are the main factors affecting the dynamic response of the bridge.Bridge operation should focus on the cable near the mid-span.