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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Fig. 2. Pushover curves of the case studies in Catania and Visso.

2.3. Fragility curves NDAs were performed by adopting sets of accelerograms (bedrock condition) with increasing seismic intensities. Local mechanisms were evaluated separately (see Simoes et al. (2014)) but based on the storey accelerations derived from the NDAs performed on the 3D global model. That allows to implicitly consider the filtering effect provided by the nonlinear dynamic response of the structure (see Angiolilli et al. (2021), Lagomarsino et al. (2022)). The NDAs allowed for the evaluation of the structural capacity in terms of fragility curves associated with the IP behavior as well as the IP combined with local mechanisms. Among several procedures available in the current literature for characterizing the relationship between engineering demand parameter (EDP) and intensity measure (IM, namely the spectral acceleration associated to the period of the structure - Sa(T1) - or the peak ground acceleration - PGA), for the Catania’s case, the m ulti-stripes approach was adopted, by using twenty sets of accelerograms spectrum compatible with ten increasing values of Sa(T1). Furthermore, the derivation of the fragility curves, expressed as a function of Sa(T1) and in terms of two performance conditions (Usability Preventing Damage – UPD – or Global Collapse – GC), were performed by the maximum likelihood method (see Angiolilli et al. (2021), Iervolino (2017)). On the other hand, for the Visso’s case, the Cloud Method (e.g. Angiolilli et al. 2022a, Jalayer 2017) was adopted - so that at each of 320 records represents a single IM value corresponding to a single EDP response. The IM adopted for that case study is the PGA. Although the IM and the method used are different, the results are comparable to assess the overall impact on the fragility curves.