Abnormal Cable Force Detection And Damage Identification Of Cable Stayed Bridge

The bridge health monitoring system monitors the operating conditions of the bridge around the clock,collects structural response data under the normal operating state of the bridge,and provides basis and guidance for the maintenance and state warning of the bridge.Cablestayed cables are the main load-bearing components of cable-stayed bridges,and they are also weak links.They are prone to damage such as corrosion,broken wires,and fatigue,which adversely affect the operation of cable-stayed bridges.The cable tension is an important monitoring item of the cable-stayed bridge health monitoring system.How to use the monitoring data to evaluate the cable working status and realize the bridge safety warning is a research hotspot at home and abroad.This research is based on the Hengyang Dongzhou Xiangjiang Bridge Cable Force Monitoring Project as the background,and the long-term monitoring and condition assessment of the cable force are studied.The main research contents are as follows:(1)Trend analysis of cable force monitoring data.Analyzing the change trend of a large number of cable force monitoring data,studying the correlation between cable force and temperature,it is found that the cable force will show periodic changes with the temperature difference between day and night,and will also show long-term increase or decrease with the change of seasons.(2)Abnormal detection of cable force monitoring data.For on-line real-time detection and periodic detection of cable force,a method for detecting anomalous cable force based on the ratio of length to short time and a method for detecting anomaly cable force based on empirical mode decomposition are established respectively.Anomaly detection analysis found that both methods can detect the actual abnormal points of the cable force monitoring data.For the cable force abnormal data with a deviation of more than 2%,the detection success rate is basically the same.For the abnormal data with a deviation of less than 1%,the experience model The state decomposition method has a higher detection success rate.(3)Cable force trend prediction and main beam damage identification.Use the cable force monitoring data to establish the ARMA model,and use the iterative method to predict the cable force trend in the next three days.The results show that the predicted data are in good agreement with the measured data;the finite element software is used to simulate different damages to the main girder of the cable-stayed bridge Under working conditions,an ARMA model based on acceleration data is established to identify damage.The results show that the first three-order AR coefficients of the model are related to the degree of damage and can be used as damage identification indicators.(4)Develop abnormal cable force monitoring and early warning software.In order to facilitate cable-stayed bridge managers to monitor and maintain the bridge,based on the MVC technology framework,using PHP and SQL languages,the proposed method for detecting cable force anomalies is implemented in Web application software.The software has a friendly interface,high practicability,and can be competent for cable force in the task of monitoring and early warning.