PSI - Issue 62

5

Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Andrea Nettis et al. / Procedia Structural Integrity 62 (2024) 693–700

697

2.2. Modelling and seismic actions The numerical model of the bridge is defined by using SAP2000 software package following the strategy shown in Fig. 3. In detail, all the piers are modelled as elastic frame elements fixed at the base, while abutments are simulated as fixed supports. The superstructure is modelled as a single frame element connected to the substructure components through a set of two-node links simulating the elastomeric bearings. This assumption strongly reduces modelling efforts in seismic analysis where the continuous superstructure is considered to respond without damage and to distribute the seismic mass and inertia forces on the substructure components. Structural and non-structural loads are assigned to the superstructure. Considering the elastomeric bearings, LDRB are modelled as linear links equipped with a 2% equivalent viscous damping. Conversely, HDRB and LRB are represented by multilinear-plastic links whose cyclic and hysteretic behaviour is presented in Errore. L'origine riferimento non è stata trovata. (Maghsoudi-Barmi et al., 2021). A kinematic hysteretic behaviour is assigned in this case. Nonlinear modelling parameters of the bearing devices are reported in Table 1. The landslide-induced transverse displacements related to the given settlement scenario are assigned to the base node of substructure components in the transverse direction. Note that the interaction between the landslide and foundations is not considered in this study and a fixed support at the base of the substructure components is considered.

Fig. 3. Modelling strategy and hysteretic relationships of the elastomeric bearings.

A target spectrum for the site of interest is extracted considering an expected peak ground acceleration (PGA) equal to 0.40g. A dataset of 20 scaled natural records is first extracted by using the tool REXEL (Iervolino et al., 2010). Spectrum-compatibility was checked with respect to the target spectrum and by using the Eurocode 8 (CEN, 2005). The period of interest is fixed between 1.00 and 2.50 s considering that high-frequency modes are of minor importance for the analysed case studies whose main modal periods are higher than 1.50 s. Subsequently, this record dataset is further scaled to achieve a PGA of the target spectrum equal to 0.30g and 0.20g. In this way, a total number of 60 ground-motion records is obtained.

Table 1. Modelling parameters of the elastomeric bearings.

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[ / ] [ / ] [ ] 2020 - -

Δ ( =150%) 220 mm

Type

LDRB HDRB

13889 23333

839

69 70

276 340

170 mm 150 mm

LRB

1140