Study On Seismic Response Of Bearing Of High-speed Railway Bridges Considering The Influence Of Track Constraints

High-speed railway bridges are generally long, and most of them use ballastless track system. The ballastless track interacts with bridges by shear alveolar and sliding layer under the seismic action, which enhances the coupling effect of each spans. Therefore, it is necessary to study influence of track constraints on seismic force for the high-speed railway bridge bearings. Based on multi-span simply supported girder bridges and continuous bridge as the engineering background, combined with the structural characteristics of CRTS II slab ballastless track system, the traditional model and the finite element model of considering track constraints are established to study influence of track constraints on horizontal seismic force of fixed bearings. The main research work is as followed:(1)Through consulting a large number of domestic and foreign literatures, the earthquake damage of bearings, the cause of bearings' failure and the current research status of bearing seismic are introduced.(2)The traditional model and considering constraints models for simply supported bridge and continuous bridge are established, and the single pier model for simply supported bridge is also established. These models are used to conduct modal analysis and response spectrum analysis under the low-level earthquake.(3)Under the design earthquake, the influence of rail system parameters on the horizontal seismic force on fixed bearings is studied. The results showed that: the stiffness of track system and the friction coefficient between support layer and beam have significant effect on horizontal seismic force of fixed bearings, while the influence of stiffness of termination cutting off is insignificant.(4)Set up a series of finite element models considering track constraints to study the influence of parameters such as pier stiffness and site condition on seismic force of fixed bearings.(5)Under the high-level earthquake, the influence of track constraints on seismic force of bearings with considering elastic-plastic is studied. The results showed that: the response peak of seismic force of fixed bearings is decreased when the pier height is equal. But the response peak of seismic force of fixed bearings for short pier is amplified by 17.5% when the pier height is different.