The recent seismic events occurred on May 20 and 29 have been characterized by the presence of low frequency ground motions, with relevant vertical components, as typical of near field earthquakes. As a consequence, from a structural point of view, structures having natural periods greater than those typical of ordinary buildings -such as precast concrete industrial structures and cultural heritage constructions (masonry churches, bell towers and castles)- have been severely damaged. Moreover, the area along the Po river has historically been the seat of agricultural transformation activities, like for instance the production of sugar from beets and tomato sauce. This kind of plants is typically characterized by the presence of masonry chimneys, which have shown to be particularly vulnerable to the effect of the earthquake. As a matter of fact, a number of chimneys near Ferrara have been so severely damaged, that their demolishment was required for public safety (e.g. the “Pandurara” chimney in Bondeno and the chimney in Santa Bianca).

This work is devoted to the study of a masonry chimney, built at the beginning of the 19^th century and further modified in the fifties, located inside the “Polo Scientifico-Tecnologico” of the University of Ferrara, previously a sugar factory. The chimney is axial symmetric, 50 m tall and presents at the base an internal radius equal to 2 m, with an external radius equal to 3,25 m. After the 20^th of May shake, the structure presented evident diagonal cracks at an altitude of approximately 46 m and represented a danger for the whole surrounding area. Therefore, its height has been recently reduced of 12 m with a controlled demolishment.

In the paper, the results of different kinds of advanced numerical analyses, performed to have an insight into the causes at the base of the formation of the cracks, are critically discussed and compared. The numerical investigations comprise modal analyses conducted by means of either 1D and 3D Finite elements models, a number of non-linear static (pushover) analyses performed employing the DIANA code with different force distributions (the first mode activates a mass of about 22% only) and non-linear dynamic analyses. These latter simulations have been performed by means of a specifically developed 1D program employing linear elastic or rigid beams connected by non-linear elements, whose mechanical properties have been derived by homogenization techniques, where the non elastic deformations are lumped. Finally 2D non-linear dynamic simulations assuming previously developed rigid body elements connected by non-linear springs are presented.