History-based assessment of the dome of the Basilica of S. Maria of Carignano in Genova

ABSTRACT. The paper discusses the assessment of the dome of the Basilica of S. Maria of Carignano in Genoa, designed by Galeazzo Alessi in the XVIth 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, 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, that nowadays puts forward the need for 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. Besides, historical data are used to setup a non linear incremental FEM procedure, referred to a slice (1/16th) of the structure due to symmetry conditions, that 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.