PSI - Issue 44

Michele Angiolilli et al. / Procedia Structural Integrity 44 (2023) 2074–2081 M. Angiolilli et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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this paper, the condition prior to the 2016 earthquakes is investigated. Please refer to Angiolilli et al. (2022a) for further information on the case study. Table 1 lists the main characteristics of the URM aggregates under investigation.

Table 1. Main features of the two case studies (*maximum dimensions of the entire aggregate)

Nr. of storeys

Min/max Interstorey heights [m]

Dimension in plan [m]

Site

Era

Plan configuration

C-shaped unit within a L shaped aggregate

Catania 1840s 3

4.46 - 5.84

43 x 39

*

Visso

1920 3-4

Row housing

2.1 - 3.9

35.7 x 17.7 *

The structural model of the case studies was developed according to the equivalent frame (EF) modelling approach implemented in the Tremuri software (Lagomarsino et al. 2013). Figure 1 illustrates also the EF model constituted of piers (vertical elements), spandrels (horizontal elements) and rigid areas (nodes).

Fig. 1. Photo of the two case studies on the left and their representative 3D EF models on the right.

The piecewise-linear beam model (i.e. NLBEAM) was assumed to describe the IP nonlinear response of URM panels (Lagomarsino and Cattari (2013)) until very severe damage levels (DL, from 1 to 5), through the definition of a relation between the drift value and the corresponding fraction of the residual shear strength at the attainment of the i -th DL differentiated for piers or spandrels, flexural or shear behaviours. The case studies were modeled under the fixed based assumption. The interaction between adjacent SUs is modelled by elastic no-tension truss elements perpendicular to adjacent walls as well as fictitious floors (membrane elements) coupling only displacements parallel to the boundary walls. The sensitivity analysis on different connection types is well described in Angiolilli et al. (2021). Furthermore, to analyze the aggregate-effect, individual buildings were considered for each case study by neglecting the interlocking with the other structural units. In particular, for Catania’s aggregate, only the SU in the corner of the aggregate was considered, whereas for Visso’s aggregate, two SUs (i.e. SU1 and SU3) were analyzed (see Fig. 1). Table 2 and Table 3 summarize respectively the main geometrical information and the structural details of the investigated case studies. Note that the mass of the SU under isolated condition is slightly higher, as compared