3D-DIC Technique for Strain Measurement in FRP Strip Externally Bonded to Concrete Specimens

Three-dimensional digital image correlation (3D-DIC) is widely used in measuring the displacement and strain distribution due to its non-connected, high-accuracy and non-destructive property. In this paper, 3D-DIC method is used to study the bond performance between the bonded fiber-reinforced polymer (FRP) sheet and the concrete block during a single shear test. The strain distribution in FRP sheet during the whole loading process is obtained with DIC method. Based on the measured strain distribution, the local bond–slip behavior of FRP–concrete interface can be further analyzed. Therefore, the feasibility of the 3D-DIC system applied in experimental studies on the mechanical properties of civil engineering structures is proved.