Crack detection in a concrete beam using two different camera techniques

The study presents an application of two different optical measurement techniques for the detection of cracks at the surface of a realistically sized concrete beam subjected to flexural loading conditions. Both techniques provide displacement measurements in a discrete number of points on the surface. Based on these displacement fields, deformations are calculated by means of the Green-Lagrange strain expression. The study deals with the relationship between cracks and the concept of deformation and it examines which of the two methods presented appears to be the most suitable for crack prediction or detection. The study shows that it is possible to detect the appearance and evolution of cracks, even before the cracks become visually detectable, with both methods and reveals their complementarities.