PSI - Issue 62

Rossella Venezia et al. / Procedia Structural Integrity 62 (2024) 796–808 Rossella Venezia and Alessio Lupoi / Structural Integrity Procedia 00 (2019) 000 – 000

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In each of the five pushover analyses with modal shape in direction “+” load distribution, the first limit condition is reached in the plastic hinge at the bottom of no. 12 pier, because the demand chord rotation exceeds the capacity one. W hile in the analysis with modal shape in direction “ - ” load distribution, it is reached in the plastic hinge at the bottom of no. 10 pier for capacity chord rotation achievement. 4.3. Structural performance evaluation Since the displacements at the top of different piers have been monitored, different stiffnesses of the equivalent SDOF model have been obtained, resulting in different dynamic properties and, consequently, different responses of the structure (Isaković and Fischinger 200 ) . Thus, for every load distribution, each of the five pushover curves has been transformed to capacity curves by the related constant Γ . As required by the N2 procedure, every capacity curve has been approximated to a simplified elastic-perfectly plastic curve to get the inelastic displacement demand through demand spectra. In the last step, the inelastic displacement demand for the SDOF model has been transformed, by the previous constant Γ , into the displacement demand of the MDOF system. Hence, expected global performance has been assessed by comparing each displacement demand, i.e. the target displacement, with every displacement capacity. The results in terms of C/D ratios, for every load distribution, are presented in the see Table 5, Table 6, Table 7, and Table 8. Table 5. Influence of reference point on performance evaluation via the N2 method: uniform shapes in direction “+” . Load distribution Displacement capacity [ m ] Displacement demand [ m ] C/D ratio Uniform shape X (+)_P1 0.08 0.19 0.41 Uniform shape X (+)_P2 0.10 0.23 0.45 Uniform shape X (+)_P6 0.15 0.26 0.60 Uniform shape X (+)_P10 0.11 0.20 0.54 Uniform shape X (+)_P14 0.06 0.18 0.36

Table 6 . Influence of reference point on performance evaluation via the 2 method: uniform shapes in direction “ - ”. Load distribution Displacement capacity [ m ] Displacement demand [ m ] C/D ratio Uniform shape X (-)_P1 0.09 0.21 0.42 Uniform shape X (-)_P2 0.12 0.25 0.47 Uniform shape X (-)_P6 0.12 0.25 0.51 Uniform shape X (-)_P10 0.09 0.21 0.46 Uniform shape X (-)_P14 0.04 0.15 0.25 Table 7. Influence of reference point on performance evaluation via the 2 method: uniform shapes in direction “+”. Load distribution Displacement capacity [ m ] Displacement demand [ m ] C/D ratio Modal shape X (+)_P1 0.16 0.22 0.72 Modal shape X (+)_P2 0.12 0.21 0.56 Modal shape X (+)_P6 0.09 0.23 0.41 Modal shape X (+)_P10 0.10 0.20 0.50 Modal shape X (+)_P14 0.08 0.19 0.40 Table 8. Influence of reference point on performance evaluation via the N2 method: uniform shapes in x direction “+”. Load distribution Displacement capacity [ m ] Displacement demand [ m ] C/D ratio Modal shape X (-)_P1 0.08 0.20 0.37 Modal shape X (-)_P2 0.09 0.23 0.40