Application of three-dimensional digital image correlation to the core-drilling method

We present a non-destructive technique for the determination of in situ stresses in concrete structures, referred to as the core-drilling method. The method is similar to the American Society for Testing and Materials (ASTM) hole-drilling strain gage method, except that the core-drilling method is formulated in terms of displacement rather than strain. Measurements in the current work are performed with traditional photogrammetry, and the more novel (and more accurate) three-dimensional digital image correlation. In this paper we review the background elasticity theory and we discuss the results of verification experiments on steel plates. Calculated normal stresses are within 17% of applied values for photogrammetry, and 7% for three-dimensional digital image correlation.