Fundamental frequency identification method for detecting cord force of cable-stayed bridge

Abstract

The invention discloses an identification method of fundamental frequency for detection of the force of the cable of a stayed-cable bridge, which gets a first fundamental frequency by an autopower spectrum module, a second fundamental frequency by a cepstrum module, and then determines whether the quotient of the following two values is less than or equal to the set threshold: 1. the absolute value of the difference of the first fundamental frequency and the second fundamental frequency; 2. a half of the sum of the first fundamental frequency and the second fundamental frequency. In this way, whether the fundamental frequency of the pull cable is a half of the first fundamental frequency and the second fundamental frequency is determined. By adopting the method, the accuracy and the precision of the fundamental frequencies got are significantly improved. In addition, as the vibration acceleration response time interval signal got by an acceleration sensor passes through a signal conditioning module for filtration and smooth processing firstly, the environmental noise in the vibration acceleration response time interval signal is effectively suppressed; the antijamming capability of the stayed-cable bridge is improved so that the fundamental frequency is identified more clearly and accurately.

Description

technical field [0001] The invention relates to a cable force detection method, in particular to a fundamental frequency identification method for cable force detection of a cable-stayed bridge. Background technique [0002] The cable system is an important load-bearing component of the cable-stayed bridge. The random vibration caused by the cable system under the dynamic load of the bridge and the wind and rain will cause the fatigue damage of the cable, reduce the fatigue life of the cable, and seriously affect the safety of the bridge. run. At present, the self-power spectrum method based on environmental vibration is usually used in the measurement methods of cable force monitoring and state assessment of cable-stayed bridges. The key is to accurately identify the fundamental frequency of cable-stayed bridge cables under different conditions. This method is mainly based on T = 4 ρ L 2 ...

AI Technical Summary

Problems solved by technology

[0002] The cable system is an important load-bearing component of the cable-stayed bridge. The random vibration caused by the cable system under the dynamic load of the bridge and the wind and rain will cause the fatigue damage of the cable, reduce the fatigue life of the cable, and seriously affect the safety of the bridge. run

At present, the self-power spectrum method based on environmental vibration is usually used in the measurement methods of cable force monitoring and state assessment of cable-stayed bridges. The key is to accurately identify the fundamental frequency of cable-stayed bridge cables under different conditions. This method is mainly based on T = 4 ρ L 2 f 1 2 In the formula, the cable force T and the fundamental frequency f 1 The relationship between the cable-stayed bridge cables, through the self-power spectrum analysis of the cable random vibration signals picked up by the acceleration sensor installed on the cables of the cable-stayed bridge, the fundamental frequency f of the cable vibration signals is obtained 1 Finally, the cable force is calculated, so as to judge the safety performance of the cable-stayed bridge according to the cable force. However, due to the randomness and variability of the environmental vibration, the real peak of the power spectrum is not easy to identify, and the fundamental frequency of the cable is very low. And the low-frequency band of the power spectrum is often coupled with the fundamental frequency of the bridge deck or bridge tower, resulting in fuzzy recognition of the fundamental frequency and low accuracy of cable force detection.

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