Image-based operational modal analysis and damage detection validated in an instrumented small-scale steel frame structure

The use of image-based techniques in structural dynamics is constantly growing thanks to the decrease in the cost of high-speed cameras and the improvement in image processing algorithms. Compared to traditional sensors, such as accelerometers or velocimeters, the use of fast cameras for data acquisition allows the number of measurements points to be significantly increased. However, such an abundance of points, not always lead to an increased accuracy of damage detection algorithms. With this in mind, we compare different damage detection techniques by using displacement data and modal quantities. A small scale steel frame structure is used to validate the damage detection by using measurements acquired through a high-speed camera with different image processing techniques. The Hybrid Lagrangian Particle Tracking (HLPT) algorithm and Digital Image Correlation (DIC) are both used to extract displacement measurements from images. The results are compared with those obtained with seismic class accelerometers which are normally used in the lab for such an application. Damage localization and intensity have been determined through image-based measurements without losing the accuracy obtained with accelerometers.