Stability Analysis and Seismic Vulnerability of Large Masonry Domes

This research specifically deals with the issue of the stability of the dome of St. Francesco di Paola (1816) in Naples. It represents the largest in size and the most significant among the examples of Neapolitan Neoclassical architecture which arouses a great interest above all for its solid and impressive structure. The structural analysis is performed on Heyman's Theory of Limit Analysis for masonry structures and, particularly, on the traditional method that makes use of a static approach based on graphic statics and on the interpretation of thrust lines of stone arches. As known, displacements are common in historic masonry structures due, for example, to consolidation of materials, imperfections in construction or differential settlements in foundations. The structural method applied in this work does not aim to define the cause of these displacements but rather seeks to understand their influence in the stability of the construction. In this perspective, in addition to the static analysis, a kinematic analysis approach has been necessary to comprehend the range of possible movements of the masonry structure. Thus, the research of the dome minimum thrust has been checked both by static and kinematic approaches in order to assess the safety of the construction. Furthermore, the effects of earthquakes have been explored. By introducing horizontal forces proportional to the weight, it has been possible to assess the dome stability under horizontal actions and to determine the limit value of the dome inclination for which the masonry is still entirely compressed.