Vehicle-Bridge Coupled Vibration Analysis Of Large Span Bridge With High Piers

The vehicle-bridge coupled vibration of large span bridge with high piers is mainly re-flected in two aspects. First, it is the study of the dynamic response of the large span bridge with high piers under the high-speed and heavy-haul train. Second, it is the study of s running ecurity and stability of the train on the bridge.In this paper, Zongmu Ditch Bridge is regarded as engineering background. The structure type of the bridge main span is variable cross-section of prestressed concrete continuous rigid frame. The span is (78+2*136+78) meters. The4th pier and the6th pier are double thin-wall piers and each is48meters high. The5th pier is the new column plate hollow high pier and the height is105meters. The analysis and research of vehicle-bridge coupled vibration of the large span bridge with high piers is carried out. In order to analysis and research of ve-hicle-bridge coupled vibration of the large span bridge with high piers, the relevant data and documents are collected and arranged. The vehicle dynamic analysis model of31degrees of freedom is established. Using the D’Alembert principle, the dynamic equations of the ve-hicle are educed. The three-dimensional space finite element analysis model of Zongmu Ditch Bridge is established by the ANSYS software. Using the modal synthesis method, the dynam-ic characteristics (frequencies and mode shapes) of the bridge is analyzed and calculated. Combined with the relevant norms, the calculation results of the natural frequency are eva-luated. On the basis of both domestic and foreign norms and experimental research results of the vehicle system and the bridge structure, the dynamic response analysis and evaluation system of the vehicle-bridge coupling system was established. The three-dimensional space finite element analysis model of the bridge established by the ANSYS software is imported the UM (Universal Mechanism) software by the ANSYS-UM.EXE program, is connected to the vehicle model through the UM software. The track irregularity and the serpentine wave of wheelset as excitation source of the vehicle-bridge coupled vibration system. The simula-tion analysis model of the vehicle-bridge coupling vibration of Zongmu Ditch Bridge is established. The study of vehicle-bridge coupling vibration of the large span bridge with high piers is achieved by joint simulation analysis. The driving stability of different types of vehicles (locomotive, passenger car and goods vehicle) is analyzed, and the nonlinear critical speed of vehicles is calculated. When locomotive, passenger train or overloads goods ve-hicle pass through the bridge at design speed, the dynamic response of the bridge structure and the vehicle system are analyzed. On this basis, influence of bridge structure stiffness, running speed, track irregularity, or marshalling etc on the vehicle-bridge coupled system of the large span bridge with high piers are discussed.The results obtained in this study can be concluded as follows. The top10mode shape of Zongmu Ditch Bridge is mainly lateral vibration. This shows that the lateral stiffness of Zongmu Ditch Bridge is relatively small. When passenger train or overloads goods ve-hicle pass through the bridge at design speed, each dynamic response indicator of the bridge structure and the vehicle system does not exceed the specification limits. When the bridge lat-eral stiffness (lateral stiffness of main beams and piers) decrease, impact on lateral vibra-tion of the vehicle-bridge coupled system is obvious, and the impact on vertical vibration of the system is little. When the vertical stiffness of main beams change, impact on vertical vi-bration of the vehicle-bridge coupled system is obvious, and the impact on lateral vibration of the system is little. With the increase of the traveling speed, each of dynamic responses of the vehicle system and the bridge structure is increased in general. Due to increase of the track irregularity, the vibration of vehicle-bridge coupled system is significantly intensified. This shows that the track irregularity is one of main excitation source. The lateral stability of the empty goods vehicle is weaker than the lateral stabilit of the overloads goods vehicle. The empty goods vehicle prone to derailment accident.