Study On The Vibration Testing Of Continuous Beam By Digital Image Processing Technique

The Vibration testing and modal parameter identification occupy a very importantposition in the detection and evaluation of bridge structure.The thesis refers to the existingcomputer image processing technique, aims at digital image measuring techniques, carrysout theoretical research and laboratorial dynamic response model test of bridge structures.The thesis makes more comprehensive discussion of the research background, theoreticalsignificance, existing achievements and the current problems of dynamic parameteridentification methods and digital image measuring techniques, author focus on identifyingthe dynamic parameters by digital image edge detection method,demonstrate the feasibilityof the method by laboratorial model test.The main research works innovations of this paper are as follows:Firstly, the thesis summarizes the disadvantage of existing bridge structure vibrationdetection method, analyzes the main methods in image measuring techniques which areimage edge detection method and digital image correlation method,gain some advantages ofstructural vibration test using image measuring techniques.Secondly, the author apply ordinary digital camera and PC as its hardware,implementvideo acquisition and analyze, image preprocess, image process, signal analysis in MATLABenvironment. The author identify natural frequency, damping ratio and mode of continuousbeam by test,compare with DASP system modal parameter identification results and FEMresults by MIDAS, demonstrate the reliability and accuracy of modal parameteridentification by digital image measuring techniques.Thirdly, the author make use of digital image measuring techniques to identify twosections mode shapes of the same continuous beam model,fitting complete shapes ofcontinuous beam with calibrated scale factor.