Damage Detection Method For Cables Of Cable-stayed Bridge And Its Application

Cable-stayed bridge is one of the large span bridges which are very popular and widely used. Cable is the key component of cable-stayed bridge. Once a cable is damaged, the loss of its carrying capacity will have great influence on the entire bridge and may even lead to collapse of the whole bridge. Therefore, studying damage detection method for cables is of great significance. At present, researchers are in-depth study of cable damage identification from multiple angles. Though, there are some achievements, but most of the methods lack baseline which judge structural damage and represent structure in good condition. Thus, it is difficult to apply them in engineering practice. Musical tone law method and symmetrical signal method, which are suitable for cable damage detection, were introduced in this paper. Cable model test was done to verify effectiveness of musical tone law method and vibration testing was conducted on the cables of Song Yuan Bridge to verify effectiveness of symmetrical signal method. The main tasks can be summarized as follows:1. A steel cable was chosen as test subject, musical tone law method was used in the damage detection of the cable. Model test result proved that natural frequency distribution and spectrum of healthy cable to meet the characteristics of musical tone law, namely the natural frequencies distribute regularly and the shape of the spectrum line is like a comb;. In the damage detection test of steel cable, the frequency difference is used as diagnosis index in structural damage detection, and the damage is detected successfully.2. Vibration testing was conducted on the cables of Song Yuan Bridge to verify effectiveness of symmetrical signal method. The test results show that natural frequencies of the two mutually symmetrical cables are almost equal. This reflects the basic principle of symmetrical signal method, namely modal information of symmetric component such as frequency should be equal; Natural frequency which was chosen as the cable damage diagnosis index has a strong environment interference resistance.