Rearch On The Creep Deflection Of Prestressed Concrete Girder Bridge

At present, main problem for prestressed concrete girder bridges in the world is excessive and durative deflection downwards at midspan. It's meaningful in theory and application to research the influence on long-term deflection caused by concerte creep and how to control it.Firstly, this thesis starts from the point of concrete creep, analyses the creep mechanism and various factors influencing concerte creep, creep theories and corresponding calculation methods. Except for those above, the differences in specifications for concrete creep are compared.Secondly, the Chongqing Changjiang River Bridge is reanalysed using finites element analyses software—MIDAS/CIVIL2006. The rationality of computation methods for concerte creep is discussed by comparing theoretical computation and actual data measured for years.Thirdly, pretressing, concrete creep and bending rigidity of box girder are studied to discuss their impacts on the deformation of girder. Current design theory and "Zero Moment Method" theory are introduced. The differences of two theories are compared by a bridge design case to enucleate the excellence of the "Zero Moment Method" theory.Lastly, this thesis introduces the construction control results for the Jiang'an Changjiang Highway Bridge.The parameters for prestress design and pre-camber of girder are discussed and improved parameters are suggested. The development and application of externally pretressing are introduced particularly. At last, the impact of externally pretressing on the control of girder deformation is explained.