GNGTS 2022 - Atti del 40° Convegno Nazionale

256 GNGTS 2022 Sessione 2.2 Fig. 1 - a) Structural scheme of the industrial building casa study; b) Fragility curve for X-CBF of the industrial building with PGA as IM: case with North-South seismic component (N) applied in longitudinal direction (Y), for both main- shocks (MS) and seismic sequences (SS) and for the three limit states (DL: limitate damage; SD: severe damage; NC: near collapse). a) b) considered and compared with the 40 main events. Then, fragility curves have been built, with the aim to evaluate the seismic vulnerability. As known, a fragility curve defines the probability of exceeding a certain level of damage (a limit state) with a parameter that indicates the seismic intensity (IM-Intensity Measure). In this work the “Cloud Analysis” method (Han et al. , 2015; Hosseinpour and Abdelnaby, 2017; Jalayer et al. , 2015; Porter, 2021) has been used, by considering PGA or Sa as IM, and the drift as “Engineering Demand Parameter” (EDP). Drift limit values given in (Applied Technology Council et al. , 1997) are considered, according to damage (DL), severe damage (SD) and near collapse (NC) limit states. Globally, 160 nonlinear dynamic analyses have been performed, considering the two different combinations of seismic action directions. Fragility curves have been built by distinguishing the response of the moment resisting portal frames from the X-CBFs one. The final results have shown that fragility curves due to seismic sequences are generally on the left compared to those of the single main events, therefore indicating a damage accumulation due to the succession of events. However, the increase of the probability of exceedance is quite limited and around a maximum value of 6% for the near-collapse limit