Oma Dynamic Identification Of A Masonry Chimney With Severe Cracking Condition

The results of the ambient-vibration based investigations carried out to assess the structural behaviour of masonry are presented. The chimney, dating back to 1950, and about 24 m high, is characterised by the presence of major cracks on the northeast facade. The assessment procedure includes full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modelling and dynamic-based identification of the uncertain structural parameters of the model. Different materials were tested according to the Young’s modulus (strong, middle or weak masonry) and two types of models, with or without crack, in order to calibrate the behaviour of the numerical model. Finally, the results showed that the effect of the crack does not produce significant changes in bending modes. However, torsional stiffness decreases significantly, and therefore, torsional modes are lower.