Long Term Deflection Analysis On The Long Span Prestressed Concrete Continuous Rigid Frame Bridge

Due to the advantages of reasonable force, convenient construction, comfort and comfortable driving, long structural rigidity and good overall performance, long span prestressed concrete continuous rigid frame bridges have been widely used in our long-span bridges. Taking Zidongte Bridge as the engineering background, this paper makes calculation and analysis on the influencing factors for the long term deflection in long span continuous rigid frame bridges. Main contents in the paper are as follows:(1) This paper introduced the current development and trends on long span prestressed concrete continuous rigid frame bridges, as well as the research status of the deflection problem of the long span continuous rigid frame bridges at home and abroad.(2) This paper introduced the project profile and operational situation of Zidongte Bridge. The finite element analysis model of the bridge was built, the bridge deflection was calculated and the characteristics on the long span bridges were analyzed.(3) The analysis on the prestressing loss’ s impact on the long-term deflection was made, so as the friction loss parameter μ. K’s impacts on the long-term deflection and the losses for the top and baseboard prestressing.(4) The paper described the mechanism of creep and shrinkage, as well as the prediction model at home and abroad, the creep and shrinkage’s impacts on the long-term deflection were also analyzed and compared.(5) By the web crack in the box girder, this paper respectively explored the different degrees of reduction in the box girder’s segmental stiffness, the stiffness in local areas and the stiffness of the entire bridge to analyze the impacts on the deflection of continuous rigid frame bridges.(6) A further analysis was also made on the impacts from factors of the beam height, the number of prestressing steel, the shear deformation and operational period on the deflection of continuous rigid frame bridges.(7) For the issue of excessive down deflection in the span of Zidongte Bridge, different combinations of calculation and analysis on this several influencing factors were made, thus to discuss the reason resulting in the excessive down deflection for the bridge. A further analysis on the effect of reducing the deflection was made by changing the design parameters of this bridge.