Study On Acoustic Emission Characteristics Of Steel Strand Under Different Corrosion Degrees

In the development of construction industry in recent years,the steel strand has been widely used in bridge cable and prestressed anchor,playing an irreplaceable role in the field.The steel strand has high extension strength,and plays good in the relaxation performance.So at this stage of the development in bridge construction and slope supporting of rock anchorage,the steel strand plays an important role.As with ordinary steel,steel strand also can be corroded.The bearing capacity of steel strand in the service of the bridge and anchor stock will be greatly reduced.In order to reduce disasters in the practical engineering,it needs to conduct real-time monitoring on the steel strand to provide a reliable analysis on the actual situation of the project.The Acoustic Emission phenomena in the steel strand stretching process and failure point can reflect a lot of information about the internal damage of steel strand.Therefore,Acoustic Emission technology has great importance for the monitoring of building health and the stability of building components.In this text,the most commonly used steel strand is taken as research object,using the static tensile testing machine and DS2 AE testing analysis system of Beijing Island Time Inc to test the tensile strength of steel strand under different corrosion degrees.The Acoustic Emission characteristics are studied,and research results are listed as follows:(1)For simulating the actual situation of the chloride corrosion of bridge cable and anchor in the service period,the electrochemical corrosion tests were conducted to corrode the steel strand.Curves of the relation between corrosion rate and time were drew,and the effects of different corrosion degrees on tensile fracture characteristics and strength of steel strand were got.(2)Through uniaxial tensile AE tests,the Acoustic Emission parameters of the steel strand under different corrosion degrees and different loading rates were got,curves of the relation of AE parameters with time and stress were drew,and the influence of steel strand corrosion on the acoustic emission characteristics under uniaxial tension stress was summarized.(3)Through the analysis of the Acoustic Emission parameters of steel strand under different corrosion degrees,and spectral analysis in steel strand stretching process,we can learn the effect of different corrosion degrees and loading speed on the changes of steel strand frequency,so as to obtain the internal damage evolution trend.(4)Based on the micro research method of steel strand damage,we established the damage model of steel strand under different corrosion degrees according to AE cumulative ringing count,found out the relation curves between strain and damage variable,and established the stress strain damage constitutive model of tensile damage progress under different corrosion degrees.