Research On Damage Identification Method Of Bridge Under Vehicle Excitation

Bridges under the influence of vehicle loads,wind loads and environmental natural disasters,will lead to the deterioration of components,and the bridge structure will occur deterioration in performance.Bridge is the key hub of transportation engineering.And long term operation under damaged-state will increase the possibility of accident.Therefore,the health monitoring and damage identification work of the bridge is of great significance to ensure the normal operation of the structure and avoid the occurrence of accidents.The Extended Kalman Filter(EKF)is a recursive updating algorithm for nonlinear systems,which is suitable for time-varying systems.Meanwhile the vehicle bridge interaction system is a time-varying system.EKF algorithm can apply into bridge structure damage identification use vehicle-bridge interaction vibration signal.This paper uses the EKF algorithm to identify the bridge structure damage.The influence of the different road roughness levels on the recognition algorithm is analyzed and use numerical example to validate the algorithm.Specific research work includes:(1)The vehicle bridge coupled vibration model under the smooth pavement is established.The state vector of EKF is constructed by structural modal coordinates and damage factor.The response of the bridge is taken as a measurement signal and used to identify of the bridge damage.The numerical example results show that the algorithm can effectively suppress the influence of noise and can identify the damage accurately,and EKF algorithm has strong robustness.(2)On the basis of EKF damage identification of smooth road,we further study the damage identification of bridge structure considering road roughness.By comparing the equations of the vehicle bridge interaction system under two kinds of pavement conditions.The effect of the road roughness on the response of the bridge is treated as the noise processing,and a simplified algorithm for damage identification of the bridge structure based on EKF is proposed.Numerical example beam bridge shows that the simplified damage identification algorithm can achieve good damage identification results when pavement condition is good.(3)The simplified algorithm is more suitable for good road roughness condition.To improving the accuracy of damage identification algorithm when the road roughness is poor.Kalman filter is used to denoise the road roughness signal which contains noise,and then a bridge damage identification algorithm based on EKF algorithm is proposed.The numerical example shows that,the EKF damage identification method proposed in this paper can accurately identify the damage of bridge under different road roughness level and noise level,and the parameter analysis shows that the identification results are not sensitive to the change of vehicle speed,vehicle weight and other factors.