Earthquake Under The Action Of High-speed Rail Continuous Steel Truss Bridge Coupling Vibration Study

In order to meet the requirements of safety and smooth lines, and reduce the interference of surrounding factors, it needs to construct a lot of viaduct, which making the percentage of bridge total length is high in high-speed railway. When the line is in earthquake-prone zone, the earthquake is very likely to occur while the train passing the bridge. Therefore, it is very necessary to study the dynamic response of the bridge and the train running performance and safety under earthquake. Drawing on the earlier research in the field of couple vibration, and using continuous steel truss bridge of Zhengzhou Yellow River bridge with a 5 x120m span for engineering background, a dynamic simulation and research about the dynamic response of the bridge and trains running safety are made while the seismic and train loading at the same time. The contents of this paper are as the following:1. Summary of the research of couple vibration at home and abroad on the history and at the present time, and discuss the necessity of the study on vehicle-bridge coupled vibration systems under earthquake.2. A relatively perfect model of the dynamics of vehicle and bridge is established. Aimed at the three truss characteristics of Zhengzhou Yellow River Bridge, while the edge truss tilting outward and forming inverted trapezoidal cross-section, by improving the truss finite element model, a inverted trapezoidal three truss finite element model is established to simulate the bridge . Based on the principle of total potential energy with stationary value in elastic system dynamics and the "set in right position" rule for formulating system matrixes, the overall vibration equation of corresponding vehicle- continuous steel truss bridge time dependent system is established.3. Based on the above bridge model, the natural vibration frequencies are calculated. And according to the vibration modes, it makes a study on the dynamic characteristics of the bridge.4. By improving the analysis model of the time-dependent train continuous steel truss bridge system and introducing the seismic waves, the coupled vibration response of the continuous steel truss bridge under earthquake is calculated. So that the largest transverse, vertical displacements, the largest transverse, vertical accelerations and the coefficients of impact of different bridge locations under different strength of earthquake are obtained. At the same time, the derailment coefficient, load decrement rate of wheel weight, lateral oscillation force, transverse and vertical acceleration, Sperling comfort criteria are obtained. Finally come to the conclusion: the traffic safety of the bridge can be assured whether in the absence of earthquake or under small earthquake, and can't be assured under the moderate earthquake and intense earthquake function.5. The influence of seismic wave to the dynamic responses of the long-span continuous steel truss bridge is studied. The results show that:①the transverse seismic wave has important impact to the transverse dynamic response of vehicles and bridges. Because of the small torsional rigidity the truss bridge, the transverse seismic wave influences the vertical vibration of the vehicles and bridges to a certain extent;②the vertical seismic wave has a major impact on the vertical vibration of the vehicle-bridge system while has little effect on the transverse vibration. However, the influence of the vertical seismic wave to the derailment coefficient, the load decrement rate of wheel weight and the vertical acceleration is so significant that it needs to consider the impact of vertical seismic wave when judged safety of trains;③the dynamic response of the bridge depends primarily on the size of the earthquake, while the speed of the vehicles contribute little to the bridge response. And under small earthquake, the speed has more contribution to the vehicles dynamic response, and the greater speed the easier it is to derailment.