The Impacts Of Creep Deformation Of Long-span Prestressed Concrete Continuous Beam Bridges To Coupled Vibration Analysis Of Train-Bridge System On High-speed Railway

At present, medium and short span bridges are primarily adopted on high-speed railway in Japan, France, Germany and other countries. The main structure forms include simply-supported beam bridges and continuous beam bridges. Compared with simply-supported beam bridges, continuous beam bridges have many advantages such as strong integrity, less beam joints, small fold angles, and high performance of flatness and smoothness of track. As a result, continuous beam bridges are greatly applied in high-speed railway. Due to the fully closed travelling of high-speed railway, the longitudinal and plane parameters of line are strictly restricted. And the high performance of flatness and smoothness of track is also requested. The smoothness of rail is influenced by the creep of prestressed concrete bridges. In order to ensure the smoothness of track, it is necessary to understand and control the creep deformation of bridges after laying ballastless track. Based on the four typical long-span prestressed concrete continuous beam bridges used on Wuhan-Guangzhou passenger special line, the paper gives an analysis on the impacts of post creep deformation of long-span prestressed concrete continuous beam bridges on high-speed train running performance. The main contents in the paper are as follows:(1) The creep deformation of four typical long-span prestressed concrete continuous beam bridges are calculated by finite element analysis. And the numerical results are compared with the measured data.(2) The dynamic models of the above four train-bridge systems are established by adopting a finite element method of box beam segments. The detailed calculation data are analyzed with dynamic simulation. The result indicates:the vibration responses of the above four train-bridge systems are within their permission values; the lateral and vertical maximum acceleration of car bodies are all in the range of allowable values; the safety, comfort and stability can be satisfied in the range of the design speeds.(3) The impacts of post creep deformation of the four long-span prestressed concrete continuous beam bridges on high-speed train running performance are analyzed. The result shows:when the high-speed train passes through the bridge, the creep deformations of the above four bridges have little effect on the dynamic response of bridges, and cause no apparent effect on the running performance of high-speed trains qualitatively. But numerical results show that the wheel load variance, the vertical vibration acceleration and vertical comfort index of high-speed trains will increase to a certain extent.(4) The reasonable values of post creep deformation of long-span prestressed concrete continuous beam bridges are analyzed. The results show that the 10mm creep deformation limit of ballasted track bridges could be relaxed in the provisions for design.(5) In summarization of the literatures and references about evaluation criteria on stiffness limit of railway bridges in domestic and abroad, suggestions are made for stiffness limit of long-span prestressed concrete continuous beam bridges on high-speed railway. The results provide a reference for design and construction of such kind of bridges.