Research On The Girder's Deflection Of Long-Span Prestressing Concrete Continuous Girder Bridges

With the development of science technology and traffic enterprice the long-span continuous girder (rigid frame) bridge has been growing up rapidly in the recent years with it's unique predominance of handy construction,economical cost,reasonable interal force and comfortable traveling. But the theories and experience in it are not very perfect because of it's short appearance. There are still several questions in the construction. In prestressed concrete structures, they are important to know how much the prestress losses is and estimate the creep exactly for the deflection of the structures. Therefore, the prestress losses and the creep are the main reasons why the deflection of the girder is larger than that of code.Prestress loss perspective is started in the thesis, the breakdown for the losses of prestressed long-cables, longitudinal prestressing losses and vertical prestress losses from the theoretical analysis and exposition of their impact on the main beam deformation. The second step from the perspective of creep, creep through the mechanism and the factors affecting the creep, creep theory and the calculation method still early strength with the addition of a corresponding analysis of the study concluded. Midas bridge structure analysis software to create a real bridge model, the model sensitivity analysis done on various factors, and analyze the results of sensitivity analysis compared judge finally selected secondary factor.In addition, the exposition of this thesis is innovative in two ways. One consideration : the creep calculation considering live-load. Previous calculated when considering the dead-load creep of concrete containing its impact, but as the economy develops, the bridge traffic will increase, having been made substantial live load in the loading bridges in days and nights, the live-load creep therefore should not be overlooked; Second : the impact of adding hardening accelerating admixture into concrete. To speed up the progress of the construction unit, general ly add hardening accelerating admixture into concrete . However, only concrete strength is rapidly increasing, and the modulus of elasticity of concrete is not with a corresponding increase when the hardening accelerating admixture added.