PSI - Issue 78

Ebrahim Aminifar et al. / Procedia Structural Integrity 78 (2026) 1466–1473

1468

3. Statistical analysis and definition of the reference sample 3.1. Plan layout

Following regional stratification, a morpho-typological classification was conducted to determine the prevailing architectural forms. Five main typologies in terms of plan layouts were identified: rectangular, Latin cross ( commissa ), Latin cross ( immissa ), Greek cross, and central-plan. Their distribution across the six regions is summarized in table 1. The analysis revealed a strong predominance of the rectangular typology. Of the 1,781 entries, 1,566 (approximately 88%) were classified as rectangular, with the layout being the dominant form in all regions except Umbria-Marche. However, it must be highlighted that this information was available just for a limited portion of the entire sample, thus where they were not systematically present, the subset referred to a single earthquake swarm was neglected.. In general, the prevalence provides the rationale for focusing the remainder of the study on rectangular churches. The selection of a single dominant typology improves typological consistency and reduces variability due to architectural heterogeneity, thereby strengthening the statistical validity of clustering procedures and geometric ratio analyses.

Table 1. Typological classification of the churches based on plan layout

Typology Rectangular 957 (90.80 %)

Region

Total

Latin ( Commissa )

Latin ( Immissa )

Greek

Central 0 (0%)

Central Italy

48 (4.55 %)

49 (4.65 %)

0 (0%)

1054

L’Aquila

451 (87.40 %)

14 (2.71 %)

36 (6.98 %)

8 (1.55 %)

7 (1.36 %)

516

Ischia

12 (75 %)

0 (0%)

3 (18.75 %)

0 (0%)

1 (6.25 %)

16

Piemonte

90 (78.95%)

0 (0%)

24 (21.05%)

0 (0%)

0 (0%)

114

Salò

56 (96.55 %)

0 (0%)

2 (3.45 %)

0 (0%)

0 (0%)

58

Umbria/Marche

0 (0%)

0 (0%)

23 (100 %)

0 (0%)

0 (0%)

23

Total

1566 (87.92%)

62 (3.48%)

137 (7.70%)

8 (0.45%)

8 (0.45%)

1781

To further refine the morphological classification, a detailed survey was conducted to assess their internal nave configurations. The analysis categorized buildings into four structural layouts: single-nave, two-nave, three-nave, and single- cell configurations. The term “single - cell” refers to small, undivided ecclesiastical volumes, typically rural chapels that lack a clearly articulated nave. The distribution of nave configurations across the rectangular subset is summarized in Fig.2. The results confirm the predominance of the single-nave layout, which accounts for 1,325 out of 1,566 rectangular churches, representing over 84% of the rectangular subset and approximately 74% of the total dataset. Central Italy (837 churches) and L’Aquila (362 churches) constitute the principal concentrations of single -nave examples, while smaller numbers are documented in Piemonte, Ischia, and Salò. By contrast, two-nave (36 churches), three-nave (186 churches), and single-cell structures (24 churches) represent minor components of the dataset. The statistical dominance combined with the structural homogeneity and architectural clarity of the single-nave typology justifies its selection as the analytical core of the study. Focusing on the morphologically consistent group enables a more robust interpretation of clustering results, geometric ratio trends, and material-related performance indicators . 3.2. Typological features of Single-Nave Churches To support the classification and seismic vulnerability modeling of Italian single-nave churches, a detailed investigation was conducted on key typological and geometric parameters derived from dataset of 1,325 buildings, as defined in the previous section (i.e. one-nave churches). The results are provided in Fig. 2.