Flexural Behavior Study On Prestressed Concrete Continuous Beams

Many Studies have been made on flexural behavior of prestressed concrete continuous beams, but some aspects of this structure are still not clear, especially the study on the influence of the construction method on the internal force redistribution hasn' t been carried out. In this paper, a systematic overview of the current study on the prestressed concrete continuous beams is made first; then the study on the model tests and the nonlinear analysis have been made, and the simplified calculating method has been developed as well.In order to investigate the flexural behavior, ultimate bearing state and internal force redistribution of prestressed concrete continuous beams with different construction methods, three 3-span model beams have been tested with the medium span which is widely applied in Chinese highways as the prototype girders. These tests provide basis for studying the nonlinear analysis approach and the simplified calculating method of prestressed concrete continuous beams, and also enrich testing achievements of prestressed concrete continuous beams.Through the analysis on the material properties and stress mechanism of prestressed concrete continuous beams, a complete whole process analysis has been carried out. The result shows that the nonlinear finite element theory and method is effective and feasible.Then, using nonlinear finite element program, parameter analysis is carried out to study the effect to ultimate capacity and bending moment redistribution, such as stress of prestressed tendons, Partially Prestressing Rate(PPR), Degree of Prestressing(DP), reinforcement index and construction method. It is indicated that PPR, reinforcement index in compressed area and construction method are the main factor to bending moment redistribution. The increase of the Partially Prestressing Rate and the reinforcement index in compressed area will result in the increase of the bending moment redistribution. The beam with cantilever construction has the maximal bending moment redistribution, the beam with construction method of simply supported-to continuous has the minimum bending moment redistribution. The bending moment redistribution of structures with different construction methods will contribute to the similar ultimate bearing capacity.Last, on the basis of the finite element analysis and the regression analysis, the simplified calculating formula is obtained. Adopting elastic analysis, elastic analysis with bending moment redistribution, spacial nonlinear finite element analysis, the ultimate load is caculated. The comparison with other testing results and calculating methods indicates that the formulas of this paper.are reliable and practicable.