Model Test Study On Mechanical Property Influence Of Steel Strand Corrosion On Prestressed Concrete Beam Bridge

The infrastructure construction of China is on the highway to a flourishing period of development in the last 20 years,while the prestressing technique being widely applied.Durability problems have appeared on some of the completed engineering structures with a period of engineering construction not being considered long yet.Referring to the durability failure problems of prestressed concrete structure,we can easily tell the obvious difference between the failure mode and the modes of other types of structure.There's no sign for the failure of most prestressed concrete structure which is considered a sudden brittle fracture occurring in the safe working conditions,instead of visible cracks,large deflections and good ductility of ordinary reinforced concrete structure.Prestressed concrete structures are generally important projects in China,and if they fail in the absence of signs,as a consequence,the public will suffer huge losses and bad effects.It's found that the failure of prestressed concrete structure is due to the corrosion of steel strand.Consequently some research on strand corrosion of prestressed concrete structure have been done by domestic and foreign scholars,and despite the fact that majority research is still at the start stage at present.As part of the Science and Technology Education Project of Yunnan Communication Department,this paper studies the influence of steel strand corrosion on the mechanical properties of prestressed concrete girder bridge.The main research contents are as follows:1.This paper analyzes and studies the grade of steel strand,putting forward a method of evaluating the grade of corrosion degree of steel strand,and obtaining the classification and grading standard table of corrosion degree of steel strand by calculating.2.Through the design of the test beam body and the design of the test process loading,the static load test of the prestressed concrete test beam in different corrosion degree is carried out,obtaining the failure form of beam,and the comparative analysis results of the deflection at different corrosion rate,steel bar,steel strand strain and cross section of concrete strain in the case of local corrosion.3.Owing to the analysis of corroded prestressed concrete beam by means of thefinite element software FEA,the failure form of the beam body and distribution of fracture is obtained.It manages to verify the calculation accuracy of the finite element mode by analyzing and comparing load value and maximum deflection of every stage with the experimental results in various corrosion degrees.4.Based on the analysis model of time-dependent reliability which aimed at the reliability analysis of reduction of the bearing capacity of the girder bridge caused by the corrosion of steel strand,the time-dependent reliability index of the flexural capacity of a 3×40m prestressed concrete continuous T-beam bridge is calculated.Compared with the reliability of target value,the failure time of the bridge and the failure corrosion rate of the strand are derived eventually.