Research And Application For Low Slenderness Ratio Cable’s Tention Monitoring Based On Multistage Frequency Fitting Method

Cable force monitoring has become an important part of the bridge health monitoring, accurate thecompleted information for construction monitoring, into a bridge acceptance, operation management,scientific maintenance to provide direct basis.Now there is a kind of high efficient, economic andconvenient cable force test method is based on the theory of string model of the measured line of bodyvibration frequency identification method. But in practical application, for the44mm diameter or greater,the short length diameter ratio of100or less, by boundary constraints, the overall stiffness, the influence ofthis method is difficult to accurately monitor.For the lack of this project,based on the single pyloncable-stayed bridge without back cable, and the cable force monitoring is a research background. Mainlycarried out research on multi-stage frequency fitting method,to recognite cable force in the cable forcemonitoring. Work content is as follows:（1）Using the numerical analysis and calculation, based on the vibration theory, Considering theinfluence of different boundary conditions and cable stiffness, the single cable vibration frequency is usedto numerically solving transcendental equation. Thus fitting out of the cable force under different boundaryconditions on the vibration frequency of practical calculation formula, as a reference formula of practicalapplication.（2）Cable vibration model is established, according to various scale short cable under different cableforce of vibration test, using fast Fourier transform and spectrum analysis for lanyard, multistage frequency.So based on the test results more order frequency optimization of cable force calculation formula offitting.Monitoring results show that it has a high monitoring accuracy and applicability, and can solve thechunky cable force monitoring by the boundary constraint condition and the problem of the cable stiffness.（3）The establishment of a cable dynamic characteristics test platform: Combined with a single towercable stayed bridge without back features cable, combined the engineering practical experience, based onthe research of the various performance parameters of the sensor subsystem, put forward of sensor,acquisition equipment, vibration device and monitoring software such as power to choose the optimal testplatform.（4）Using the method of multistage frequency optimization fitting cable force monitoring, the baojisingle pylon cable-stayed bridge without back cable construction process of monitoring in theprocess.Practical formula and multistage frequency fitting formula according to the results of monitoringthe completed as follows:①nearly10%error may arise when the cable force is small, but by calculation,using high order frequency other than the fundamental frequency calculation, still can get ideal effect;②the cable force is not very low, the practical formula of fitting can meet the need of engineering precision,error can be controlled within3%. So validation based on multistage frequency optimization fitting cableforce monitoring method feasibility and the accuracy, security implementation of this project plays aguiding role, and the project of the same type of cable force monitoring for reference.