The application of the digital image correlation in the three-point bending test of concrete prisms

The digital image correlation (DIC) technique is increasingly used, especially for monitoring strain distribution and deflection of concrete structure elements. This technique is an alternative to measuring deflections and strains. In this research, four concrete prisms were tested to evaluate the accuracy of the DIC technique. Two concrete prisms, with dimensions of 310 mm x 150 mm x 150 mm, and the others with 510 mm x 150 mm x 150 mm, were used as specimens. The specimens were prepared with a white base coat and speckles to facilitate image tracking. A hydraulic actuator was used to load the specimen during the test, while a high-resolution camera captured video footage of the test. The collected video data was processed into sequential images using Ncorr V-1.2, integrated with MATLAB, to obtain deflection and strain distribution. The application of the DIC method in this study generates the normal strain in the x and y directions and shear strain xy, major and minor principal strains, as well as displacement values. The DIC results are compared with the displacement value results obtained from conventional tools (LVDT). The results show that the DIC technique accurately measures displacements and strains in concrete prisms.