PSI - Issue 78

Allegretti M. et al. / Procedia Structural Integrity 78 (2026) 852–858

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Fig. 5. ADSR performance points (a) long. (b) trasv.

The results show that in the longitudinal direction, as the model accuracy increases, the sti ff ness of the equivalent SDOF system’s curve also increases, leading to higher values of the safety factor. In this regard, the intervention represented in the LV2 model is e ff ective, since the safety factor, according to the current Italian national standards Ministero delle Infrastrutture e della Mobilita` Sostenibili (2022) , meets the requirements for the structural upgrade. In the transverse direction, increasing the level of knowledge results in a marked sti ff ness di ff erence between the initial model and the one refined by in-situ testing, accompanied by a reduction in the maximum displacement. The contribution of the slab reduces the system’s sti ff ness, allowing for larger displacements.

Table 3. Safety factors of the analysis.

Models SF ζ Y Model LV0 0.53 0.57 Model LV1 0.65 0.72 Model LV2 0.87 0.80 SF ζ X

5. Conclusion

This study provided an in-depth analysis of the seismic vulnerability of the historic masonry bridge, conducted in accordance with Italian regulations, highlighting how the level of knoledge significantly influences the structural re sponse. Starting from an initial, highly conservative model (LV0), progressively refined through in-situ investigations (LV1) and the consideration of the contribution of the reinforced concrete slab (LV2), several key findings emerged: • Increasing the level of detail leads to a more reliable and less conservative assessment of structural performance, substantially reducing uncertainties in seismic response and enabling the full exploitation of the structure’s load bearing capacity; • The LV1 model, enriched with experimental data, revealed a significantly higher global sti ff ness compared to the initial assumptions, with safety factors markedly greater than those obtained with the LV0 model; • The inclusion in the model of the reinforced concrete slab (LV2) demonstrated a decisive impact on modal behavior, improving the overall structural integrity in the longitudinal direction and ensuring compliance with national seismic provisions.