Uniaxial and lateral strain behavior of ribbed reinforcement bars inspected with digital image correlation

Knowledge about the plastic behavior of reinforcement steel bars in reinforced concrete (RC) structures is important, especially for seismic design. This paper presents the results of experimental tests where the main aim was to map the plastic deformations of long ribbed reinforcement bars, both in the axial and lateral directions, in order to provide useful information about the behavior of reinforcement bars inside concrete. The study showed that the digital image correlation (DIC) technique is very suitable for this kind of tests. The uniaxial stress-strain curves for side-by-side and different gauge lengths (1d, 3d, 5d, 10d) were identical all the way to the max stress, but after that the segment including the neck dominated the strain development. The Poisson's ratio increased rapidly during the yielding phase to 0.44-0.49 and was constant all the way to rupture. The location of the neck could be predicted at the end of the yielding phase.