PSI - Issue 44

Sergio Ruggieri et al. / Procedia Structural Integrity 44 (2023) 1964–1971 Sergio Ruggieri et al./ Structural Integrity Procedia 00 (2022) 000–000

1969

6

Source

Feature

B1

B2

Structural typology

RC

RC

Number of units

1 5

1 7

Number of storeys

Presence of pilotis floor

No No No No No No Flat Yes Yes Yes

No No No

Presence of basement floor

Presence of superelevation floor

Type of roof floor Presence of vaults

Flat

VULMA

No No

Presence of visible seismic details

Presence of higher ground floor

Yes Yes Yes Yes

Presence of overhangs

Regularity in-plan

Regularity in-height

Census database

Year of construction

< 1980

1980-2008

CTR

Base area

~ 200

~ 400

Table 2. Varied geometrical and mechanical parameters for the phases of simulated design, modelling and analysis Type of parameter Parameter B1 B2

Year of construction < 1980

1980-2008

Localization

Medium seismicity

Medium seismicity

General

Pilotis

No No

No

Higher ground floor

Yes

Geometrical

Number of storeys

5

7

Base area (m 2 )

[100 200 300]

[300 400 500]

Aspect ratio

[1:1 1:2]

[1:1 1:2]

Mechanical

σ c (MPa)

[4 5]

[6 7.5]

σ s (MPa)

140

220

σ m (MPa)

[1.5 2.5]

[1.5 2.5]

G (kN/m 2 ) Q (kN/m 2 )

Loads

5 2

5 2

Combining the parameters in Table 2, a total of 24 models for each building has been generated, according to the procedures described in Section 4. For B1, only one-directional moment-resisting frames are considered, while double orientation is assumed for B2. In order to investigate seismic fragility, all buildings have been analysed through cloud analysis, using 30 natural ground motion records with two horizontal components of medium seismicity level. Results have been recorded in terms of average spectral acceleration, AvgSa , as IM (computed from 0.1 to 3 s, with a step of 0.1 s) and maximum interstorey drift ( θ max ) as EDP. Fragility curves have been evaluated for ultimate limit states, ductile and brittle, where the latter is evaluated by automatically checking the shear level in columns. A single component criterion has been adopted for defining the achievement of the limit-states, assuming the ultimate rotation in the first column for ductile mechanisms and the shear failure in the first column for brittle mechanisms. Cloud analyses have been fitted through the power law approximation proposed by Cornell et al. (2002), and fragility curves for ductile and brittle limit states have been computed accounting for a fixed epistemic uncertainty of 20%. Fragility curves for building B1 and B2 are shown in Figure 3, in which they are reported in different scales of grey, for both brittle and ductile mechanisms. Also mean fragility curves have been estimated, obtaining for B1 a median of 0.162