Abstract
The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD) have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz) range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S) will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures.
Highlights
With the reported increasing number of collapses occurring in major infrastructures, health monitoring of civil structures has become of significant importance
It is observed that the damage close to the piezoelectric lead zirconate titanate (PZT) changes the root mean square deviation (RMSD)-S of the high frequency range significantly, whereas the damage far away from the PZT
PZT transducers have been used for monitoring of structures based on two principles: (1) using multiple PZTs in the wave propagation technique, and (2) using a single PZT transducer in the electromechanical impedance (EMI)
Summary
With the reported increasing number of collapses occurring in major infrastructures, health monitoring of civil structures has become of significant importance. The main drawback of these techniques is that they rely on a small number of low order modes, which, being global in character, are not very sensitive to the presence of localized damages Another limitation of these techniques is interference from ambient vibration noise, which happens to be in the low frequency range, typically less than 100 Hz [2]. Larger difference between the baseline signature and the subsequent signatures would result in bigger RMSD values The principle behind this technique is to apply high-frequency structural excitations (typically higher than 30 kHz) through surface-bonded PZT transducers, and measure the impedance of structures. The PZT admittance signatures in a frequency range of 30 to 400 kHz for various structural damages have been recorded and the RMSD-S values are calculated. A damage identification scheme is proposed to estimate the location and severity of damage in concrete structures
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