Study On The Seismic Performance Of Large-span RC Continuous Girder Bridge Of High Speed Railway And Reasonable Reinforcement Level Of Piers

ABSTRACT:At present, the high speed railway is in the period of large-scale development. High-speed railway bridge is the main basic engineering structure of high-speed railway. Meanwhile, the continuous girder bridge is one of the main type of high speed railway bridges. The seismic performance and reinforcement level of large-span continuous girder bridge of high speed railway are not only an important research direction at present, but also an important part of the performance-based seismic design. In this paper, the main research contents are as follows:(1) The related regulations for axial compression ratio, longitudinal reinforcement ratio and transverse stirrup ratio in the typical seismic code of countries were researched. Lots of information of typical continuous girder bridges of high-speed railway were collected. The factors that influence the ductility of piers were summarized and the parameters (axial compression ratio, longitudinal reinforcement ratio and transverse stirrup ratio) of collected bridges were extracted and analyzed. In addition, the parameters range of the current existing continuous girder bridge of high-speed railway were confined in order to lay the foundation for the following study.(2) The two kinds of bridge piers with rectangle and round-end cross-section were simulated, and the parameters analysis of them were performed in the longitudinal and transverse direction respectively. The main conclusions are as follows:Equivalent yield bending moment increases with the increase of the three parameters, displacement ductility coefficient decreases with the increase of axial compression ratio and longitudinal reinforcement ratio and increases with the increase of transverse stirrup ratio in the two directions.(3) The whole bridge model of two high-speed continuous girder bridge were set up. In the longitudinal direction of the bridge, setting longitudinal reinforcement ratio (-75%,-50%,-25%,0,+25%,+50%,+100%,+150%) comparisons under the condition of orginal longitudinal reinforcement ratio and transverse stirrup ratio (0,+100%) comparisons under the condition of orginal transverse stirrup ratio. In the transverse direction of the bridge, setting longitudinal reinforcement ratio (-75%,-50%,-25%,0,+25%) comparisons under the condition of orginal longitudinal reinforcement ratio and transverse stirrup ratio (0,+100%) comparisons under the condition of orginal transverse stirrup ratio. The distribution characteristics for the bending moment and shear force in the bottom of the piers, displacement of bridge’s girder, deformation ductility in the top of the piers, hysteretic energy in the bottom of the piers and damage index of piers under different longitudinal reinforcement level in three viberation levels were discussed quantitatively through the nonlinear dynamic time history analysis.(4) The reasonable reinforcement scope of rectangular and round-end piers of continuous girder bridge of high-speed railway were put forward according to the three primary standards which are the strength requirements of each pier under minor earthquake, the deformation control requirement and damage control requirement of each pier under strong earthquake.