Degradation phenomena due to aging, severe environment or fatigue, and damage induced by hazardous events, such as earthquakes, fire, or explosions, may affect the performance and safety of civil structures. Visual inspections, typically in combination with destructive and nondestructive investigations on selected portions of the structure, and scheduled maintenance are the conventional approaches to damage detection and management. However, the local nature of tests, the subjectivity of the expert judgment, and the costs and very limited frequency of inspections have solicited strong research efforts, over the last decades, to change the paradigm, leading to the development of innovative structural health monitoring strategies relying on the analysis of the global, continuously measured, response of the structure. As a result, maintenance programs are more and more going to be based on the effective structural health conditions, as assessed by monitoring, rather than on a periodic basis.

Different approaches have been developed for damage detection based on the incoming data. Modal based damage detection is probably one of the most popular approaches to SHM of civil structures, exploiting the development of several robust automated Operational Modal Analysis (OMA) algorithms in the last decade. It is based on the assumption that damage affects the stiffness properties of the structure and, as a consequence, its modal properties. In spite of the significant advantages and proved effectiveness of the technique, limitations to its extensive application come from the reliability of automated OMA and the sensitivity of the estimated modal parameters to environmental and operational variables (EOVs), which can affect the reliability of damage detection. Furthermore, the extension of these techniques to also address the tasks of damage localization and quantification is yet to be achieved and related research is still at the development stage.

The scope of the special issue is to publish original research papers in the field of automated OMA for modal based SHM. The special issue will mainly focus on the development of new methods of automated OMA and its applications to damage identification, that is, detection, localization, and quantification. Theoretical studies and numerical simulations as well as practical applications are welcome. Papers concerning special applications of automated OMA and postprocessing of results will be also considered.

Potential topics include but are not limited to the following:

• New methods of automated Operational Modal Analysis
• Performance assessment of automated Operational Modal Analysis methods
• Applications of automated Operational Modal Analysis for modal parameter tracking and structural health monitoring
• Postprocessing of results of automated Operational Modal Analysis: compensation of environmental factors, damage detection, localization, and quantification
• Automated Operational Modal Analysis of structures exposed to natural or man-made hazards (e.g. earthquakes, floods, landslides, fire, and explosions)
• Special applications of automated Operational Modal Analysis (e.g. materials characterization, tensile load estimation, and structural identification)