Local Strand-Breakage Detection in Multi-Strand Anchorage System Using an Impedance-Based Stress Monitoring Method—Feasibility Study

Abstract

This study investigates the feasibility of impedance-based stress monitoring method for local-strand breakage detection in multi-strand anchorage systems. Firstly, stress fields of a multi-strand anchorage system are numerically analyzed to examine anchorage’s responses sensitive to local strand breakage. Secondly, an impedance-based stress monitoring technique via the PZT interface is outlined. Thirdly, a novel hoop-type PZT interface is designed for the multi-strands anchorage to monitor the stress variation induced by the strand breakage. Local dynamic responses of the hoop-type PZT interface are analyzed to predetermine the effective frequency ranges. Finally, the numerical feasibility of the proposed method is verified on a seven-strand anchorage system under various strand breakage cases. Variations in impedance responses are statistically quantified, and broken strands are localized by linear tomography analysis of damage indices. A lab-scale experiment is also conducted on a multi-strands anchorage to evaluate the realistic performance of the hoop PZT interface for impedance-based stress monitoring method.

Damage‐sensitive impedance sensor placement on multi‐strand anchorage based on local stress variation analysis

“…Tetrahedron elements were used to mesh the bearing plate, and the anchor head and hexahedron elements were used for the wedges. To simulate the remaining structure (i.e., supported streel frame), 3D‐spring contacts with the selected stiffness of k z = 5 × 10 15 N/m/m 2 and k x = k y = 0.5 k z were assigned at the bottom of the bearing plate, as detailed in Figure . To simplify the FE model, the contact between the wedge and the anchor head and the contact between the anchor head and the bearing plate were assumed as the perfect bonded contacts …”

“…So far, just a little effort has been made on the application of the impedance‐based method to full‐scale multi‐strand anchorage systems . On the basis of the piezoelectric interface technique, Dang et al proposed a hoop‐type interface equipped with multiple PZTs to detect damaged strands in a multi‐strand anchorage system. The idea is that the strand breakage will cause local stress variations over the anchorage and consequently modify the EMI responses of the PZTs on the hoop‐type interface.…”

Sensing Region Characteristics of Smart Piezoelectric Interface for Damage Monitoring in Plate-Like Structures

“…The FE modeling of piezoelectric effects of the PZT interface requires multiple coupled physics (i.e., electrical and mechanical), which act simultaneously during the excitation of the sensor. Due to its electrical-mechanical simulation capabilities which have been widely accepted by the academic society, COMSOL Multiphysics was selected to simulate the piezoelectric effects [7,26,27,28].…”

Negative Pressure Waves Based High Resolution Leakage Localization Method Using Piezoceramic Transducers and Multiple Temporal Convolutions

“…Another type of PZT application is based on electromechanical impedance (EMI) [46,47,48]. EMI is widely used for the health monitoring of various structures, for example, strength development monitoring of cementitious material [49], cable force monitoring in tendon-anchorage [50], bolt-joint structural health monitoring [51], impedance monitoring in tendon-anchorage [52], and local strand-breakage detection in multi-strand anchorage system [53]. Furthermore, the performance of EMI based SHM method can be improved by using multilevel wavelet decomposition [54], metamaterial plasmons [55], artificial neural networks [56] and fuzzy network [57], locally resonant piezoelectric metastructure [58] and so on.…”