| The prestressed structure has excellent performances such as improving structural bearing capacity and crack resistance.At present,prestressed structures are widely used in important infrastructure such as nuclear facilities and long-span bridges.With the widespread application of prestressed structures,some common diseases have also emerged.Prestress loss,prestress corrosion and other issues threaten the safe operation of the structure.Due to the complexity and variability of the operating environment,the different structural styles and the difference in upper acting loads have made it difficult to perform structural health testing of prestressed structures.It can be said that environmental impacts have an important impact on the detection of effective prestressing.At present,prestress detection is a worldwide problem,and corrosion as a common disease has an important impact on the accuracy of the stress detection results of prestressed tendons.At the same time,once the steel strand in service is corroded,prestress loss and stress corrosion will occur,which seriously affects the safe operation of the prestressed structure.Based on the detection of the prestress of the steel strand based on the LC electromagnetic resonance circuit,this study successfully applied it to the corrosion rate detection of the steel strand,laying the foundation for the non-destructive detection of the health status of the steel strand in the active structure.In this system,the stranded wire is regarded as an external inductor embedded in the LC resonance circuit.After the stranded wire is corroded,its electromagnetic characteristics will change,and this change will be reflected by the resonance frequency~f.Based on the above rules,this article has carried out four aspects of research work.(1)This article expounds the regular change of the resonance frequency caused by the change of the inductance of the steel wire after corrosion in a theoretical perspective,and establishes a theoretical model of the relationship between the electromagnetic resonance frequency and the corrosion rate.(2)The experiment proves that the overall corrosion degree of bare steel stranded wire can be accurately detected based on the LC electromagnetic resonance method,and a fitting formula for the corrosion detection of steel stranded wire is established.Through the analysis and investigation of the test data and test phenomena,it is found that the inductance of the steel strand decreases with the increase of the corrosion rate,which causes the resonance frequency to increase.(3)Based on the previous team research,a model of the relationship between the electromagnetic resonance frequency and the stress of the corroded short steel strands was established.The influence of corrosion on the model of the electromagnetic resonance frequency and stress of steel strands was analyzed theoretically.(4)The effect of corrosion on the model of the relationship between the resonance frequency and the stress of short steel strands was verified through experiments.Compared with the force-frequency relationship of uncorroded steel strands,the test found that different corrosion rates have an effect on the stress The effect of its resonance frequency.Through experimental verification and data analysis,it is found that as the corrosion rate increases,the inductance of the steel strand after corrosion decreases,which causes the resonance frequency of the steel strand to increase at the resonance frequency.In the tensile test of corroded short steel strands,the researchers found that under the same stress state,the resonance frequency of the steel strand will increase with the increase of the corrosion rate.This rule is the same as that of the steel strand under no stress.Consistent in corrosion detection studies.From this we can conclude that the larger the resonance frequency of the steel strand of the same length in the prestressed structure,the greater the corrosion rate. |
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