PSI - Issue 78

Ingrid Boem et al. / Procedia Structural Integrity 78 (2026) 457–464

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5. Validation The validation of the Fisrtep-M_PRO procedure has been carried out with reference to several case studies (four of which are summarized in Fig.3, as examples), by comparing the simplified capacity curves with those obtained from more refined pushover analyses based on the equivalent frame model of the entire building, using lumped plasticity hinges (the software MidasGEN has been used for these analyses). In general, a good correlation emerges between the curves.

Fig. 3. Examples of validation of the simplified procedure. Thick and thin lines are the capacity curves referred, respectively, to the Firstep M_PRO procedure and to the MidasGEN equivalent frame pushover analysis; solid and dashed lines refer to RM and URM configurations. 6. Results The fragility curves are plotted in Fig.4, divided in sub-typologies according to the number of storeys and age of construction; the median values of resisting ground acceleration and the dispersions are also reported. Clearly, for certain groups, the sample size is too limited (1-to-3 buildings) to consider the results significantly representative. However, some interesting conclusion can be drawn:  the seismic vulnerability related to a certain DL generally increases when moving from single-storey to multi-storey URM buildings, even though no remarkable differences emerge between 2 and ≥3 storey structures. This is likely attributable to the higher seismic mass of multi-storey schools (which results in increased seismic demand), not matched by a sufficient increase in the percentage of resisting masonry (which improves the capacity). Moreover,