Study On Application Of Digital Image Processing Technique In The Vibration Testing Of Beam And Cable Structure

The vibration of bridge structure is an important factor influencing the operation and safetyof the bridge, therefore understanding the dynamic characteristics become very important.The thesis refers to the existing home and abroad researches about optical measurement andcomputer image processing technique, improving the image measuring method of dynamiccharacteristics of bridge structures, and carrying out lab model test. The thesis consulting agreat deal of publications and literature on structure identification methods of dynamicparameter and digital image measuring techniques, author makes more comprehensivediscussion of the research background, theoretical significance, existing achievements andthe current problems of structural dynamic parameter identification methods.The main research works innovations of this paper are as follows:Firstly, the thesis reviews and analyzes the main methods in image measuring techniquesand image edge detection, giving detail introduction on polynomial fitting method of imageedge detection.Secondly, the author introduces the testing process of video image vibration testtechnology. With ordinary digital camera and PC as its hardware, the vibration test of simplysupported beam is performed which identified natural frequency, damping ratio and mode.On the other hand, comparing with the result using DASP vibration testing method.Thirdly, the vibration test of cable model is carried out to identify the cable's naturalfrequency and second frequency, and furthermore to get the cable force using the method ofmeasuring the frequency. At last, the engineering application of cable force measurement isbrief introduced.