Study On Prestressed Concrete Continuous Box Girder Bridge Under The Influence Of Steel Strand Corrosion

Prestressed concrete bridge has a long history.So far,a large number of prestressed concrete bridges have been built around the world.With the increase of service life,the corrosion problems of steel strand of these bridges has become inevitable.How to avoid corrosion of bridges has become a global problem.The difference of corrosion degree and the randomness of the corrosion location of the bridge,has become the uncertain factor influencing the performance of corrosive bridge.In this paper,from the aspect of chloride corrosion of steel strand,theoretical analysis,experimental research and structural finite element simulation analysis are carried out.The time-varying theory of corroded steel strand and the mechanical properties of prestressed concrete continuous box girder bridge are further studied.In this paper,the literature related corrosion of steel strands and analysis of corrosive bridge are reviewed.Base on existing research results,researches has been carried out.The main contents and results are as follows:(1)The corrosion mechanism of the steel strand and the corroding cause of the steel strand of the box girder are summarized,and the theoretical guidance is provided for the study of the corrosion of the steel strand of the prestressed concrete continuous box girder from macroscopic and microscopic.(2)The time-varying model of corroded steel strand is stduied,and the time-varying theoretical model is updated and optimized.The time-varying model of mechanical properties of steel strand has been and put forward.The theoretical model of timevaring loss of prestressing force is applied and analyzed.(3)The corrosion morphology and mechanical properties of the steel strand were tested,and the morphology of the corrosion and the tensile fracture of the steel strand were summarized,and the mechanical properties based on the corrosion rate were proposed.The main mechanical properties of steel strand has a nonlinear relationship has been demonstrated by experiment.When the corrosion rate of steel strand is less than 10%,the simplified model of model steel strand has better applicability.(4)According to the mechanical properties of the steel strands obtained by the test and the area degradation model of corroded steel strand,a further improved classification standard for the steel strand corrosion and the corrosion grade of the steel strand are put forward.Based on this,the corrosion condition of prestressed concrete continuous box girder is determined.(5)Base on the prestressed concrete continuous box girder under different corrosion conditions,the finite element analysis is carried out with ANSYS to study the internal force,deformation and damage form of the prestressed concrete continuous box under different corrosion conditions.The stress,deflection,stress,failure form and failure position of the prestressed concrete continuous box girder are compared under various corrosion conditions.(6)The response surface method is used for reliability of random finite element analysis,and the results are compared with the results of time-varying reliability analysis.