Architecture and Civil Engineering

Structural health monitoring (SHM) assists engineers in maintaining structures, making them safer and more cost effective. Digital image correlation (DIC) techniques applied to SHM are non-contact, fast, and accurate techniques that are easy to apply. This investigation determined the minimum resolution of the state-of-the-art, OpenSource DIC – based tool “Improved DIC”. Initially undetected damage at low strains in connections of a real-world bridge motivated this investigation, whose detection would have restricted its spread, leading to lower repair costs. A cantilevered plate specimen was transversely loaded in the laboratory, and the longitudinal strain was measured at six different locations, using the OpenSource DIC-based tool. The DIC strains were compared against those measured by traditional strain gauges. Strains as low as 0.015% were measured accurately using the OpenSource tool. Additionally, this study demonstrated that small out-of-plane specimen movements that inadvertently occurred even in controlled laboratory conditions led to noise in the DIC-based strain measurements. Hence, it was also concluded that prior to implementing this technique in a real structure to detect small strains, it is desirable to determine the limits of out-of-plane specimen displacement within which it is practical to use this technique to measure strain.