PSI - Issue 78

Franco Braga et al. / Procedia Structural Integrity 78 (2026) 2184–2191

2189

4.2. Materials In the 2009 calculation report f or the intervention, the masonry was described as consisting of “squared sandstone blocks bonded with cement mortar and horizontal brick courses.” During an inspection of the building remains on February 10, 2020, this description was confirmed; remains of reinforced concrete – hollow block floors and reinforced concrete floor beams were also observed. Based on these findings, the building modeling was carried out considering the following mechanical properties of the masonry (derived from Table C8A.2.1 of the “ Circolare del Min. Infrastrutture e trasporti, esplicativa delle NTC08 ”, n.617/ 2009).

Masonry type

f m ( N/cm Min-max

2 )

 0 ( N/cm Min-max

2 )

E ( N/mm 2 ) Min-max

G( N/mm 2 ) Min-max

w (kN/m 3 )

260 380

5.6 7.4

1500 1980

500 600

21

Masonry made of split stones with good texture

Fig. 7. Excerpt from Table C8A.2.1 of the “C ircolare n.617/2009 ”

Assigning a medium level of knowledge (LC2) to the present analysis, the mean values of the ranges reported in Table C8A.2.1 were considered for both strengths and stiffnesses, as follows: f m = 32 kg/cm 2  0 =0.65 kg/cm 2  = 21 kN/m 3 The stiffness were reduced by 50% to account for the aging of the structure. The confidence factor used was FC = 1.2, while γ M was assumed equal to 2 (for seismic checks). 4.3. Load analysis The following vertical loads were considered for the structural analysis:

Description

Load(kN/m 2 )

G1 = Self weight of r.c.-hollow block slabs

2.3 2.7 2.0

G2 = Permanent loads

Q = Live loads

5. Analysis results 5.1. Dynamic behavior of structures

The modal dynamic analysis highlights a first mode of vibration with a period of 0.404 s, which mobilizes 64% of the mass in the Y direction, essentially coinciding with the N-S direction, and a second mode of vibration with a period of 0.376 s, which mobilizes 60% of the mass in the X direction, essentially coinciding with the E-W direction.

First vibration mode of the structure – T=0.4 sec Mobilizes 76% of the seismic mass in the Y direction (E-W direction)

Third vibration mode of the structure – T=0.38 sec Mobilizes 73% of the seismic mass in the X direction (N-S direction)

Fig. 8. Primary vibration modes