Operational Modal Analysis and FE modelling of a masonry tower

Within a wide program of structural assessment, ambient vibration modal testing and analysis were applied to an historic masonry bell-tower, about 37. 0 m high and placed in the small town of Arcisate (about 80 km far from Milan, Italy). Ambient vibrations induced by wind, micro-tremors and swinging of bells were recorded and 5 normal modes were identified in the frequency range 0-6 Hz by using two complementary techniques: the Frequency Domain Decomposition (frequency domain) and the Stochastic Subspace Identification (time domain). The identified modal parameters, together with geometrical, crack pattern survey and ND test information were used to calibrate a 3D F. E. of the tower.