Non-uniform Field of Concrete Deformations of Circular Cross-Section Columns Under Cross Bending Applying Digital Image Correlation Method

The paper covers experimental techniques for investigating non-uniform field of concrete deformations by means of applying digital image correlation method. With the help of this method, the process of initiation, formation and development of a diagonal crack has been investigated up to the point of oblique section failure and qualitative assessment of deformations in the compressive zone and the tensile zone of concrete has been performed. Non-contacting method of digital image correlation is well positioned to determine the field of deformations, it requires minimum equipment and is simple and accurate enough—up to 0.004% of absolute deviation at determining deformations, it makes it possible to analyze transient processes under deterioration with the help of a high-speed camera. Deformations obtained by means of digital image correlation method corresponded to the deformations determined by instruments, and the pattern of deterioration closely corresponded to the actual deterioration pattern. The use of digital image correlation method for conducting experimental research makes it possible to monitor the process of the initiation, formation and development of a diagonal crack up to the moment of deterioration along the oblique section, perform quality assessment of the deformations in the compressive and the tensile zone of concrete, in longitudinal reinforcement bars in the section with a crack at any stage of deformation.