Ferrer, Belén, Acevedo Noda, Pablo, Espinosa, Julián, Mas, David
Targetless image-based method for measuring displacements and strains on concrete surfaces with a consumer camera
Construction and Building Materials. 2015, 75: 213-219. doi:10.1016/j.conbuildmat.2014.11.019
URI: http://hdl.handle.net/10045/53341
DOI: 10.1016/j.conbuildmat.2014.11.019
ISSN: 0950-0618 (Print)
Abstract: 
Measurement of concrete strain through non-invasive methods is of great importance in civil engineering and structural analysis. Traditional methods use laser speckle and high quality cameras that may result too expensive for many applications. Here we present a method for measuring concrete deformations with a standard reflex camera and image processing for tracking objects in the concretes surface. Two different approaches are presented here. In the first one, on-purpose objects are drawn on the surface, while on the second one we track small defects on the surface due to air bubbles in the hardening process. The method has been tested on a concrete sample under several loading/unloading cycles. A stop-motion sequence of the process has been captured and analyzed. Results have been successfully compared with the values given by a strain gauge. Accuracy of our methods in tracking objects is below 8 μm, in the order of more expensive commercial devices.
Keywords:Concrete, Strain measurement, Non contact measurement, Image processing, Stop motion, Targetless method, Centroid calculation
Elsevier
info:eu-repo/semantics/article