Long-Term Vibration Measurements to Enhance the Knowledge of a Historic Bell-Tower

The results of the long-term vibration monitoring program, carried out on the bell-tower of Santa Maria del Carrobiolo in Monza (Italy), are reported in the paper. The dynamic monitoring was motivated by the weak structural layout of the historic building, with two fronts of the tower being supported by the load-bearing structures of the apse and South aisle of the adjacent church. The main results of the dynamic monitoring for a period of one year highlight distinctive behavior of the bell-tower, such as the frequency veering exhibited by the lower modes with increased temperature. Subsequently, in order to mitigate the contributions of the environmental effects on resonant frequencies, the application of the multiple linear regression (MLR) and the principal component analysis (PCA) tools have been investigated.