Research On Shrinkage And Creep Effect For High-pier & Long-span Continuous Rigid-frame Bridges

Shrinkage and creep are the inherent time-dependent characters of concrete which belongs to a viscoelastic material. High-pier and Long-span continuous rigid-frame bridges are sensitive to shrinkage and creep. Large error with respect to the predication of shrinkage and creep would lead to some problems of closure segments quality of cantilever constructing bridges, and lead to some problems of linetype, aesthetics, normal serviceable and eventually early reconstruction of the bridges. It is important to accurately estimate and predicate the deformation and stress of high-pier and long-span bridges which arise from the effect of shrinkage and creep for engineering construction and control.The major jobs of the paper are as follows:First, based on extensive collection of the research data about shrinkage and creep at home and abroad, the shrinkage and creep mechanism, influencing factors, some common calculation theories, methods and predication models were summarized and the mechanism, factors considerd, application scope and so on of the several common domestic and forign predication models were compared and analyzed.Then take Longtan River bridge as the engineering background, plenty of datas about deflection and stress of the bridge were measured on site. Then establishing finite element model with the professional software--MIDAS/Civil, the simulation analysis was carried out based on Code for Design Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTJ023-85 and JTG D62-2004, then the calculation results and the field measured results were compared.The analysis results shown that the shrinkage and creep prediction based on the latter was more accurate and more suitable for the actual situation. At the same time, the predication for deflection and stress of the bridge was made when it was under operation. It can offer useful help for bridge maintenance and care.Finally, the theoretical analysis about the prestress loss which caused by shrinkage and creep was carried out based on Code for Design Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTJ023-85 and JTG D62-2004. The analysis results shown that the predication trends of prestress loss based on the two different codes were basically identical, but the predication result of the former was smaller than the predication result of the latter.