Piezoelectric‐based hoop‐type interface for impedance monitoring of local strand breakage in prestressed multi‐strand anchorage

Summary In this study, a piezoelectric‐based interface technique for impedance measurement is presented to monitor local strand breakage in multi‐strand anchorage systems. Firstly, a hoop interface‐based impedance measurement model is designed based on stress behaviors of the multi‐strand anchorage. Coupled dynamic behaviors between the lead zirconate titanate (PZT) interface and the target tendon anchorage are interpreted to determine sensitive frequency ranges under local strand breakage. Next, a prototype of the PZT interface is designed to fit into the target multi‐strand anchorage to monitor the stress variations induced by local strand breakages. Dynamic characteristics of the PZT interface are numerically analyzed to sensitively catch impedance signals in predetermined frequency ranges. Finally, a series of damage scenarios are tested on a full‐scale multi‐strand anchorage system to evaluate the feasibility of the PZT interface for monitoring a series of strand‐breakage cases. Impedance responses of the PZT interface prototype are analyzed to determine damage‐sensitive frequency ranges. Linear tomography of root‐mean‐square‐deviation (RMSD) indices is utilized to localize damaged strands.