Determination of stress and displacement with the digital image correlation method

Stress and displacement are the two most important parameters in civil engineering laboratory applications. Mechanical-based measurement techniques are generally used to determine these parameters. With the advancement of technology every day, new measurement techniques are being developed as an alternative to existing measurement techniques. In this thesis, the use of digital image correlation (DIC) method, which is an optically based measurement technique, as an alternative to traditional measurement techniques in determining stress and displacement in civil engineering laboratory applications was investigated. For this purpose, measurements were made on a total of 19 samples, 14 beam samples in two different sizes and 5 wall samples. 7 of the beam samples were produced as reinforced concrete beams, while the other 7 were produced as unreinforced. Macro synthetic fiber (MSF) additives were used in various proportions (0%; 0.2%; 0.4%; 0.6%) in the concrete mixtures of the beams. The wall samples are plastered on one side or both sides and plastic composite reinforcement (geogrid) in plaster has been produced in various properties according to the usage situation. A three-point bending test was applied on the produced beams and a diagonal loading test on the walls, and the displacements in the samples were recorded with a conventional deformation meter (LVDT-Linear variable differential transformer) and a high resolution digital camera for measurement by DIC method. By comparing the findings obtained with LVDT and DIC measurements, the usability of the DIC method for the measurement of displacements in civil engineering laboratory applications was investigated. In addition, the stress changes occurring on the surface of the samples during the loading tests were visualized by DIC method. The development of cracks on the sample surfaces was analyzed visually. When the DIC and LVDT measurement results were evaluated, it was found that the displacement values obtained by both methods were in harmony with each other. It has been demonstrated that the DIC method can be used to visualize the stress changes occurring on the sample surfaces.