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Modal identification of structures using eulerian-phase based video motion magnification and analysis

Ismailov, Kadyrbek
Structural identification (St-Id) and dynamic analysis have been crucial in civil engineering structures, mainly buildings and bridges. In order to observe the vibrations of structures, networks of high-sensitivity sensors have been used. There are several limitations of such monitoring systems including cost, labor, number of sensors, and installation. A recent method called phase-based video magnification can be utilized in civil engineering to have a practical visual approach instead of array of sensors. This method will be useful especially for tall and long structures like skyscrapers and long span bridges where distance between sensors is a problem for data acquisition. Furthermore, video based modal testing is more convenient; number and spatial distribution of pixels is advantageous. Use of HD video as an input and magnification of tiny motions, which are not seen by naked eyes, are studied in this thesis. The phase-based video magnification algorithm is used and improved to obtain resonant mode shapes and frequencies of simple structures through video based spectral analysis. Simple ruler and cello wire vibrations and two pedestrian bridges were used as test structures to validate results directly obtained from video recordings.