Structural damage detection using digital video imaging technique and wavelet transformation

Damage in structures may render risk of catastrophic failure. Identifying damages and their locations is termed as damage detection. In this paper, use of digital video imaging is proposed for detecting damage in structures. The theory of measuring structural vibration using high-resolution images is presented first, based on sub-pixel edge identification. Then a concept of mode shape difference function is developed for structural damage detection. A laboratory test program was carried out to implement these concepts using a high-speed digital video camera. The images were analyzed to obtain displacement time series at sub-pixel resolution. Mode shapes were obtained from the time series to find the mode shape difference functions between the damaged and the reference states. They were subjected to wavelet transformation for determining the damage locations. Results show that the proposed approach is able to identify the introduced damage cases and their locations.