Evaluation of the seismic capacity of cultural heritage in case of aggregate buildings: the Castle of Rosignano Marittimo

The partitioning of masonry buildings in Structural Units (SUs), or aggregate of Structural Units, is a useful tool to simplify the analysis of the buildings and the study of static and seismic vulnerability. However, this allocation is affected by uncertainties, simplification, and sometimes unavoidable miscalculation due to the directionality of this subdivision. This procedure exposes the results to discrepancies due to the way the building is divided. The Castle of Rosignano is emblematic. In this paper, the dependence of the results on how the Structural Units are considered is analyzed, as well as the role of structural in plan and elevation irregularities on various SUs and their combination. Non-linear static analysis corresponding to different distributions of the building in Structural Units, the uncertainties about material properties, and different directions of the seismic action are analyzed, and the respective results are discussed here. A simplified approach, for the study of aggregate buildings on an urban scale, is based on the so-called “tabular method”. Several Authors proposed and improved similar methods applied to different urban contexts. A comparison of simplified methodologies with the results of the detailed FEM analysis is also discussed and presented here. Finally, a simplified approach is proposed based on the regularity parameter of the building in aggregate. Taking the evidence from FEM analysis as a physical-mechanical base, the authors propose the quantitative definition of irregularity parameters and the use of them to determine the building vulnerabilities. The proposed procedure aimed to be a practical tool to determine, in an expeditious manner, the seismic capacity of a masonry building in aggregate. The model proposed in this paper, applied to the case of the study of Rosignano Marittimo (a typical situation of aggregate building in a historical context in Tuscany, Italy) shows emblematic results that can be extended to analogous configuration.