PSI - Issue 84

Manuel Capogna et al. / Procedia Structural Integrity 84 (2026) 717–724

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structural conception primarily focused on resisting gravity loads, with a purely conventional and simplified approach to horizontal actions. The identified configuration consists of a reinforced concrete frame structure with cast-in-place hollow clay tile and concrete floors; however, the arrangement of the resistant frames is effective mainly in a single direction, leaving the structure intrinsically vulnerable to seismic actions acting orthogonally to that orientation (See Fig.1). a c

b

Fig. 1. (a) Foundation structural layout; (b) Typical floor structural layout; (c) 3D Model.

The definition of the mechanical parameters of the materials was conducted with the objective of achieving Knowledge Level LC2, defined as Adequate Knowledge according to NTC 2018. This level was reached through a careful synthesis of the original design documentation and a specific in situ testing campaign involving both destructive and non-destructive tests. In determining the properties of the concrete, particular attention was paid to the intrinsic variability of the materials used during the era of construction; as highlighted by statistical analyses of Italian production from that period, concretes produced between the 1960s and 1970s often exhibit significant dispersion in strength values, influenced by construction site practices that were not always standardized (G. M. Verderame et al., 2001). The results of sclerometric tests and core samples conducted on the school complex allowed for an estimation of mean concrete strength consistent with these bibliographic findings. Regarding the reinforcement, direct inspections and the analysis of period certificates confirmed the use of high bond steel bars of the Feb38k type. Technical literature emphasizes that bars produced between 1950 and 1980 possess mechanical characteristics conditioned by the rolling processes of the time, with yield and ultimate strength values showing a variability that must be appropriately weighted in safety verifications (Gerardo Verderame et al., 2001; Verderame et al., 2011). Specific studies on the properties of steels used in the existing building stock have also demonstrated that the ductility of such bars can be lower than current standards, thereby conditioning the plastic deformation capacity of the structural elements (Gerardo Verderame et al., 2001). Consistent with the LC2 level