Study On Structural Behavior Of Partially Prestressed High Strength Concrete Continuous Beam

With development and wide application of the steel fiber reinforced concrete (SFRC) and high-strength concrete, the fine physical and mechanical properties of SFRC and high-strength concrete has been the gradually recognized by many professionals. SFRC significantly improve the tensile properties, flexural behavior, impact resistance and fatigue performance of concrete, and has better ductility. The mechanical behavior, shrinkage and creep behavior, seepage resistance and abrasion resistance of high-strength concrete are significantly higher than those of normal concrete. It makes SFRC and high-strength concrete have potential advantage to cater to the tendency of high speed, heavy load and large span of modern railway and highway bridges.Based on the project of'The Struetural Behavior of Partially Prestressed High-Strength Conerete Variable Box-Section Continuous Beam', structural behavior of 6 pieces of two-span-contious-beam was studied in this dissertation, based on experimental and theoretical analysis.In this dissertation, the following aspects were selected as research subjects, which include constitutive behavior description of SFRC and high-strength concrete, mechanical analysis for partially prestressed high-strength conerete continuous beam, the cracking mechanism of SFRC, the limit state analysis of SFRC and partially prestressed concrete, and numerical simulation and nonlinear analysis of high strength SFRC continuous beam.In the first two chapters in this dissertation, the research history and the current state have been reviewed, and the constitutive model of concrete has been studied and investigated, and proper constitutive model has been established for the project, after summarizing the basic mechanical properties of SFRC and high-strength conncrete, based on existing results. In the third chapter, the design of the test beam, the main experimental results have been introduced, and the effect of PPR, steel fiber content and strength of concrete on structural behaviors of the test beams have been studied. In the following two chapters, the crack-controlling mechanism of SFRC, calculation method for crack-width and ultimate flexural capacity of SFRC member have been analyzed in detail, flexural behavior, redistribution of internal force and bending moment of partially prestressed concrete have also been studied.In the last chapters, the nonlinear analysis of test beams has been carried out by finite strip method. The proper strip model and calculation methods for presstressed box-section beam have been established, and the whole loading process has been successfully simulated. The experimental results and numerical analysis results have been comprehensively analyzed to provide foundation that can be refered for the application of partially prestressed high-strength concrete in bridge engineering.