PSI - Issue 64

Rosario Montuori et al. / Procedia Structural Integrity 64 (2024) 841–848 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

845

5

Mode 1

Mode 2

Mode 3

(a)

(b) Fig. 6. Structural model implemented in SAP 2000 (a); The first three modal shapes of the structure (b)

3.2. Evaluation of the reliability index According to the Section 8.3 of the current Italian provisions, the seismic reliability indices ( ) have been obtained as: = PGA C . LS PGA D . LS (1) where PGA C . LS and PGA D . LS are, respectively, the value of the peak ground acceleration corresponding to the achievement of a specific limit state (Capacity) and the value of PGA for the specific limit state (Demand). The numerical results have been obtained by using the post-processor VIS15 combined with the plugin SPF (Seismic Performance Finder). The index has been evaluated for the Operational Limit State (SLO), Damage Limit State (SLD) and Life Safety Limit State (SLV). The maximum inter-storey drift (D) is used as main parameter for the evaluation of the reliability index for SLO. While, in the case of the SLD and SLV limit states, the performance indices have been computed by considering the ultimate resistance of the RC cores. In particular, two failure mechanism have been considered: the shear failure of the concrete walls (SF_w) and the combined bending compression actions of the cores (FF). A summary of the numerical results is provided in Table 3. It is immediate to recognize that the shear failure mode of the concrete RC cores is dominant compared to other crisis mechanisms. Consequently, the seismic vulnerability index is equal to 9.00 %. Regarding the structural verification of the steel members, it is important to underline that several numerical analyses have been carried out both for gravity loads and in seismic conditions, but there are almost no structural criticalities. The results are not shown for the sake of summary, but more details are presented in Pisapia et al. 2023.

Capacity [%]

Table 3. Vulnerability indices for each Limit State

Demand a g [g] a g [g] 0.065 0.130

Limit State

Criterion

SLO

D

200 163

FF

0.085 0.085 0.210 0.210

0.139 0.022 0.118 0.019

SLD

SF_w

26 56

FF

SLV

SF_w

9