Dynamic identification and seismic behaviour of the Ghirlandina tower in Modena (Italy)

This paper presents a simplified vulnerability assessment method for masonry towers taking into account the soil-structure interaction. The soil-structure interaction model is based on in situ investigations, defining a detailed soil profile and the relevant mechanical parameters, aimed at capturing the expected behaviour during seismic events. In particular an upper and lower soil stiffness, appropriate for low and high intensity seismic events have been considered, and a validation of upper values was also performed throughout an identification analysis, based on vibration records of the tower. Limit analysis method was then applied to identify the collapse mechanisms geometry, under the assumption that masonry is a no-tension material. This implies that at the limit of overturning, a part of the masonry will remain attached to the base and a stress-free diagonal surface of fracture will form.