PSI - Issue 44

Romina Sisti et al. / Procedia Structural Integrity 44 (2023) 1848–1855

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Romina Sisti et al./ Structural Integrity Procedia 00 (2022) 000–000

Another frequently encountered problematic case occurs when there are two symmetrical lateral chapels confused with the transept, especially if they are located close to the presbytery area, which give the church the cross plan typical of churches with a transept (Fig. 5b). It is considered useful to better define the transept in the compilation manual as a nave that is transversally disposed to the main longitudinal nave of the church, generally equal in height to that of the nave or in any case different from that of the lateral naves, giving the church the form of a Latin cross at floor level or at the roof one. Furthermore, in general, it would be useful to include some examples in the manual that highlight the most common errors and allow for a correct identification of the transept through an overall assessment of the conformation of the church, both internally and externally.

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Fig. 5. a) Sanctuary of SS Crocifisso, Ascoli Piceno (AP). b) Church of Santa Maria di Sitria, Sitria, Scheggia (PG).

7. Lateral naves The user manual defines the lateral naves as the "longitudinal space of a church between a row of columns and a wall". In some cases, the columns are not connected longitudinally but are simply the piers of arches arranged transversely to the church (yellow elements in Fig. 6a) and therefore there is no longitudinal response of the columns which is identified as the M7 mechanism. However, some technicians mark this mechanism as possible to describe generic damage to the columns. Another interpretative difference was found in churches with two naves. While the M7 mechanism associated with the central columns separating the two naves must always be marked as possible, with regard to the damage to the vaults of the two naves some technicians describe the vaults of one nave through the M8 mechanism (vaults of the main nave) and the damage of the other nave through the M9 mechanism (vaults of the lateral naves) regardless of the existence of structural differences between vaults of the two naves. Actually, M9 mechanism should only be considered when the vaults of the two naves differ in type, geometry or materials. 8. Lateral chapels Different interpretations by the technicians have been observed when there are chapels inside the church that, when look at from the outside, do not appear as independent structures adjacent to the main volume of the church. In this situation, many technicians identify the chapel from inside the church and consider all the related mechanisms as possible, regardless of the actual possibility of their activation. Instead, according to the proper approach, the inspection must be carried out both from inside and outside the church, evaluating which mechanisms can be activated. In Fig. 6b, for example, the overturning of the chapels (M22) is not possible, while the mechanism relating to the in -plane response (M23) can be used to describe the damage of the transversal walls of the chapels. Another problem arises when a series of chapels is present on the side of the main nave. In these cases, the chapels could be evaluated as a lateral nave, characterized by greater transversal stiffness due to the presence of the separation walls between the chapels; alternatively, they can be described through the mechanisms relating to chapels. While the first approach does not make it possible to quantify the damage to the transverse walls, it describes better the longitudinal walls that separate the main nave from the chapels, which are more similar to a colonnade with clerestory than to the lateral wall of a church with chapels.

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Fig. 6. a) Diagram of a church with a series of three transverse arches and the church of S. Bernardino in Montegallo, Ascoli Piceno (AP). b) Church of S. Maria della Piaggiola in Gubbio, (PG).