The behavior mapping of masonry arches subjected to lumped deformations

This work presents the proof-of-concept for a fast and cheap non-destructive monitoring system called “Behavior Mapping BP” for the analysis up to collapse of masonry. It belongs to a vision-based measurement similar to DIC but much more straightforward and inexpensive. It identifies and quantifies mechanical deformations between rigid blocks solely through a 4x4 point grid and works by extracting data from videos. First, the possible motions between two rigid blocks are described and followed by how the point grids can identify and quantify their motions through repeated calculations of lengths, dot products, and right triangles. Two benchmark tests were performed to validate the approach. The first was through images of defined deformations and the second was video recordings of an in-scale arch subjected to horizontal springing settlement. 2D homography provided the key to transform the recorded point grids to the cartesian plane for measurement. Finally, the procedure is successfully applied to a case study of a video recorded failure of a 27-block arch: with only the knowledge of the point grid template and extracting images from the video, the mechanical joints motions are identified and quantified. The procedure can be easily applied to any masonry wall in-plane loaded and -using more than one camera- to out-of-plane loaded panels.