Automated modal identification in operational conditions using 3D stabilization diagrams

The development of efficient vibration-based Structural Health Monitoring (SHM) methodologies capable to timely detecting the onset of anomalies and possible damage in structures is still a challenging task, especially for large infrastructures, complex constructions and historic buildings. SHM strategies are often based on the automated extraction of the modal parameters from the signals collected during normal (operational) conditions and different approaches have been proposed in the literature for the automation of Operational Modal Analysis (OMA). Within this context, the paper focuses on the development of a new automated OMA procedure, which involves the construction and the automated interpretation of tridimensional stabilization diagrams, avoiding the initial tuning of the input parameters characterizing the SSI techniques and resulting in modal estimates with improved accuracy. The algorithm is exemplified through its application to data collected by continuous dynamic monitoring of two different bridges.