Operational Modal Analysis of Complex Buildings with and Without Structural Joints

Buildings with complex geometry are very often a challenge in the process of dynamic identification since they are characterized by many vibration modes, sometimes even too closely-spaced to be clearly identified. Such modes may be difficult to distinguish in modal tests and lead to difficulties when they need to be automatically identified within the structural health monitoring framework. This work deals with the challenges faced for the dynamic identification through operational modal analyses of a complex hospital building. The whole building is composed by many structural bodies with the same height, same structural typology, and built in adjacent to each other, constituting a quite complex plan shape geometry. In the entire building, an intensive experimental campaign was made, and a spread dynamic seismic monitoring system has been installed to monitor the structure both during operational conditions and under extreme excitations, as, for instance, earthquakes.