PSI - Issue 62

Marco Menegotto et al. / Procedia Structural Integrity 62 (2024) 1014–1019 Menegotto, M.,. Fieno, L., Rocchi, M.C.

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Actions are divided into so-called ordinary maintenance, i.e., repairs aimed at restoring the conservation of elements, and extraordinary maintenance, aimed at strengthening or upgrading them; in certain cases, it is convenient to replace them, as suggested also by High Council of Public Works (CSLLPP), in the Report to the Parliament on the National Recovery and Resilience Plan (PNRR). 3. Frequent defects The monitoring inspections have pointed out typical defects, related to the severe climate conditions and to poor detailing: surface degradation, due to aging or to poor rainwater drainage systems, particularly at the joints between spans (fig. 3), with consequent (i) direct erosion of concrete cover and more, leading to reduction of the cross section and corrosion of the reinforcement, as well as (ii) leaking water along the exposed surfaces of decks and piers, leading to spalling phenomena after cycles of freezing and thawing.

Fig. 3. Water leak

Damage level :

a)

b)

c)

Figure 3 shows examples of such defects: origin of leakage; conventional level of damage for the assumptions in numerical verifications: a) minor, full concrete cross-section and 10% reduction of peripheral reinforcement; b) medium, 50 mm concrete depth neglected and 50% reduction of peripheral reinforcement; c) severe,100 mm concrete depth neglected and peripheral reinforcement neglected. As an example, graphs in fig. 4 depict the number of viaducts with surface - of Piers and Decks, respectively - affected by severe damage on given percent of the total element’s surface. It clearly appears that the great majority of cases affected have a very small part (< 5%) of their surface damaged (generally along the path of leaking water).

Fig. 4. Number of Viaducts (Piers / Decks) severely damaged vs. given percents of their surface