Operational Modal Analysis of civil engineering structures: aims and applications

Vibration-based monitoring and assessment techniques are gradually more and more used and becoming very attractive for civil engineering applications due to their powerful possibilities: in fact they allow to recognize the real dynamic behaviour of existing structures in their operative conditions, to control the level of vibrations, to develop suitable numerical models (useful for the design and assessment of retrofit works) and they can provide localization and quantification of structural damage. In the paper, the basic aims and some examples of operational modal analysis applied to civil structures will be exposed and discussed. In particular, it will be illustrated the analysis of several case studies: i) the "Elvo" and "Sesia" viaducts, two railway bridges on the new High Speed line Turin-Milan; ii) the "Chains Bridge" an historical suspended footbridge; iii) the "Tower of Matilde", an historical masonry bell tower.