Key Technology Research For External Prestressing Strengthen In Reinforced Concrete Thin-wall Box Girder

Thin-walled concrete box girder structure due to its many advantages, can be widely used in recent years in long-span bridges. But at home and abroad to build a thin-walled box girder bridge box girder with varying degrees of widespread cracking and the phenomenon of cross-Deflection after completion. Cracking under torsion beam and also influence each other, resulting in a vicious cycle, seriously affect the performance of the bridge. External prestressing reinforcement is a positive reinforcement of effective proactive approach can improve the carrying capacity of the structure, improving inter-state and Deflection girder compressive stress increases reserves, is one of the preferred method of thin-walled box girder bridge reinforcement. Although external prestressing reinforcement method has a lot of applications, but there are still many issues to be further studied. In this paper are to do some research on the following questions:This paper studies the concrete girder bridge with thin main diseases and their causes; girder bridge with thin crack and impact factors and Treatment Measures under torsion analysis; externally prestressed concrete girder bridge with thin reinforced structural arrangement and optimization of cable force reinforcement affect the results, combined with research support projects to determine the main diseases produce and the simulation of bridge disease, then this is a reasonable basis reinforcement scheme and to determine its overall reinforcement effect.The main contents include:â‘  by collecting a large number of thin-walled box girder bridge data, summarize its main disease, and preliminary analysis of its causes;â‘¡ combined engineering background, using the finite element analysis software for simulation, analysis of the roof and floor, web and vertical prestress losses, beam cracking, weight increase, shrinkage and creep effect on the thin-walled box girder bridge Crack and Deflection of impact, finding the main factors causing disease girder bridge with thin, pre-fitted model background reinforcement;â‘¢ for external prestressing reinforcement cable force optimization and steering block more rational layout scheme study obtained a more rational optimization and external prestressing reinforcement technology, and through this project examples reinforcement technology to be verified;â‘£ external prestressing reinforcement engineering background combined with practical engineering solutions, analysis and calculation of its reinforcement effect. At the same time based on results of this study on the basis of external prestressing reinforcement on key technologies, to design a new project for background reinforcement scheme, have also been calculated and analyzed its reinforcement effect. New contrast, differences between the old two Reinforcement reinforcement effect, combined with the actual bridge strengthening program reinforced the overall situation after the bridge, on the external prestressing reinforcement technology proposed for evaluation.Research results are confirmed by the analysis of the project, and the effect is good.