Novel Approach for the Monitoring of Localized Pitting Corrosion in Steel Bars Through a Combined Use of Distributed Optical Fiber Sensors and Finite Element Analyses

This paper proposes a novel method to quantitatively monitor pitting corrosion level of steel bars through a combined use of distributed optical fiber sensing (DOFS) technique and mechanical analysis using finite element modeling (FEM). Tensile tests on steel bars with notches simulating corrosion pits were conducted, and strain distributions measured from fiber sensors attached on tensile bars were analyzed. Further, three-dimensional FEM demonstrated that the monitored strain distribution along a line on the bar surface was greatly dependent on its position relative to the pit mouth. Finally, the procedure to determine the corrosion level from DOFS data and FEM results was presented by mathematically comparing the similarity of strain curves given by the fiber sensor on a corroded bar and FEM of steel bars with different corrosion levels. This study revealed the importance of considering the relative location of fiber sensors when explaining the data of DOFS, and also provided a promising way to quantitively monitor the pitting corrosion level based on the strain distribution of steel bars.