Application of 2-dimensional digital image correlation for mapping bond strain and stress distribution in concrete

Abstract

Buildings and civil engineering structures nowadays are mostly constructed using reinforced concrete. In the reinforced concrete, one of the fundamental factors that influence its strength is bond between bars and concrete. In the reinforced concrete, one of the fundamental factors that influence its strength is bond between reinforcement bars and concrete. A lot of research on concrete anchorage bond had been carried out since 1913. However, till today the exact behaviour of anchorage bond in reinforced concrete is not very clear. An attempt to trace the stress contour in concrete due to the presence of anchorage bond had been made. Two dimensional digital image correlations were applied to images of pull-out concrete test blocks. Full-field strains contour on the surface of the concrete blocks were obtained at various level of pull-out forces using digital image correlation software. The strains were converted to stresses using plane stress concrete material constitutive equation. The results of this study show that the digital image correlation method is able to trace the stress components in the concrete surface under the influence of anchorage stresses. The distribution of the longitudinal stresses in the concrete surface along the reinforcement length was found to be nonlinear with maximum value occurs near the loading end.