Enhancing the Identification of Stiffness Changes in Cables with Wave Propagation Features: Illustration with Laboratory and Field Tests

Abstract

Vibration-based techniques are relevant in assessing the integrity of cables in bridges and other civil engineering structures, as they permit the simultaneous identification of stiffness properties and the installed axial force. However, the accuracy of the inverse problem largely depends on the proper characterisation of the restraints at the supports and the free vibration length. Moreover, the axial force may not be considerably modified in the presence of small, localised damage. In such a context, the ViBest research group has been developing an alternative approach based on the frequency-dependent velocities at which transverse waves propagate along a cable member. These quantities are independent of boundary conditions and can be characterised along broad frequency ranges, thus enhancing their damage sensitivity. In this study, results from laboratory and field tests demonstrate that wave velocities can be used to quantify stiffness variations along a damaged cable or differences between members with the same cross-section that would be imperceptible using only modal features.