Dynamic Impact Of High-speed Railway Bridge Bearing Stiffness On Train-track-bridge System

When the train passes the bridge at a high speed,the vibration generated by the track on the bridge will affect the safety of the bridge structure and the stability of the vehicle operation,and even have a great impact on the surrounding environment.Therefore,it is very necessary to conduct a comprehensive study on the train-track-bridge system to find reasonable measures to reduce the vibration of the bridge structure and ensure the smooth operation of the train.Based on the train-track-bridge interaction theory,this paper firstly adopts the multi-body dynamic method and the finite element method to study and analyze the vertical stiffness of high-speed railway bridge bearing on the dynamics of vehicle-wire-bridge system,and determine the stiffness range of the damping support.Then,using the vertical acceleration of pier bottom foundation as the evaluation index,it quantitatively analyzes the damping performance after the bearing stiffness decreases.Finally,the three-dimensional finite element model of the spherical bearing is established to carry out the optimization study of the vibration reduction bearing,and the mechanical characteristics and stiffness characteristics of the bearing after the optimization are analyzed.The main contents and conclusions are as follows:（1）A coupled train-track-bridge dynamics model was established to analyze the effect of the vertical stiffness of the bearing on the dynamical system.When the vertical stiffness of the bearing is reduced from 3×10¹¹N/m to 3×10⁸N/m,the change of the wheel-rail vertical force and derailment coefficient is not obvious,and the vertical displacement of the rails,track plates and bridges all increase substantially;When the vertical stiffness of the bearing is reduced to3×10⁷N/m,the derailment coefficient increases slightly,the rail vertical displacement exceeds the regulation of high-speed railroad rail vertical displacement,the rail plate vertical displacement exceeds 3mm,and the bridge span vertical displacement and vertical acceleration both increase substantially.Therefore,in order to ensure the safety of traffic,it should be ensured that the vertical stiffness range of the bearing should not be less than 10⁸N/m.（2）Comparing the vibration damping effect of bridge vibration damping bearings and vibration damping fasteners,it is found that the vibration damping effect of vibration damping bearings on the train-track-bridge system is stronger than that of vibration damping fasteners,which verifies the necessity of vibration damping bearings.When the combination of vibration damping bearing+vibration damping fasteners is used,the dynamic response of rails,track plates and bridges is increased,for this reason,it should avoid the adverse effects on the traffic caused by the simple pursuit of vibration damping effect.（3）A three-dimensional finite element model of high-speed railroad spherical bearing is established,and the idea of replacing steel material with polyurethane material is proposed to enhance the vibration damping performance of the spherical bearing,and the material properties that satisfy the stiffness range and vertical displacement regulations of the bearing are calculated by numerical analysis.After studying the mechanical properties of the vibration-optimized spherical bearing,the important parts of the bearing are in the elastic working range under both vertical and horizontal loads,which indicates that the idea of replacing the steel material with polyurethane material to improve the vibration-optimizing performance of the bridge bearing is feasible.Finally,the stiffness characteristics of the vibration-optimized spherical bearing were analyzed,and it was found that the dynamic and static stiffness ratio of the vibration-optimized bearing was 1.24,indicating that the vibration-optimized bearing has good resilience and vibration transmission performance.