Assessment of Stress-Strain Behavior of Corroded Steel Reinforcement Using Digital Image Correlation (DIC)

摘要

Understanding the stress-strain behavior of corroded rebars is essential for understanding the structural behavior of corroding reinforced concrete structures. However, conventional methods of testing have several drawbacks, which have led to differences in opinion among researchers regarding the mechanical behavior of corroded rebars. This article proposes an improved method using Digital Image Correlation (DIC) to assess the stress-strain behavior of corroded rebars. The study is conducted in two phases: (a) development of the testing and evaluation method and (b) determination of the mechanical properties (i.e., yield strength, ultimate strength, and ultimate strain) of naturally corroded cold-twisted deformed (CTD) steel rebars using the developed method. The stress-strain behavior of one pristine plain mild (PM) steel and 13 naturally corroded steel rebars collected from a 15-year-old building are investigated in this study. The experimental results show that the proposed method can provide more accurate estimates of mechanical properties than the conventional methods. The developed method facilitates a better understanding of the stress-strain behavior at the fracture location (FL) and other local points of interest on corroded steel rebars. Because DIC measures local strains, the proposed method is able to measure local strain heterogeneity and therefore distinguish between the effects of geometrical variations from those due to true material degradation. This is in contrast to the conventional methods wherein deformation is measured over a finite gauge length, which results in a measurement of average deformation rather than true local deformation. This study emphasizes the need for measurement of full-field deformation to assess the stress-strain behavior of the corroded rebars with highly uneven cross-sectional area.