| In recent years,with the continuous development and improvement of China's transportation system,long span rail-cum-road cable-stayed bridges have been widely used.Due to the complexity of both the stress state and driving conditions of this structural system,it is of great theoretical and practical significance to study the structural characteristics of these bridges and the coupled vibration characteristics under the action of traffic vehicles,so as to make dynamic analysis and assessment on the running safety and stability of train vehicles.In this paper,taking a newly built long span rail-cum-road cable-stayed bridge as the engineering background,the numerical calculation and analysis of the dynamic interaction of the train-automobile-long span cable-stayed bridge are carried out.The main research contents and conclusions are as follows:?1?The research history of dynamic interactions among trains,automobiles and long span bridges at home and abroad and the development trend of coupled vibration of vehicle-bridge system are elaborated,and thus the significance of this paper is clarified.?2?The spatial multi-degree-of-freedom rigid body models of 16 types of automobile vehicles are derived and established.Based on the traffic flow data of Jiangyin Yangtze River Highway Bridge,the basic parameters such as vehicle type,weight,distance and speed are statistically analyzed and a random traffic simulation program was compiled to generate random traffic samples of mixed vehicles.The full-process iterative program for the coupled automobile flow-bridge system is compiled,and the numerical analysis for the bridge under multiple conditions is carried out.?3?A 3D 27-degree-of-freedom vehicle model is established,with the track irregularity as the self-excited excitation,the full-process iterative program for the coupled multi-track train-bridge system is compiled.The dynamic responses of the bridge and vehicles are computed and analyzed under multiple conditions.?4?The analysis model for the train-automobile-bridge dynamic interaction system is established,and thus the dynamic responses of train-bridge system are simulated,from which the interaction between highway and railway traffic loads is discussed to make dynamic assessment on the service reliability of the bridge and the runnability of train vehicles on the bridge.The results show that:1)The contribution of the train vehicles to the dynamic responses of the bridge is significantly greater than that of the automobiles.The vertical and torsional displacement of the bridge deck are mainly controlled by the gravity loading of the moving train.After considering random automobile flows,the lateral displacement,as well as the lateral and vertical accelerations of the bridge deck have increased to varying degrees.2)When multi-line trains and random automobile flows pass through a long-span cable-stayed bridge at the same time,the maximum lateral,vertical,and torsional displacements of the deck are 3.12cm,79.65cm,and 1.82×10-3rad,respectively,and the maximum lateral and vertical accelerations are 0.14 m/s2 and 0.31 m/s2,respectively.3)The automobile flows have a greater impact on the vibration of the train vehicles,and the dynamic responses of the vehicles have increased to varying degrees.Meanwhile,the train vehicles have a greater impact on the vibration of the automobiles.5)When considering multi-line trains and random automobile flows on the bridge at the same time,the maximum lateral and vertical acceleration of the car-body are 0.55 m/s2and 1.19 m/s2,respectively,while the maximum derailment factor is 0.35,the maximum offload factor is 0.44,and the maximum lateral wheel/rail force is 33.13 k N.5)In all calculation cases in this paper,both the dynamic responses of bridges and vehicles can satisfy the requirement of the code limitations. |
PDF Full Text Request