Study On The Test Of Mechanical Properties Of Corroded Steel Strand

Corrosion cause degradation of mechanical properties of steel strands,it will seriously reduce the role of the steel strands in the structure,resulting in the durability failure of the prestressed structures.Based on the previous researches,this paper makes a research about mechanical properties of corroded steel strands from theoretical and experimental aspects.The main contents and conclusions of this paper include the following aspects.(1)Geometric and physical properties of steel strands are analyzed.The working principle of quick electrochemical corrosion and the principle of fiber grating sensor are introduced.(2)For Faraday formula is applied to ordinary steel limitations,19 groups of specimens were used to modify the Faraday formula,including different lengths of steel strands,different current densities,and the specimens were wrapped concrete.In the end,a correction factor is obtained to correct the Faraday formula.According to the modified formula,10 groups of specimens tensile tests are carried out,which results discrete is smaller than other authors.Data fitting resulting show that each mechanical property index is linearly dependent with corrosion rate.Finally,we observed the broken steel wire and found that: the higher the corrosion rate,the more prone to brittle fracture.(3)A new fiber Bragg grating sensor for measuring the corrosion rate of steel wire is designed,which is used to measure the corrosion of steel wire.The experimental results show that the method can get a good effect in the laboratory research,but if the fiber grating sensor is applied to the boom in the exposed test station,it will not effectively get the actual corrosion.(4)Based on the half-cell potential method working principle,experimental study of rust boom real-time monitoring are conducted,judging whether the boom is corroded and monitoring the corrosion changes of the cable force from the readings of the concrete corrosion tester.