PSI - Issue 44

Luca Umberto Argiento et al. / Procedia Structural Integrity 44 (2023) 1388–1395 Luca Umberto Argiento et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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overturning moment. Conversely, th e influence of λ s is strictly related to the thickness of sidewalls s t that increases the role of frictional resistances exerted by the sidewalls (Casapulla and Argiento 2016).

Table 4. Correlations between identified a-dimensional geometric parameters and homogeneous classes of vulnerability. Homogeneous class of vulnerability Slenderness parameter Free rocking façade High vulnerability (red curves) λ f ≥ 13 .5 Medium vulnerability (yellow curves) 11.5 < λ f < 13.5 Low vulnerability (green curves) λ f ≤ 11 .5 Façade with restrained condition High vulnerability (red curves) λ s ≥ 12.5, λ l ≥ 11.5 Medium vulnerability (yellow curves) λ s < 12.5, λ l ≥ 11.5 or λ s ≥ 12.5, λ l < 11.5 Low vulnerability (green curves) λ s < 12.5, λ l < 11.5

3,5

3,5

High vulnerability Medium vulnerability Low vulnerability

High vulnerability Medium vulnerability Low vulnerability

3

3

2,5

2,5

2

2

a [m/s 2 ]

a [m/s 2 ]

1,5

1,5

1

1

0,5

0,5

0

0

0

0,1

0,2

0,3

0,4

0,5

0,6

0

0,1

0,2

0,3

0,4

0,5

0,6

d [m]

d [m]

a)

b)

Fig. 4. Capacity curves for 14 churches divided in three different vulnerability class for the: a) free rocking and b) restrained condition.

Finally, it is interesting to note that when the frictional resistances are taken into account, the following churches change the vulnerability class: • SRO: from high vulnerability to medium vulnerability class due to the small length of the façade and the large thickness of the sidewalls; • CA: from medium vulnerability to low vulnerability class due to the small length of the façade and the large thickness of the sidewalls; • SOC: from low vulnerability to medium vulnerability class for the large length of the façade; • SFA: from medium vulnerability to high vulnerability due to the large length of the façade and the small thickness of the sidewalls. In future works, ISA (incremental static analysis) curves will be developed based on such kinds of homogenous vulnerability classes with the aim of implementing analytical fragility curves to be compared with the empirical/observational ones present in the literature (Cescatti et al., 2020). 5. Conclusions In this paper, the seismic assessment of the simple rocking mechanism of 14 façades of masonry churches located in the Ischia Island was addressed according to the capacity spectrum method. The rocking motion of these façades, slightly damaged by the seismic event occurred in the island in 2017, was analysed with reference to three limit states, i.e. rocking initiation (LS0), moderate rocking (LS1) and near collapse (LS2) conditions. An advanced macro-block model accounting for frictional resistances was adopted to take into account the interlocking of the façades with the sidewalls.