PSI - Issue 44

Romina Sisti et al. / Procedia Structural Integrity 44 (2023) 1380–1387 Romina Sisti et al. / Structural Integrity Procedia 00 (2022) 000–000

1386

7

‘moderate damage’, while for ‘severe damage’ the most critical one is the overturning of the apse, M16, but it is worth noting that for ‘severe damage’ the curves show dampened differences. For the bell tower (Fig. 5d), it is interesting to note that the mechanisms are always less vulnerable than the macro element for all the three damage conditions, with the only exception of the mechanismM26, related to the overturning of standing out elements, that at ‘severe damage’ becomes more vulnerable than the macro-element.

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Probability

Probability

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

PGA [g]

PGA [g]

a) Façade (continuos lines, squared markes) M1 (dash-dotted lines, x markers) M2 (dashed lines, round markers ) M3 (dotted lines, triangural markes)

b) Principal nave (continuos lines, squared markes) M5 (dash-dotted lines, x markers) M6 (dashed lines, round markers) M8 (dotted lines, triangural markes) M19 (dash-double dotted lines, cross markers)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Probability

Probability

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

PGA [g]

PGA [g]

c) Apse (continuos lines, squared markes) M16 (dash-dotted lines, x markers) M17 (dashed lines, round markers) M18 (dotted lines, triangural markes ) M21 (dash-double dotted lines, cross markers)

d) Bell tower (continuos line, squared markes) M26 (dash-dotted lines, round markers) M27 (dashed lines, x markers) M28 (dotted lines, triangural markes)

Fig. 5. Fragility curves related to macro-elements (continuous lines) vs. fragility curves related to mechanisms (dash/dotted lines). Black color identifies the slight damage, dark grey the moderate damage, light grey the severe one. Markers indicate the observational data. 5. Conclusion The 2016-2017 Central Italy earthquakes strongly affected unreinforced masonry churches, especially with the activation of local mechanisms rather than with a global behavior. For this reason, the vulnerability assessment of churches should be mainly based on the identification of the damage associated to possible local mechanisms. In this paper, the data collected for a sample of 2884 churches during the long emergency phase following the six main shocks were analyzed with the aim of elaborating empirical fragility curves. These are based on the damage probability matrices obtained from the statistical elaborations collected in the A-DC forms. While the fragility curves for the churches generally refer to the damage induced by the seismic event through the estimation of a global index, damage was herein assessed also for the single macro-elements and for the mechanisms contributing to the damage to the most recurrent macro-elements. The availability of fragility curves for a particular type of macro-element or