The Study On Coupling Dynamic Problem Of Maglev Train-bridge System

Based on the theory of vehicle-bridge coupling dynamic interaction and taking the 25m typical simply supported prestressed concrete box girder on the Changsha maglev Express as case study, the model of vehicle-bridge coupling dynamic interaction is established in this paper and the inter-system iteration method is used for calculation. Taking the track irregularity as random excitation and taking the electromagnetic force as the connecting link, the response law of the maglev vehicle-bridge coupling dynamic interaction is emphatically analysed. Then, the influence factors about the impact effect of low-medium speed maglev viaduct are discussed and the design of the track beam is studied. In the end, the relationship between the dynamic coefficient and the speed is analyzed. The main contents and conclusions are as follows:(1)When studying the maglev vehicle-bridge coupling vibration, the author only takes the vertical vibration into consideration rather than the lateral vibration in this papor. The inter-system iteration method, which is of high computational efficiency and high controllability about convergence process, is used for calculation in the process of solving the maglev vehicle bridge coupling vibration. The method is proved to be feasible by calculation.(2)The dynamic mechanism about the electromagnetic levitation of the low-medium speed maglev train is analyzed. The calculation formula of the dynamic electromagnetic suspension force is derived, and the dynamic characteristics of the electromagnetic levitation are summarized.(3)On the basis of summarizing and analyzing the existing research results, the maglev vehicle-bridge coupling model is established and the parameter selection method of track irregularity model is introduced in this paper. The dynamic response of maglev vehicle-bridge with the track irregularity excitation is solved by inter-system iteration method.(4)When the maglev train’s speed ranges from 10 km/h to 80 km/h, the dynamic coefficient of guideway girder increases with the speed increasing and is smaller than 1.2, which proves that the dynamic response of the guideway girder is very small and the good dynamic performance of the guideway girder of Changsha maglev Express is reflected with the low speed. In addition to speed, vehicle weight is an influence factor. Considering maglev vehicles with the different weight, the dynamic responses of the maglev vehicle-bridge coupling system increase with the increasing of vehicle weight.(5)In the viaduct impact effect studying, the effect of vehicle weight, speed, bridge damping ratio and guideway girder section size of a simply supported beam to dynamic coefficient is discussed. Dynamic coefficient increases with the increase of the weight and speed but decreases with the bridge damping ratio increasing.The partial adjustment of the track beam section size has little effect on dynamic coefficient, and the main controlling factor of concrete section dimension is stiffness.(6)When the bridge damping ratio, load length and span are determined and the maglev train’s speed ranges from 10km/h to 80km/h, relationship of dynamic coefficient and vehicle speed is obtained with a lot of simulation calculation. At last, the linear fitting formula of the dynamic coefficient and the speed is obtained.