PSI - Issue 78

Francesca Mattei et al. / Procedia Structural Integrity 78 (2026) 2007–2014

2011

of Risk IR = H + V + E, where H, V and E are the classes of Hazard, Vulnerability and Exposure, respectively. In the present paper, the authors focused on level 1, defining Seismic Hazard, Vulnerability and Exposure Classes for the historical center of Cosenza, following the method previously mentioned. To obtain Seismic Hazard Class H a preliminary study on the seismic history of Cosenza was conducted [Stucchi et al. (2015)]. The city was in fact subjected to more or less violent earthquakes that had as their epicentre either neighbouring areas or areas in Central and Southern Italy. In the specific, Cosenza suffered consequences of varying severity from these events (occurred in 1855, 1991, 1965, 1996), but the most significant of which occurred during the 1905 earthquake with its epicenter in Messina. Then the maximum horizontal ground acceleration ‘ a g ’ considering rigid and plane soil conditions for return period equal to 475 years, as reported in following Table 1 was deducted, that is equal to 0.272 [Meletti et al. (2004)]. Since Cosenza has an a g equal to 0.272g, the parameter H corresponds to 4 (Table 1).

Table 1. Seismic Hazard Class. Seismic Hazard a g

H

High

ag > 0.200g

4 3 2 1

Medium-High Medium-Low

0.150g < ag ≤ 0.200g 0.125g < ag ≤ 0.150g

Low

ag ≤ 0.125g

Vulnerability Class V is deducted calculating a vulnerability index Iv that is as a function of construction period, structural type and building height and urban vulnerability, construction type and history of seismic classification (just as an example). In the specific Iv = Icp + Ist + Ih + Iuv + Ispt + Isc, where: • I cp is the construction period index, that is obtained according to the period value Vp, depends on the number of buildings belonging to different construction periods. • I st is the structural type index; • I h is the height index; • I uv is the urban vulnerability index; • I spt is the specialist type index; • I sc is the seismic classification index. For the determination of V p (and then of I cp ), was considered that there are n.8546 buildings before 1945 all built before 1945, therefore is obtained a value of V p equal to 100, giving Icp = 4 (Table 2).

Table 2. Construction period index. Vp Icp Vp ≥ 90 4 70 ≤ Vp < 90 3 50 ≤ Vp < 70 2 Vp ≤ 50 1

The structural type index I st depends on the ratio of reinforced concrete (RC) buildings to the total, equal to 0 for historical center of Cosenza, formed by masonry buildings (Table 3).

Table 3. Structural type index. Ratio of RC buildings to total

Ist -1

> 75% ≤ 75%

0

The height index I h depends on the height value V h depending on the number of buildings having the same floors