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Research On The Vibration Of Cable-stayed Bridge Based On Video Image Edge Detection Technology

Posted on:2019-09-03Degree:MasterType:Thesis
Country:ChinaCandidate:M J XuFull Text:PDF
GTID:2382330548473780Subject:Bridge and tunnel project
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Structural vibration testing and modal parameter identification are basic methods for studying structural dynamic characteristics.They play a very important role in health monitoring and safety assessment of bridge structures.The traditional vibration test belongs to non-contact measurement,in order to fully grasp its vibration characteristics,in many parts of the layout of the sensor structure,site preparation work is tedious,the scene has poor anti-interference ability,low density,test the test takes a long time,so the development of a non-contact,convenient operation,anti-interference ability strong surface,full scale advantages,and can realize automatic recording,processing and real-time measurement of continuous data is a very necessary work.Based on the experimental model of cable-stayed bridge,the cable-stayed bridge vibration video and cable were collected,then the vibration video decomposition method for digital image frame sequence,using orthogonal polynomial fitting sub-pixel edge detection of each image,obtain the edge points.Each time a cable-stayed bridge by Matlab the program reads the whole vibration of the cable-stayed bridge edge data can be obtained,the vibration time history of cable-stayed bridge,and then the measured data were obtained through modal analysis of DASP system,the cable-stayed bridge vibration frequency and vibration type.This method is discussed theoretically and experimentally.In this paper,the modal data of the laboratory cable-stayed cable model are detected by the image edge detection technology mentioned above.In view of the nature of the real bridge detection,some adjustments are made to the technology.By collecting the vibration video ofthe cable of a real bridge,the first four frequency of the cable is detected,and compared with the data obtained from the dynamic tester,the error is within a reasonable range,which can meet the engineering detection application.In this paper,the engineering application of image edge detection technology is discussed and verified experimentally.The main work and research results of this paper are as follows:(1)the research background and significance of video image edge detection technology and the research status and development trend at home and abroad are described.The process of digital image acquisition in the video image edge detection technology is introduced from the angle of optical imaging.The mathematical principle of the digital image edge detection method is described.The shortcomings of traditional bridge structure vibration detection methods are discussed.The video and image measurement technology is summarized and analyzed.Compared with the traditional detection technology,the advantages of video image edge detection technology applied to structural vibration detection are demonstrated.(2)using Midas finite element software to simulate and calculate the cable-stayed bridge model structure,get the first three natural frequencies and mode shapes of the main girder of the cable-stayed bridge,and get the first four natural frequencies and mode shapes of the cable through the same model.(3)the vibration process using appropriate video format of the cable-stayed bridge,including the implementation of the program of video decomposition,image preprocessing,edge edge calculation,time domain signal read four module by using Matlab software,DASP system to complete the analysis of measured signal based on identification of the cable-stayed bridge model the natural frequency and vibration mode.Compared with the results of Midas finite element software,the reliability and accuracy of structural vibration modal parameter identification based on video image edge detection technology are demonstrated.(4)in the process of collecting the main girder vibration of cable-stayed bridge,a time synchronization identification method based on the peak value of sound is put forward to solve the time synchronization problem of multi position edge stitching.Under the condition of convenience and accuracy,the 3D vibration of the main girder of cable-stayed bridge is identified by multi position and multi angle,which shows the superiority of the video detection technology.(5)demonstrate the feasibility of video and image detection technology to identify the vibration modal parameters of cable-stayed bridge model,and accurately calculate the cable force of cable.In this paper,we try to move towards the application area.We do the video image edge detection on the single point of the real bridge and detect the first four frequencyof the cable.Compared with the data obtained from the dynamic tester,the error is within a reasonable range,which can meet the engineering detection application.The feasibility of the video image edge detection technology in engineering is demonstrated.
Keywords/Search Tags:modal parameter identification, video image, edge detection, polynomial fitting, three-dimensional vibration, real bridge detection
PDF Full Text Request
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