Ballastless Track Of Large-span Prestressed Concrete Continuous Beam Bridge Late Creep Deformation

Amount laying of ballastless track on high speed railway has become trend. It is very difficult to ensure the smoothness of the track because the height of the track can be adjusted little without ballast. Therefore, it is necessary to know and control the creep deformation of concrete bridges after laying track, namely post creep deformation. According to the mechanism of shrinkage and creep, the influences factors of shrinkage and creep, the calculation of creep coefficients, the basic methods of shrinkage and creep the post creep deformation of a long span prestressed concrete continuous beam bridge which is on Guangzhou to Zhuhai intercity rail traffic engineering has been calculated. The major work of this paper is as follows:1. The calculated creep coefficients according to the formularies in the several current codes were compared with the measured values. The results showed that the creep coefficients of Chinese Railway 05 Code and Chinese Highway 04 Code are both greater than the measured values.2.Several basic theories and methods of creep calculation were analyzed, and some research was done on the methods of creep calculation of prestressed concrete structure, and the calculation function of creep deformation of currently common used softwares were researched comparatively. There are much difference in the calculation of creep and the processing of prestress among different softwares.3. Considering the construction process and the system transformation, the post creep deformation of an ( 85+135+85 ) m prestressed concrete continuous beam bridge was analyzed according to different codes . The results of Chinese Railway 05 Code are two times greater than those of Chinese Highway 04 Code.4. Influence factors of post creep deformation of long span prestressed concrete continuous beam bridge with ballastless track were analyzed, and some methods were proposed to reduce later creep deformation. The results showed that creep and prestress loss has more effect than shrinkage in later creep deformation of long span prestressed concrete continuous beam bridges. We can reduce later creep deformation of long span prestressed concrete continuous beam bridges by adjusting closure time, laying secondary dead load time, the order of laying secondary dead load and top and middle steel strands in mid-span.The calculation results of this paper provides basic for the design and construction of the bridge. Meanwhile, it can provide reference for later creep deformation calculation and control of other same type bridges.