PSI - Issue 78

Emanuele Maiorana et al. / Procedia Structural Integrity 78 (2026) 57–64

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yielding a Young's modulus (E) of 1750 N/mm² - within the range of 1200-1800 N/mm² specified in Table C8.5.I [8]. Notable observations during wall investigations included the refectory's barrel vault construction, comprising structural arches with "arelle" infill panels spanning between them.

Fig. 10. Tests in the walls.

The wooden crosspieces at the vault base were found to be hollow, serving only decorative purposes while accommodating electrical wiring and providing diffuse lighting. More broadly, the wall system exhibits discontinuities reflecting successive modifications over time, with several areas showing significant cracking. Analysis of the building's plan configuration revealed that in certain locations, transverse walls are spaced at distances where their interaxis-to-thickness ratio prevents effective constraint against out-of-plane overturning mechanisms. Field observations across multiple floors identified non-structural wall partitions lacking proper load transfer capabilities. This condition presents particular seismic vulnerability due to the absence of direct foundation connections for shear stress transmission. Considering the available documentation and the investigations conducted, a knowledge judged still limited was obtained with regard to the extension of the surfaces involved, the geometry of the main structural elements (pillars, partitions and beams) and secondary elements (floors and roofs), the construction details and the reinforcement of the sections. The level of knowledge is therefore classifiable as LC1 knowledge level (§ 8.5.4 [7]): this involves carrying out the safety checks adopting a confidence factor FC=1.35 (§ C8.5.4.2 [8]). The increase in knowledge level, classified as LC2, for the parts of the complex used for school purposes, was postponed to a later date. For the purposes of seismic vulnerability assessment, a dynamic linear analysis was conducted, with a load-bearing structure mainly in masonry, consisting of: • in determining the frequencies and modes of vibration of the building (modal analysis). All modes with significant participating mass are considered: single participating mass greater than 5% and a number of modes whose total mass is greater than 85%; • in the calculation of the effects of the seismic action, represented by the design response spectrum, for each of the identified vibration modes; • in the combination of these effects (“SRSS”). For the seismic analysis of local mechanisms, limit analysis methods for the equilibrium of masonry structures were used, taking into account, even if in an approximate form, the compressive strength, the masonry texture, the quality of the connection between the masonry walls, the presence of chains and tie rods. In the presence of floors with finite stiffness, the response can be obtained by inserting the mechanical characteristics of each horizontal floor into the building model, where reasonably identifiable; in this case, the floors help prevent the premature collapse of the weakest walls and the connections between floors and walls are generally less stressed than in the case of infinitely rigid floors. The magnitude of the horizontal forces acting on the building's seismic-resistant system was determined by analyzing the loads and estimating the weight of all structural and non-structural components. 5. Seismic vulnerability assessment