Research On Damage Identification Of Bridge Structure Based On Dynamic Characteristics

In recent years,with the rapid development of the national economy,while the number of newly built bridges is increasing,the existing bridges are affected by environmental,climatic and other factors for a long time,combined with the effects of dynamic and static loads and sudden natural disasters and man-made damage.Its own strength and rigidity are also constantly decreasing,and various injuries are also generated,which brings great hidden dangers to bridge safety.Therefore,the damage identification of bridge structures has become a research direction that is increasingly valued by experts and scholars.The Kalman filtering method is used for bridge damage identification based on detection data because of its ability to remove noise interference.However,the current research is mainly limited to theoretical simulation,and experimental research needs to be strengthened.For this reason,the Kalman filtering method is tested and improved by the indoor test of steel truss bridge.The damage identification method based on structural frequency and vibration mode test information is studied.The main research contents and conclusions are as follows:(1)In order to simulate the structural damage and noise interference that may occur in the actual environment of the steel truss bridge,various working conditions are designed to make the test more realistic.(2)For the case of no noise interference,whether the steel truss bridge contains additional fulcrum constraints,the frequency response function is used to extract the frequency and shape data of the structure,the structural mode is obtained by the displacement mode method,and then based on the structural vibration.The combination of type and frequency can accurately judge the position of different damages of the structure.(3)Try to combine the structural frequency response function with the Kalman filtering method.For the measured acceleration with noise,first perform denoising processing to improve the accuracy of the measured value,and then perform damage identification to accurately identify the location of the damage.(4)The attenuation Kalman filtering technique used to track the target trajectory in the aerospace field is introduced into the parameter identification of the bridge structure.A four-span continuous beam bridge is taken as an example for simulation analysis,and the rough value of its physical parameters is taken as the observation vector.The iterative equation of extended Kalman filter is established,and then the forgetting factor is introduced to reduce the influence of the old observation data on the filtered value,so that the more accurate structural physical parameter values are obtained.(5)The attenuation memory filtering method is applied to the processing of the measured acceleration signal with noise.By comparing the structural frequency values obtained by adding the forgetting factor before and after the operation,it is found that the attenuation memory filtering method has better denoising ability than the Kalman filter.