Research On Self Calibration Technology Of Measuring Cable Force With Fiber Bragg Grating Sensing Technology

Bridge cable is the most important and vulnerable structural component in the bridge superstructure.As an important stress component in the structure,in the bridge structure,the cable force affects the internal force distribution and linear change of the whole building structure system.In the cable system,any abnormal change of the cable force will affect the stability and safety of the whole structure.Therefore,in the actual project,the real-time monitoring of the cable force of the bridge and the accurate measurement of its cable force value are of great significance for the safety construction and operation of the bridge to evaluate the health of the bridge.At present,the commonly used cable force monitoring methods at home and abroad mainly include pressure gauge measurement,pressure sensor measurement,vibration method,magnetic flux method,but there are always problems in practical application,such as large measurement data error,measurement inconvenience and so on.Therefore,on the basis of previous studies,this paper has carried out further research,the main work is as follows:(1)Referring to a large number of relevant literature on the measurement of bridge cable force,this paper analyzes the previous research work,analyzes the advantages and disadvantages of various measurement methods,summarizes the research results of fiber Bragg grating sensing technology at home and abroad,and summarizes the research status of vibration measurement of bridge cable force at home and abroad,and on this basis,puts forward its own research content.(2)This paper introduces the basic principle of vibration method and strain method to measure the cable tension of bridge beam in detail.Combining the advantages and disadvantages of these two methods and the fiber Bragg grating sensing technology,the self calibration technology of cable tension is proposed,and the theory of self calibration technology of cable tension is introduced in detail.(3)Prestressed steel strand cable for central wire coupled fiber Bragg grating sensor in constant temperature laboratory Through the analysis of the test data,it is found that under the constant temperature laboratory conditions,the error between the measurement results of the cable force self calibration technology and the actual tension value is only within ± 5%.(4)Through the field cable force measurement of the bridge cable of Shengtian bridge in Yiyang,the accuracy and accuracy of the cable force measurement in the actual project are further verified.The test results show that: 1)the cable force values obtained by the frequency method and the strain method are relatively close,so the values corrected by the self calibration technology will be closer to the real value of the bridge cable Force.2)Four FBGs of FBG type cable force sensor do not affect each other by the method of parallel connection.It is found that the FBG sensor is damaged in the use process,which can be replaced to realize replaceable and sustainable use,and further extend the durability of FBG sensor.