Bridge Dynamic Deformation Monitoring And Analysis Based On GNSS And Accelerometer

Deformation monitoring plays a vital role in Structural health monitoring of bridges,and is of great significance for the safe operation of bridges.GNSS monitoring technology has the advantages of all-weather,real-time,no intervisibility,automatic monitoring,and has been widely used in long-span suspension bridge,cable-stayed bridges and other flexible bridges.In the actual monitoring engineering of bridges,the complex monitoring environment such as the obstruction of buildings around the measuring station and the interference of vehicles on the bridge deck may lead to a low fixed ambiguity rate in GNSS calculation.In addition,the real-time positioning accuracy of GNSS monitoring technology has certain limitations.High sampling rate GNSS calculation results have significant measurement noise,making it difficult to monitor high-frequency components with smaller amplitudes in displacement information.Accelerometer sensors are easy to monitor high-frequency displacement signals of structures,but it is difficult to reconstruct low-frequency quasi-static deformation.This article studies the dynamic deformation of bridges based on two types of sensors,GNSS and accelerometer.The research focuses on three aspects:GNSS dynamic relative positioning quality control in complex monitoring environments of bridges,real-time reconstruction displacement of accelerometers under bridge vibration excitation loads,and adaptive fusion of GNSS and accelerometers.The main research content and conclusions of the paper are as follows:(1)In view of the shortcomings of the traditional GNSS dynamic relative positioning quality control method in the data preprocessing stage and the robust Kalman filter stage under the complex bridge monitoring environment,an improved Dynamic positioning combined quality control method is proposed from three aspects of data preprocessing,filter solution,and partial ambiguity fixation.The method is verified through static occlusion experiments and bridge site monitoring experiments,The results show that this scheme significantly improves the ambiguity fixation rate in GNSS solution compared to traditional schemes.(2)In view of the poor real-time performance of existing acceleration reconstruction displacement methods,a robust acceleration real-time reconstruction dynamic displacement method based on time-frequency fusion filtering is proposed.This method is compared with the traditional frequency domain integration method and the Tikhonov regularization reconstruction displacement method based on mobile windowing.The verification test is carried out through multiple sets of simulation experiments,shaking table experiments,and bridge site monitoring experiments,results indicate that the method proposed in this article has smaller time lag and better accuracy in monitoring displacement while ensuring real-time algorithm calculation,and can effectively reconstruct dynamic displacement information under bridge vibration loads.(3)Aiming at the problems that the existing integration methods of GNSS and accelerometer are difficult to process in real time and apply to the Deformation monitoring of medium and small span bridges,an adaptive fusion method of GNSS and accelerometer based on the dynamic deformation characteristics of bridges is proposed.This method is applicable to bridges with different dynamic deformation characteristics,and can give full play to the monitoring advantages of the two sensors.Two sets of bridge monitoring experimental data are tested,and the results show that the fusion method improves the accuracy of Deformation monitoring and can obtain the displacement information of the bridge structure in a wider frequency band.