PSI - Issue 78

Roberta Di Chicco et al. / Procedia Structural Integrity 78 (2026) 497–504

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Table 3. Damage levels for fragility curves. Damage level, D k

Description

Limit displacement

D1 D2 D3

Slight Moderate Near Collapse

0.7 d y 1.5 d y 0.5 (d y + d u ) d u 0.45 ln (μ)

D4-D5 Standard deviation (all levels)

Collapse

The results are reported in Figure 6.

a)

b)

Fig. 6. Fragility curves: (a) X-direction and (b) Y-direction.

4. Conclusions In this study, the municipality of Lavello (PZ) was investigated through the application of the CARTIS form, providing an exposure analysis of masonry buildings within the historic centre. The adopted methodology is based on interviews with qualified local technicians. The collected data support the development of municipal-scale vulnerability models and the promotion of seismic risk mitigation strategies. Particular attention was given to the analysis of the urban layout, focusing on recurring patterns of building aggregation. The main outcomes can be summarised as follows: • two masonry building types were identified in the urban context: the first, characterised by irregular masonry (65% of the sample), and the second, by regular masonry (35% of the sample). • the seismic behaviour of a masonry aggregate representative of Lavello’s building stock was examined using a mechanical-based approach. The reference model adopts a box-type behaviour, represented by a 3D equivalent frame where walls are interconnected through horizontal diaphragms. This modelling approach focuses on in-plane response, neglecting out-of-plane mechanisms as they are considered local phenomena of individual walls. The seismic response was evaluated through nonlinear static analysis, and the seismic-resistant system was characterised via capacity curves. The results show that the aggregate exhibits higher vulnerability in the Y-direction, while the stiffness of the capacity curves is comparable in both directions. Based on the overall results of the 24 analyses, the aggregate exhibits greater ductility in the X-direction. Finally, based on displacement capacity parameters obtained from the two worst pushover analyses, fragility curves in terms of spectral displacement were derived for both X and Y directions, using empirical formulations that relate damage state exceedance to specific displacement thresholds of an equivalent SDoF system. In terms of these fragility curves the behaviour is similar in the two directions.