Survey, seismic input and structural modeling of the "Regina Montis Regalis" basilica and large elliptical dome at Vicoforte, northern Italy

This paper illustrates the results, up-to-date, of a wide investigation and research program aimed to establish new advanced bases for the conservation of the “Regina Montis Regalis” Basilica of Vicoforte, in Northern Italy. The Basilica is a building of great historical, architectural, and structural significance, owing its fame primarily to its big masonry elliptical dome, the world’s largest of this shape. The dome-drum system has suffered over the years from significant structural problems, partly due to soil settlements, and, to a large extent, arising from its bold structural configuration. In 1983, concerns over the severe settlement and cracking phenomena affecting the structure prompted the decision to undertake inspection, monitoring and strengthening interventions, operated between 1985 and 1987 and followed by the set up of a monitoring system for the measurement of strains, stresses and crack propagation. In the last decade, a new research and investigation program was established, with the scope of improving the knowledge of the construction, interpreting the cracking phenomena through an advanced non linear modelling in the static domain, estimating the structural safety under gravity loads on the basis of limit analysis, and updating numerical models through the comparative examination of the structural response in the dynamic domain. Currently, the program addresses the evaluation and reduction of the seismic risk of the monument. At this purpose, an in-depth, site-specific seismic hazard assessment study has been conducted to define the proper seismic input for the analyses. The program is developed in coordination with national conservation institutions, considering Vicoforte Basilica as a notable case study for the application and assessment of the guidelines recently formulated at national and international level for the protection of cultural heritage in seismic regions. While the first part of this wide program was already reported at SAHC 2006 and in the literature, the paper concentrates on the last developments concerning dynamic and seismic analyses.