PSI - Issue 29

Michele Paradiso et al. / Procedia Structural Integrity 29 (2020) 63–70 Paradiso, Conte and Prosperini / Structural Integrity Procedia 00 (2019) 000 – 000

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2. Survey, analysis anddiagnosis For both the exterior and the interior, it was decided to carry out a digita l survey using laser scanner technology, with which we obta ined a safe and reliable model with an accuracy that has not been achieved so far. The internal areas of the former church of San Lorenzo lent themselves well to the use of this technology. The presence of large spaces, the multitude of double-height walls, the lack of the level of the intermediate floor, the richness of the seventeen wooden trusses and the peculiarityof the vaults of the stairwell are a ll va lid reasons for the acquisitionof deta ils through high-resolution three-dimensional scanning. Thanks to the digital survey it was possible to study all the seventeen trusses on theroof. The trusses havea wheelbaseof 3.2 m. andcover a spanof about 20m. This is the reason why the chain turns out to be a chain composed of threeparts with link s to the dart of Jupiter. As far as what the underground rooms are concerned, direct surveys have been conducted. The crypt below the level of the pavement of the chapel of the Holy Trinity was easily identified by the access guaranteed by a narrow brick sta ircase, partially preservedandhiddenby a plaque on the floor placed in front of thea ltar. The crypt occupies about 4.10 by2.4 meters. The wa lls and the vault, completely intact, have the decoration of a cross painted with red earth. The floor consists of a simple lime mortar spreaddirectly on the ground. This environment does not belong to the first compositionof the Church; Tracesof thechapel's wall pa intings, in fact, have been found in thespace between the wa lls of the vault and the east wall. In correspondence with the fact that the chapel of San Giovanni, demolished a t the end of thenineteenth century to make room for the constructionof thedome staircase, is the secondhypogeum environment. The investigation was not easy however a ground level arch perpendicular to the stairs is still visible. This seemed to be the entrance to a lower area which is currently completely covered by landfill and debris. The assumption is, therefore, tha t it could be the beginning of the second underground env ironment, which with the transformation of the church into a military district was filled with waste materia l in order to provide grea ter support for the newupper conformation. For the foundations, two essays were conducted in rela tion to the fifthdividingwall with respect to the main entrance, initia lly detected directly. The foundations were made up of sack masonry, with river gravel andcommon lime mortar. According to the analysis performed, there donot seem tobe anybends, so the thickness of the foundation structure corresponds to that of the upperwa lls.

Fig. 3. (a) Photo of the interior of the first underground room below the chapel of the Holy Trinity; (b) Reconstruction of t he arches of access to the chapels and of the large arched openings in the external wall on Via del Maglio, following the lesions in the masonry.

The pa thologies present in this buildingare probably mainly attributable to anthropogenic factors causedby the lack of maintenance over time and by the improper use of the premises; Recall that the church suffered from unrest and was not respected for its wea lth and beauty when it first became a military district and then a carpentry workshop. Other types ofweather (ra in andpollution) and thepresenceof animals join thesefactors. Another important causeof degradation can be a ttributed to rising humidity phenomena due to the presence of undrained groundwater and the absence of good bases for the factory. Surely the restora tion works in the 90s have allowed a considerable