Antonio Brencich

History-Based Assessment of the Dome of the Basilica of S. Maria of Carignano in Genoa

This article discusses the assessment of the dome of the Basilica of S. Maria of Carignano in Genoa, designed by Galeazzo Alessi in the 16th century. The access to the private archive of the Sauli Family allowed a detailed history of the Basilica to be reconstructed clarifying several crucial aspects of the structure: the actual depth of the foundation system, the materials of the load bearing structure, mainly of the dome and of the drum, and the actual building sequence. The restoration works (steel hoop) carried out in the past decades, discovered by means of the historical research, are related to the severe crack pattern of the dome, which today necessitates a detailed insight into its mechanical response. It is showed that historical information is the key for understanding several issues that a “technological” engineering approach would leave unsolved. In addition, historical data are used to setup a non-linear incremental finite element model (FEM) procedure, referred to a slice (a ratio of 1/16) of the structure due to symmetry conditions, which is able, in spite of its reduced computational demand, to show that the dome response is strictly related also to the drum features, thus explaining cracking and the role of hooping stresses (and ties) in the global equilibrium. Some issues for the retrofitting of dome-like structures are discussed.

On the Statics of the Dome of the Basilica of S. Maria Assunta in Carignano, Genoa

The paper deals with the dome of the Basilica of S. Maria Assunta in Carignano in Genoa, designed by Galeazzo Alessi and built in the sixteenth century, for which meridian cracking, rather common in masonry domes, requires the assessment of the dome. In order to set a general procedure for the assessment this structures, limit analysis approaches are here discussed and compared. On the basis of classic limit analysis, local (dome only) and global (dome-drum system) collapse mechanisms are considered considering the different behaviour of several structural elements (lantern, shells of the dome, drum, colonnade). A static (safe theorem) and a kinematic approach are applied to the structure by means of equilibrium limit conditions and kinematically admissible collapse mechanisms. Comparisons between the obtained results are carried out so as to: (i) discuss a general approach to the assessment of dome-drum systems based on both numerical tools and standard limit analyses approaches; (ii) provide a first glance in the assessment of the dome.