A geometric approach to evaluate the safety of mansory constructions: the case study of St. Scolastica Abbey in Subiaco

The paper presents the structural assessment of the neoclassical Church at the Abbey of St. Scholastica in Subiaco, located close to Rome, Italy. Here the Renaissance and gothic layers, along with the neoclassical reconstructions from 1769, are uncovered to study their role in the overall stability of the structure. With the aid of historic references, on-site visual inspection and a laser-scanning survey conducted, an understanding of the geometrical and structural configuration that defines this historic construction was established. Adopting an assessment methodology based on limit analysis and graphic statics, the structural evaluation was conducted for each of the individual structural elements i.e., by isolating the arches, vaults, buttresses, and for the integrated system as a whole. Through this analysis, the Geometric Factor of Safety (GFS) related to the global equilibrium of the church's section was calculated. Without any claim of comprehensiveness in the case study, this work stands as a paradigmatic example for people intending to check the stability of historical buildings. In fact, the purpose of the research is to present, through a case study and with the aid of limit analysis approach, how the use of GFS can characterise the degree of safety in a simple and straightforward manner.