As many masonry domes, the dome of the Basilica of S. Maria Assunta in Carignano in Genoa, designed by Galeazzo Alessi and built in the XVIth century, exhibits a relevant crack pattern, consisting mainly of meridian cracks, which puts forward the issue of its safety. Based on Static and Kinematic Theorems of Limit Analysis, a simplified procedure for the assessment of the dome, useful to understand the overall structural behavior, is discussed first looking to kinematically admissible mechanisms and to equilibrated stress fields; the obtained equilibrium states are compared to those from a non-linear FEM analysis showing a good agreement. Due to the high redundancy of the structure, this latter issue is dealt with reducing the unknowns to the internal forces in key sections of the dome so that the mechanical response of the dome can be easily described and discussed. The procedure allows the assessment of the dome out- lining that: (i) the drum takes part in the collapse mechanism, so that kinematical analysis of the dome only may be not conservative; (ii) hoop ties in the drum, close to the base of the dome shells, plays a crucial stabilizing role; (iii) some parts of the structure, among which the ones prone to environmental degradation, may be crucial for the safety of the dome.
A simplified assessment of the dome and drum of the Basilica of S. Maria Assunta in Carignano in Genoa
A. Bacigalupo;BRENCICH, ANTONIO;GAMBAROTTA, LUIGI
2013-01-01
Abstract
As many masonry domes, the dome of the Basilica of S. Maria Assunta in Carignano in Genoa, designed by Galeazzo Alessi and built in the XVIth century, exhibits a relevant crack pattern, consisting mainly of meridian cracks, which puts forward the issue of its safety. Based on Static and Kinematic Theorems of Limit Analysis, a simplified procedure for the assessment of the dome, useful to understand the overall structural behavior, is discussed first looking to kinematically admissible mechanisms and to equilibrated stress fields; the obtained equilibrium states are compared to those from a non-linear FEM analysis showing a good agreement. Due to the high redundancy of the structure, this latter issue is dealt with reducing the unknowns to the internal forces in key sections of the dome so that the mechanical response of the dome can be easily described and discussed. The procedure allows the assessment of the dome out- lining that: (i) the drum takes part in the collapse mechanism, so that kinematical analysis of the dome only may be not conservative; (ii) hoop ties in the drum, close to the base of the dome shells, plays a crucial stabilizing role; (iii) some parts of the structure, among which the ones prone to environmental degradation, may be crucial for the safety of the dome.
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