Using Digital Image Correlation (DIC) to Monitor the Behavior of Masonry Walls

Monitoring specimen deformation is an essential aspect of structural testing. Strains and displacements are typically measured via electronic sensors (e.g., LVDTs and strain gauges). However, all of these sensors measure discrete spatial values. Moreover, placing instruments in contact with specimens poses a high risk of instrument damage in the event of sudden or explosive failures. Digital Image Correlation (DIC), which determines specimen displacements from a set of consecutive specimen images, overcomes both these shortcomings. Accurate DIC displacements depend on surface preparation and camera recording parameters, which require careful consideration in the context of a structural test. However, if these parameters are appropriately considered, for large-scale specimen testing it may be possible to obtain high-quality data with minimal risk and relatively low cost. In this study, the cost-effective use of DIC in the context of the testing of large-scale masonry walls (2 m in height) was examined. Readily available commercial recording cameras (iPhone 13, Go Pro Hero 11) were used to record videos of a prepared specimen in an experimental test and compared against readings from calibrated LVDTs. The results of DIC showed good agreement with LVDT readings. DIC was also found to permit the capture of "secondary" sets of data not typically measured in a routine experiment. These data pertain to explosive failure modes and experimental boundary conditions. The capture of secondary data can inform the interpretation of experimental results.