Research On A Damage Identification Method For Stay Cables Of Long-span Cable-stayed Bridges Based On Cable Force Monitoring

Aiming at the health problems of stay cables of long-span cable-stayed bridges,Jembatan Suramadu(S-bridge for short)is selected as the specific research object.The finite element model of the S-bridge has been established.Based on the cable force monitoring,the damage identification results using the linear relationship hypothesis are statistically analyzed,and a new damage identification method with higher accuracy is proposed,and the feasibility of this damage identification method for cable-stayed bridge cables is studied and verified.The main works in this dissertation can be concluded as follows:Firstly,based on the finite element model of the s-bridge under the condition of cable force monitoring,a statistical analysis of the damage identification results is carried out using the linear relationship hypothesis theory.According to the recognition result,it is found that there is a case of erroneously identifying the damaged cable.Secondly,for the calculation examples with errors,a “preliminary optimization algorithm”using iterative method is proposed,which is called “Identification Method I for the Health Status of Stay Cables”(referred to as: Identification Method I).The method obtains a new unit damage vector for the next iteration based on the difference between the calculated cable force at the end of each iteration and the actual cable force value.This method is used to identify damage to the errored example in order to achieve better identification results.At the same time check whether the good examples in the original recognition result are still good.During this process,observe and analyze the recognition results and find the deficiencies of the algorithm as a basis for further correction.Third,on the basis of discovering the deficiency of “Identification Method I”,iterative method was used to further improve “Identification Method I”,and a new revised identification method was proposed,namely,“Identification Method II for the Health Status of Stay Cables”(referred to as: Identification Method II).Compared with "Identification Method I",the selection method of unit damage vector is further revised.This method is based on the difference between the calculated cable force and the actual cable force value at the end of the current iteration and the previous iteration,and the unit damage vector used for the next iteration is obtained through calculations in different situations.And this method is used to identify damage to the errored example in order to achieve better identification results.At the same time check whether the good examples in the original recognition result are still good.During this process,observe and analyze the recognition results to examine the feasibility of this method.Finally,the two optimization algorithms are compared from the aspects of cable force,identification results,statistics of results,etc,and a method for identifying the health status of cable-stayed cables with higher accuracy is selected.The research shows that on the basis of the linear relationship between the cable force and the damage degree of the stay cable,the“Identification Method II” using the iterative method can more accurately identify the damaged cable and the damage degree.