A novel vibration-based approach for damage identification and classification in FRP-retrofitted reinforced concrete beams under different loading stages
Manh Hung Tran, Duc-Duy Ho, Van-Sy Bach, Tran-Huu-Tin Luu, Chi-Khai Nguyen, Hong-Huan Chiem, Khanh-Hoang Vu
Abstract
Structural health monitoring (SHM) is indispensable in extending structural integrity because it detects early damage and enables timely maintenance. Recently, SHM has faced challenges such as applying to complex structures and classifying damage when multiple types occur simultaneously. This paper focuses on identifying and classifying damages in reinforced concrete (RC) beams retrofitted with fiber reinforced polymer (FRP) sheets. Initially, the vibration responses of an FRP-retrofitted RC beam are obtained through numerical simulation. The reliability of the simulation is verified by the experimental data. Subsequently, the modal strain energy (MSE) method is utilized to identify the locations of the damage zones within the beam. A set of indicators is introduced to assess the precision of the damage localization results. The damage progression in the beam is analyzed at different vertical load levels, reflecting the actual performance of the beam. The findings indicate that the MSE method provides a high degree of accuracy in detecting and locating the damages in the FRP-retrofitted RC beams. Especially, when minor damages appear, the proposed method performs effectively even with only the first mode data. Additionally, a novel approach is introduced to distinguish between the concrete’s cracking and the FRP’s debonding in the beam.