Standard Article

Multiwire Strands

Other Applications

  1. Francesco Lanza di Scalea1,
  2. Ivan Bartoli1,
  3. Piervincenzo Rizzo2,
  4. Alessandro Marzani3,
  5. Elisa Sorrivi3,
  6. Erasmo Viola3

Published Online: 15 SEP 2009

DOI: 10.1002/9780470061626.shm119

Encyclopedia of Structural Health Monitoring

Encyclopedia of Structural Health Monitoring

How to Cite

di Scalea, F. L., Bartoli, I., Rizzo, P., Marzani, A., Sorrivi, E. and Viola, E. 2009. Multiwire Strands. Encyclopedia of Structural Health Monitoring. .

Author Information

  1. 1

    University of California, Department of Structural Engineering, San Diego, CA, USA

  2. 2

    University of Pittsburgh, Department of Civil and Environmental Engineering, Pittsburgh, PA, USA

  3. 3

    University of Bologna, DISTART, Bologna, Italy

Publication History

  1. Published Online: 15 SEP 2009


Multiwire strands are used in civil structures as prestressing members of posttensioned concrete systems, and tendons of cable-stayed and suspension bridges. This article discusses the use of ultrasonic guided waves for providing both defect detection and stress monitoring capabilities in the common seven-wire, 15.34-mm (0.6-in.) steel strands using embedded transducers. The semianalytical finite element method is first used to model the multimode and dispersive vibrational behavior of the strand waveguide. Experimentally, magnetostrictive transducers probing the strand as a whole are shown to be sensitive to small notch-like defects in reflection-based measurements, which are aided by robust feature extraction and statistical defect classification. Small piezoelectric transducers probing the individual wires comprising the strand are, instead, shown to be suitable to monitor the level of stress applied to the strand. In particular, the ultrasonic transmission between the peripheral wire and the central wire, quantified in terms of ultrasonic energy and frequency, is found to be highly sensitive to the level of stress. The method discussed is currently under laboratory development, and its effectiveness in the field remains to be demonstrated.


  • prestressing strands;
  • ultrasonic guided waves;
  • feature extraction;
  • semianalytical finite element method