Identification of interfacial debonding in reinforced concrete structures with active piezoelectric sensing networks

A distributed active sensing network of piezoelectric transducers side-mounted onto the rebar is developed for detecting, localizing, and quantifying interfacial debonding in reinforced concrete (RC) beams. A sequential scanning method is utilized to track the potential interfacial debonding by exciting the longitudinal guided waves in one set of transducers and recording the signals from other transducers. Three potential damage scenarios, which are considered within two types of sensor excitation-reception schemes, are addressed in the proposed debonding identification method. Individual guided wave propagation models considering the mode conversion and contact acoustic nonlinearity are constructed for localization and quantification of interfacial debonding under the three considered damage scenarios. To substantiate the advancement of the proposed piezoelectric sensing network, the signal actuating and sensing efficiency between the proposed side-mounted transducer and conventional end-mounted transducer strategies are compared. The numerical and experimental outcomes from four varied actuating-sensing schemes corroborate the applicability and effectiveness of the proposed transducer side-mounting strategy. To verify the accuracy and feasibility of the active piezoelectric sensing networks in identifying interfacial debonding, a series of RC beams considering eight damage cases with diverse debonding locations and lengths are experimentally evaluated. The combined theoretical, numerical and experimental results testify that the proposed methodology is capable of accurately detecting, localizing, and quantifying the interfacial debonding in RC beams.