Preliminary Study of Corrosion Damage Detection Using Natural Frequency Technique for Reinforcing Steel

This study presents a preliminary investigation into the correlation between corrosion-induced damage and changes in the natural frequency of reinforcing steel using a vibration-based monitoring (VBM) technique. Corrosion alters the mechanical and geometric properties of steel, reducing its cross-sectional area and stiffness, thereby leading to observable shifts in vibration characteristics such as natural frequency and mode shapes. To validate this phenomenon, the study employed a combined analytical, experimental, and numerical approach. Analytical modeling was performed using Euler-Bernoulli beam theory to establish baseline frequencies, while tensile testing was conducted to evaluate the mechanical performance of damaged steel specimens. Finite Element Method (FEM) simulations using COMSOL Multiphysics were used to analyze changes in natural frequencies across varying corrosion depths. The results showed a consistent reduction in natural frequency with increasing corrosion severity, particularly in vibrational modes located at the damage site. The comparison among analytical, experimental, and FEM data demonstrated strong agreement, with a maximum error of 0.545% in frequency prediction. These findings confirm the sensitivity of dynamic parameters to localized corrosion and support the feasibility of VBM as an effective non-destructive tool for early detection of structural degradation. The study contributes to the development of smart SHM systems aimed at improving infrastructure resilience and reducing long-term maintenance costs.