PSI - Issue 62

Andrea Nettis et al. / Procedia Structural Integrity 62 (2024) 693–700 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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50% probability of exceedance decreases to 0.76 g. Scenario S4 is the most critical for all the case-study bridges, as demonstrated in Fig. 2. The most relevant increase in fragility is observed for LRB where a reduction of the PGA associated with ( | ) equal to 50% reaches 0.75g which is equal to a reduction of 75% with respect to the scenario S0. The variation in fragility associated with HDRB and LDRB, measured as the difference between the PGA at ( | ) equal to 50% for S4 with respect to S0, is equal to -64% and -51%, respectively.

Fig. 4. Fragility curves related to the case-study bridges equipped with a) LDRB; b) HDRB; c) LRB.

4. Conclusions This paper presents a study on the seismic fragility of continuous-deck bridges isolated through elastomeric bearings subjected to landslide-induced ground settlements. In such bridge typology, the relative differential displacements of substructure components involve significant strain for the bearings reducing their residual deformation capacity and determining the increase of bridge fragility. This study reports a parametric analysis in which the seismic fragility of a given case-study bridge is discussed based on variable settlement scenarios and the typology of elastomeric bearings (low-damping rubber bearings, high-damping rubber bearings and lead-rubber bearings). Four settlement scenarios are analysed based on variations of the transverse displacement of substructure components. Seismic fragility curves considering specific settlement scenarios are computed and compared to the un-deformed condition. Results show that the bridge fragility increases for settlement scenarios inducing localized displacement of substructure components. In addition, the influence in fragility increases for high-damping nonlinear response, with respect to a low-damping pseudo-elastic response. The achieved results can be considered preliminary outcomes on the effect of low-moving landslides on the seismic fragility of isolated bridges. Further developments should be oriented to the investigation of the consideration of modelling uncertainties on the bearing devices, variable-intensity settlement scenarios and bridge geometric characteristics. Acknowledgements All authors thank the consortium FABRE for the financial support. The third author acknowledges funding by Italian Ministry of University and Research, within the project ‘PON -Ricerca e Innovazione 2014 – 2020, (D.M. 10/08/2021, n. 1062) CUP CODE: D95F21002140006. The last author acknowledges funding by Centro Nazionale Sustainable Mobility Center, within the framework of “MOST” project, CUP code: D93C22000410001.