PSI - Issue 44

Fabrizio Paolacci et al. / Procedia Structural Integrity 44 (2023) 307–314 Fabrizio Paolacci et al. / Structural Integrity Procedia 00 (2022) 000–000

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(a) (b) Figure 3: a) capacity curves in x and z direction, b) drift along the height for = 2475 years

The fragility curves, illustrated in Figure 4a, have been derived by interpolating the results with the Maximum Likelihood technique, as suggested by Baker (2015). In this respect the mean PGA of the record set A and B has been used as hazard parameter . According to the proposed method, this choice does not affect the risk assessment and it is only necessary for the representation of the curves only.

(a) (b) Figure 4: a) fragility curves for set a and set b, b) return period for several LS

By using the fragility functions of Figure 4a, it has been possible to derive the mean annual frequency of exceeding the DL, SD and NC limit states, that is the corresponding return period . These latter are shown in Figure 4b. The outcomes clearly show a substantial similarity of results coming for the two sets of natural records. The return period related to damage limitation (DS) varies from 420 to 480 years, whereas the ultimate condition (NC) corresponds to a return period variable from 1879 to 2148 years. Significant damage corresponds to a equal to 955 and 850 for set A and B, respectively. The biggest difference corresponding to the NC condition is mainly related to the large sensitivity of this limit state to the response level. Moreover, the invariance with time of the axial force in the columns used in the derivation of the limit states, could have a certain influence on the limit states and thus on the risk. In any case, it is worthy to note that the nonlinear analyses have been fully three-dimensional and the selection of the natural records has been performed without any definition and related scaling operation, differently from the most popular seismic risk analysis methods, demonstrating the high stability of the new risk framework assessment procedure.