Analysis Of Vertical Vibration Response Of Vehicle—ballastless Track—bridge System

Due to of its low level of maintenance, good stability and durability as well as smoothness in running train, the ballastless track has been widely used in high-speed and inter-city rail system. Contrary to the traditional ballasted track, the ballastless track may induce high noises and vibration response for its higher stiffness. Thus it is important to conduct some research on the vibration analysis of vehicle-ballastless track-bridge system. In this thesis, a dynamic model for the vibration analysis of the high speed vehicle-ballastless track-bridge coupled system, which is about slab track, is established based on the principle of unchanged value of the total dynamic potential energy of elastic system and the "right position" rule. A corresponding program was developed on the platform of Fortran PowerStation 4.0 by FORTRAN. With the excitation of vertical irregularities of rail, the simulation computation of vibration response was carried out. The main works in this thesis are listed as follow:First, the dynamic FEM equation for the vehicle-track-bridge (V-T-B) system was deduced and the total mas, stiffness damping stiffness were listed out. With the developed program, the dynamic reponses of a standard 24m simply supported beam transversed by twelve vehicles at various speeds were calculated. The numerical results show good agreement with those made by the previous researchers. Then with the Ronggui Shuidao Bridge of Guangzhu intercity railway project as the engineering background, the dynamic reponses of a long-span rigid-frame PC bridge under 12 vehicles transverse at different speeds were computed. And the effects of the rail irregularities were considered and the results with/without the ballastless track structures were obtained. Finally with the variations of eight parameters of the ballastless track structure, detailed analyses of the V-T-B system were carried out and the numerical results were compared among those responses. And a favour set of parameters was concluded. With these new proposed values of the ballastless track structure, the dynamic response of the track, vehicle and bridge structure may be reduced dramatically. The research of this paper may provide some guides for the designing and construction of long-span bridges with the ballastless track in the future.