Relationship between track stiffness and dynamic performance of vehicle–track–bridge system

Track stiffness irregularity is superficially invisible on rail surface, while causes dynamical impact and track deformation when trains running through. Aiming at this issue, this work presents an investigation on the influence of track stiffness on dynamic behaviours of the high-speed vehicle–track–bridge dynamic system. Primarily, a determination method of track stiffness irregularity is analytically deduced, in which a novel solution of deformation of free beam is proposed. Then a high-speed vehicle–track–bridge dynamic interaction model is established based on the vehicle–track–bridge dynamic interaction theory. On this basis, the influence of track stiffness on the dynamic behaviours of the coupled system is investigated both in time domain and in frequency domain. Results show that the distribution of track stiffness in longitudinal direction indeed affects the vibrations of the system. More vibration details of system in full frequency bands can be revealed by considering track elasticity. The most sensitive indicator to different track types is the pitch acceleration of bogie. The wave amplitude caused by length of slab is very small, however its influence on vehicle vibrations is great, indicating that tiny track stiffness change caused by length of slab cannot be ignored in dynamic investigations.