Frequency tracking and FE model identification of a masonry tower

The historic bell tower of the San Vittore church in Arcisate (Varese) has been studied by Politecnico di Milano since 2007. After a brief description of past operational modal tests and FE modelling, the paper focuses on the results provided by a simple dynamic monitoring system installed inside the tower for several months. The modal identification was performed using the data-driven Stochastic Subspace Identification technique and the estimated natural frequencies turned out to exhibit clear dependence on temperature. Subsequently, the modal frequencies were used to identify some uncertain structural parameters of the FE model, using the simple method proposed by Douglas and Reid (1982). Originally-identified and temperature-removed modal frequencies were used as experimental references in the identification of structural parameters and the two sets of optimal parameters (with and without the temperature effect) are presented and discussed.