PSI - Issue 78

Andrea Dhima et al. / Procedia Structural Integrity 78 (2026) 1366–1373

1372

failure in the Z-direction (Figure 5). Specifically, the uncorroded model and the one with a penetration X equal to 0.25 mm reach their capacity at 3.33 s. With a penetration depth of 0.5 mm, the failure instant occurs earlier, at 1.91 s, while for the two most severe scenarios ( X =0.75 mm and X =1 mm), failure occurs almost simultaneously, at 1.80 s and 1.79 s, respectively. Regarding the Y-direction, failure occurs only for the X =1mm scenario, at 5.54 s.

Uncorroded

X=0.25mm X=0.5mm X=0.75 mm X=1mm

4

-2 Acceleration [m/s 2 ] 0 2

-4

0

5

10

15

20

25

Times [s]

Fig. 5. Nonlinear dynamic analyses, input accelerogram with piers failure times in the longitudinal direction of the viaduct.

Assuming the brittle shear collapse is prevented by appropriate measures, the piers flexural capacity was investigated using the fibre model, replicating the same degradation scenarios. The moment-curvature diagrams shown in Figure 6 indicate that, even though the cross-section undergoes cracking of concrete and yielding of the reinforcement bars, its ultimate deformation capacity is not reached in any of the analysed scenarios.

Ry-My

12000

8000

4000

0

Uncorroded X=0.25mm X=0.5mm X=0.75mm X=1mm

-4000 My [kNm]

-8000

-12000

-0.0007 -0.0005 -0.0003 -0.0001 0.0001 0.0003 0.0005 0.0007

Ry [rad/m]

Fig. 6. Moment (My) - Rotation (Ry) diagram of pier P1.

5. Conclusions This study addressed the safety assessment of an existing bridge located in Basilicata region, framed within the regulatory context of the new Italian guidelines issued by the MIT for the management of infrastructure assets. The structural verifications required by the guidelines for the as-is condition were performed considering both traffic and seismic loading, initially focusing on the girder beams. While the seismic requirements are satisfied, the analysis of the undegraded state revealed that the 42-metre span beams do not meet the criteria for the performance level under traffic loading. The effects of reinforcement bar corrosion on the load-bearing capacity of the structural elements, commonly neglected by standard assessment procedures, were also investigated. The first analysis addressed the evolution of the beam capacity in three corrosion scenarios: (1) uniform degradation affecting only passive reinforcement; (2) non uniform degradation affecting both passive and prestressing reinforcement; and (3) actual degradation identified during the on-site inspection. This analysis under traffic loading demonstrated that reinforcement corrosion plays a decisive role, potentially reducing structural capacity by 30% to 40%, depending on the extent of the phenomenon. Additionally, the seismic vulnerability of the stocky piers was assessed through non linear analyses, identifying an inadequate shear capacity in the weaker (Z) direction, even in the uncorroded state. Evaluating scenarios with increasing corrosion penetration depth, it was concluded that degradation exacerbates this