Numerical and experimental studies on damage detection of a concrete beam based on PZT admittances and correlation coefficient

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The electromechanical impedance (EMI) technique has been shown promising for structural health monitoring, in which the PZT patch performs both functions of sensor and actuator simultaneously. The main merits of EMI technique for damage detection are its high frequency actuation feature and non-model based, so it can detect the occurrence of structural damage and is sensitive to small damage. However, its deficiency is difficult to determine the location and severity of damage. In this paper, a new damage detection method is proposed based on electromechanical admittances (inverse of impedance) of multiple PZT patches and a damage index, namely, cross-correlation coefficient (CC). Numerical and experimental studies on damage detection of a plain concrete beam based on the proposed method have also been reported. In the studies, three PZT patches were bonded to the surface of a plain concrete beam with certain intervals. By measuring the electromechanical admittance signals of each PZT in different frequency ranges, the occurrences of several crack damage of a plain concrete beam were monitored; by integrating with CC index, the damage locations and severities of the plain concrete beam were also determined. It is also found that the numerical and experimental results were also compared. It can be concluded that the proposed damage detection method was quite effective and sensitive to concrete.