Prestressed Reactive Powder Concrete Box Girder Optimization Study

Reactive Powder Concrete (RPC) is a newly-developed material, which has good mechanical property and high impermeability. At present, some passenger special railway lines and high-speed railways are under construction in China. RPC Structure has the advantage of light weight and good durability because of the high impermeability of RPC. Single-hole box girder, having been applied to Qin-Shen passenger special railway line, has advantages of resistance to torsion and big rigidity as well as good stability, etc. In order to make prestressed RPC single-hole box girder is applied well in practical engineering, this paper combines finite element analysis and optimization method to theoretically analyze RPC box-girders in passenger special railway line. The optimal parameters of cross-section and optimal prestressed RPC cross-sectional areas can be determined by optimization analysis and provide the reference for the practical application.The paper first takes 24m-span double-line railway prestressed RPC single-hole simply supported box-girder for an example, a finite element model included. The girder volume is taken as objective function, while the sectional dimensions of the box-girder and prestressed reinforcement area as design variables, under constraints of the strength and deflection, finite element parameter optimal analytical method fractical method is applied to optimally analyze the main working conditions of the box-girder's normal performance. The results indicate that the sectional height is the key deciding factor when the volume of prestressed RPC simply supported box-girder is optimal, prestressed reinforcement area is the key deciding factor of girder deflection.Based on the optimal parameter analysis, optimal calculation and analysis are performed on 24m-span and 32m-span double-line single-hole simply supported box-girder, and at last optimal sectional parameter and optimal prestressed reinforcement area of both spans are gained. During the analytical calculation, since the end cross-section of the RPC box-girder with constant section has well met the structural strength requirement, the common reinforced bar and the section only have to satisfy the structural requirements.