Comparison of Surface Bonded Piezoelectric Transducers and Concrete Vibrational Sensors in Damage Detection of Reinforced Concrete Beams

Reinforced concrete (RC) construction stands as one of the most prevalent engineering endeavors, underscoring the importance of routine structural health assessments. Numerous factors, including overloading, design deficiencies, and fatigue, pose risks to RC structures by inducing cracks in various components. These damages significantly compromise the strength of RC constructions, necessitating vigilant monitoring to avert catastrophic structural failures. Structural health monitoring (SHM) techniques primarily aim to detect such damages. Leveraging piezoelectric (PZT) principles, the electromechanical impedance (EMI) methodology emerges as a promising SHM approach. EMI relies on variations in responses recorded through the electromechanical interaction between PZT and the structure to identify structural damages. Admittance signatures, comprising conductance (G) and susceptance (B), serve as indicators of structural condition, with deviations in the plot of G across a frequency range signaling structural deterioration. PZT transducers, either embedded within the structure or surface bonded, facilitate damage monitoring. This study aims to assess the damage detection capabilities of surface bonded PZT and embedded concrete vibrational sensors (CVS) in grade M25 RC beams. The root mean square deviation (RMSD) serves as the damage index, derived from variations in signatures recorded at different load levels. Experimental testing, conducted on nine RC beam specimens using a universal testing machine (UTM), yielded reliable results for comparison. Comparative analysis between surface bonded PZT and embedded CVS evaluated their performance in detecting structural anomalies under various load levels using RMSD values. Baseline conductance signatures revealed a lower amplitude for CVS due to inherent damping effects within the concrete material. Additionally, CVS consistently displayed lower RMSD values than PZT across different load levels, indicating lesser sensitivity to surface cracks and defects owing to its embedded position within the concrete.