Research On Creep And Shrinkage Mechanism Analysis Of High-Speed Railway Long-span PC Continuous Beam Bridge

Creep is one of the material properties of concrete by which constructions continue deforming over considerable lengths of time at constant stresses or loads. If the load were maintained, the deformation would increase to several times its elastic value. Creep brings not only on deformation, but also redistributions of stresses and losses of prestress. The influence of creep on bridge structures is especially severe. The calculation of creep has become necessary in bridge design and construction.Especially the high-speed railway construction has already begun the prologue. Jinghu high -speed railway construction has also been in the brewing. The enhancement of train's running speed needs a higher request to the track regularity. After speed-up, regardless of reinforced the existing bridges or newly built prestressed concrete bridges, the control of the bridge long-term deformation has become one of the most important principles of design.Taked the Lu Shui super-large bridge on the passenger transportation dedicated line from Wuhan to Guangzhou with its main span of 125m as the research background, the impacts of shrinkage and creep caused to the long-span high-speed railway bridge are analyzed to get its general rules, and the computation and analysis basis for later similar bridges is provided.First, the systematical generalization of the development of shrinkage and creep inland and abroad, the mechanics of the concrete shrinkage and creep, and the internal and external factors affected the concrete shrinkage and creep are made. Then partial factors, applicability and merits and faults of shrinkage and creep prediction mode on several kinds of frequently-used mechanisms inland and abroad are compared and analyzed, establishing the basement of proper selection of prediction mode in the analysis of shrinkage and creep effect of practical structure.Then three models of the shrinkage and creep of concrete (CEB-FIP1978,CEB-FIP1990,ACI209)are separately selected and emulated. According to the analysis and comparison of pavement sensibility of land water especially big bridge, the best paving time is got. Afterwards, the partial factors affected the shrinkage and creep in CEB-FIP1978 model just as the relative humidity, the load stadium and the prestressing force are analyzed, then the proper theories of the best concrete age of loading and initial pressure are got, providing the basis for the practical project.