C. GENTILE, A. SAISI and L. BINDA Department of Structural Engineering, Politecnico di Milano, Milan, Italy

The dynamic characteristics of an historic masonry bell tower are investigated using full-scale testing and finite element analysis. The tower, about 74m high, is adjacent to the Cathedral of Monza (Italy) and exhibits major cracks on the western and eastern load-bearing walls. The experimental program includes ambient vibration tests of the tower; full details of the dynamic experimental procedures, instrumentation and data analysis techniques are reported. In the theoretical study, vibration modes were determined by using a 3D finite element model. The comparison between measured and predicted modal parameters was then used to verify the assumptions adopted in formulating the model. Specifically, a good match between theoretical and experimental modal parameters was reached for relatively low stiffness ratios of the model in the zones of the Tower which were most damaged.