PSI - Issue 84

Federica Di Criscio et al. / Procedia Structural Integrity 84 (2026) 1023–1030

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The effects of the corroded section’s location on the structural safety index over time are evident, as shown in Fig. 6(a). The curve corresponding to corrosion localized at the base of the pier begins to degrade at an earlier stage; yet it exhibits a more gradual reduction in seismic safety over time. Conversely, when corrosion is located higher along the pier, the safety index starts to deteriorate later but declines more abruptly. For the simply supported girder, the analysis is focused on the midspan section, where the bending moment demand is maximised. The time-dependent evolution of the structural safety is assessed by comparing the degraded flexural capacities with the moment demand at this critical section. The resulting trend for the girder is shown in Fig. 6(b). As expected, a progressive reduction in safety over time due to corrosion is observed. For the girder, risk mitigation strategies are further assessed by imposing operational restrictions, including limiting traffic to 44-ton vehicles or implementing the closure of a single lane. The results demonstrate the capability of the proposed framework to quantify the impact of such interventions on structural performance over time.

(a)

(b)

Fig. 6. Time-dependent safety index for: (a) the pier under different corrosion locations; and (b) the girder, including operational restrictions.

Finally, the time-dependent safety curves can be presented in a single graph, enabling comparative assessment and a more effective prioritization of interventions among bridge elements. Fig. 7(a) illustrates the curves for the girder with the applied operational limits, alongside the curve for the pier. In this specific application, it is worth noting that the prestressed girder is expected to reach the safety threshold before the pier. Moreover, the results suggest that a 44-ton traffic limit synchronizes the degradation of the girder and the pier, causing both elements to reach the safety threshold almost concurrently. Alternatively, adopting a stricter operational limit on the deck can delay intervention on the girder while anticipating it on the pier, allowing for a more gradual and targeted maintenance strategy. Finally, to account for variability due to the corroded section’s location, the pier’s safety curve can also be represented as a tolerance range, between upper bound and lower bound, as shown in Fig. 7(b).

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(b)

Fig. 7. Global comparison of bridge safety considering: (a) a single corrosion scenario for the pier; and (b) a tolerance range accounting for possible uncertainties in the corrosion location.