The aim of this research is the structural study of the hemispherical dome of San Francesco di Paola in Naples and, in particular, the evaluation of its degree of seismic safety not considering the role of the supporting structures. The methods we adopt are based on the determination of a class of purely compressive stress regimes, which are balanced with the load. Within the unilateral model for masonry (Heyman’s model), the mere existence of such a class is a proof that the structure is safe; members of this class can be used to assess the geometric degree of safety of the structure and to estimate bounds on the thrust forces exerted by the structure on its boundary. The analysis has been performed, by using both the graphical method and the membrane approach. The methodological innovation consists in the use of both the analytical and the traditional methods of graphical calculation of masonry structures, considering both vertical and horizontal loads. As a result of our analysis, we conclude that the sole dome can sustain a horizontal load of 0,577 g.
