Automated Transmissibility‐Based Damage Detection for Output‐Only Systems

In this study, an automated transmissibility‐based procedure for damage detection is developed for output‐only systems. The application of transmissibility has been previously investigated for damage detection. Despite the advancements, current techniques are not applicable in a general way, as vast experience or expert knowledge is needed to achieve accurate results, particularly for the frequency range selection. Moreover, the extent of noise influence still needs to be adequately addressed. A novel procedure has been developed to resolve these issues. First, the frequency range is determined by applying modal coherence using the first singular value of the cross‐power spectral density (CPSD). Then, the transmissibility functions are calculated from the CPSD and smoothed using a moving mean approach to reduce the influence of noise. Afterward, the threshold is obtained from the transmissibility damage indicator values of the system’s healthy state. Finally, damage detection can be performed continuously for each subsequent dataset. The procedure is compared to damage detection based on eigenfrequencies and mode shapes using simulated data, demonstrating higher sensitivity to minor damages at low noise levels. Furthermore, the procedure is validated on experimental data from a steel cantilever beam, where various noise scenarios, damage severities, and damage positions are considered, and on field data from a lattice tower, showing high damage detection accuracy across three damage scenarios. The proposed procedure can be automated, demonstrating sensitivity to minor damages when high signal‐to‐noise ratio is available.