Study On Reasonable Value Of Transition Track Structure(TTS)for High-Speed Railway Bridge

Abstract:Since the construction of high-speed railway bridge, the load-carrying capability of beam-end track structure is insufficient due to large beam-end deformation for one part of bridge. And the safety and durability of track structure is influenced badly. At present, the influence of beam-end deformation on track structure is mainly reduced by using TTS. The problems in high-speed bridge design to be urgently solved are whether the running stability and comfort of high-speed train can be guaranteed after the set of TTS and the load-carrying of track structure can be decreased furthest by what kinds of TTS. In this dissertation, reasonable value of TTS is investigated based on static and dynamic results. The main contents and contributions of the dissertation are as follows.(1) The mechanism of TTS is discussed. It is testified that the influence of beam-end deformation on track structure can be improved by the TTS.(2) The static calculation model of32m simply-supported beam is established. The effect of reducing load-carrying of track structure by setting TTS is analyzed. The results reveal that when the length of TTS is2.5m, maximum additional uplift forces and minimum stability coefficient of track slab are most decreased(or increased) under staggered platform. Meanwhile, Maximum additional downlift forces and maximum rail stress are most decreased under beam-end rotation angle and staggered platform.Maximum additional uplift forces and minimum stability coefficient of track slab can be reduced by83%-90%and379%-490%under beam-end rotation angle and staggered platform which is changed form0.5%orad and0.5mm to2.0%orad and2.0mm. Similarly, Maximum additional downlift forces and maximum rail stress can be decreased by85%～87%and70%～72%under staggered platform only.(3) The dynamic calculation model of large-span continuous rigid-frame bridge is established. And the corresponding computer program is developed by Fortran90language, by which the influence of TTS on running smoothness and comfort of trains is analyzed. The calculated results show that before and after adding TTS, the dynamic response of car body is different, only when vehicle passing through TTS. At the same time, vertical acceleration of car body is changed obviously, but sperling index is nearly unchanged.(4) Reasonable parameter range of TTS for large-span continuous rigid-frame bridge is proposed based on the static and dynamic calculation results. The conclusion is that length of TTS should be limited from1.3m to2.5m. The bending inertia of TTS need to be not less than6.4×10-4m4. The Fastener static stiffness on TSS should be controlled between20kN/mm and40kN/mm. The reasonable value of fastener spacing on TTS is between600mm and629mm,The optimum value of distance between track-end fastener and bearing for TTS is from300mm to400mm.87figures,27tables,98references in total.