Dynamic Response Of Train-bridge Space-coupling System For Rubber-tired Rail Transit

Both rubber-tired light-rail train and monorail train use rubber-tired bogies and run on city elevated lines which are mainly bridge-lines. Both rubber-tired Light Rail Transit (LRT) and straddle monorail transit are particularly suitable for the external traffic in big cities and the mountainous cities because of their low noise, little vibration, low cost and good climbing ability. The bogies’structure is unique. Some features of rubber-tired LRT and straddle monorail transit, such as the running mechanism, guiding mechanism and wheel-rail contact relationship, differ from those of ther rail transits with steel-wheel bogies, so the train-bridge coupling vibration has also uniqueness. At home and abroad, few dynamic analyses of the train-bridge space-coupling system for rubber-tired rail transit have been studied, and the mature vibration theories and key technologies have not yet been acquired. Based on summarizing and absorbing the achievements in the pioneer works, some research work on rubber-tired LRT which hasn’t been built in China and straddle monorail transit which was first introduced into China has been done in this paper as following:1. According to the structure and running features of rubber-tired rail trains, a 31-degrees-of-freedom dynamic model has been assumed for a car in a rubber-tired light-rail train, while a 15-degrees-of-freedom dynamic model has been assumed for a car in a monorail train. According to the deformation of the suspension springs, the spring deformation energy and damping-force potential energy of the vehicles were deduced. Then, the inertia potential energy and gravitational potential energy of the vehicles were also deduced. Finally, the total potential energy of the vehicle spatial vibration was acquired.2. According to the standard beam structure of Shanghai Pearl Line and Chongqing monorail line, single-box-double-cell box girder element and single cell box girder element of 16-degrees-of-freedom have been established by the finite element method. Two bridge space vibration models for the rubber-tired rail transits have respectively been assembled by the corresponding box girder elements. The strain energy of the bridges was composed of the deduced strain energy of plate beam elements, diaphragms and side walls. According to kinematics, the inertia potential energy of the bridges was also deduced. The damping matrix of the bridges was acquired by Rayleigh proportional damping model. Finally, the total potential energy of the bridge spatial vibration was acquired.3. According to the basic assumptions of pneumatic tire model, the cornering model and radial model of the rubber tires of rubber-tired LRT and straddle monorail transit have been put forward by describing the running mechanism and guiding mechanism of the rubber-tired bogies. The rubber-tired radial model composed of linear spring and viscous damping can simulate the wheel-rail radial viscoelastic contact. The side slip angle, cornering force, aligning torque and cornering potential energy of the pneumatic tires were deduced. And the spring deformation energy and damping-force potential energy of the wheel-rail radial contact were also deduced.4. Referring to the sixth grade track irregularity power-spectral-density of U. S. railways, the samples of level track irregularity and direction track irregularity were simulated by the trigonometric series approach. The train and bridge of rubber-tired rail transit were considered a large system, and the track irregularity was used as the excitation source of the system. The dynamic equations of the train-bridge space-coupling system for rubber-tired LRT and straddle monorail transit were respectively established by the variation principle of potential energy and the "sitting in the right seat" principle. The Newmark-βstep integration method was selected to solve the dynamic equations. The dynamic analysis programs of the train-bridge space-coupling system for rubber-tired LRT and straddle monorail transit were respectively finished by FORTRAN 95 language.5. The dynamic responses of Z206-25 standard rail beam in the typical section of Chongqing straddle monorail transit were calculated. The calculation results of train-bridge system were compared with the field test results, and the correctness of the train-bridge analysis theory and computing program of straddle monorail transit was well validated. At the same time, the correctness of the train-bridge analysis theory and computing program of rubber-tired LRT was well validated.6. The dynamic responses of the train-bridge space-coupling system for rubber- -tired LRT were studied in China for the first time. And some regularity of vehicle acceleration, bridge acceleration, bridge deflection and wheel-rail contact response was acquired. The ride comfort of vehicle and the reduction rate of wheel load were evaluated, and wheel-rail contact parameters were optimized. These studies provided a theoretical reference for the latter domestic construction of rubber-tired LRT.