PSI - Issue 84

L. Fieno et al. / Procedia Structural Integrity 84 (2026) 1136–1143

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Fig. 3. Closure joint before local inspection opening (left) and after local inspection opening (right

The case under examination clearly highlights the importance of routine inspections as a preliminary phase to special inspections, of the correct interpretation of their outcomes, and of the available photographic documentation. It also demonstrates the fundamental role of subsequent special inspections in the in-depth investigation of specific deterioration phenomena that require direct and targeted verification, as in the present case. 4.3. Case Study 3 – Deck Arch Bridge The structure consists of three distinct portions separated by joints: two lateral sections (one with three spans and one with seven spans) and a central upper-deck reinforced concrete arch. The deck is configured as a grillage composed of longitudinal beams and transverse members. The piers consist of four shafts with a T-shaped cross-section. Following visual inspection, transverse and diagonal cracking was detected on the pier shafts in a poorly accessible and not fully visible area. As a result of this finding, the inspection was extended to other portions of the shafts that were even less visible, some of which were covered by vegetation and therefore not observable during a standard routine inspection. In these areas, the same types of cracking were identified, confirming the widespread nature of the phenomenon on the shafts of the pier under consideration.

Fig. 4. One of the cracks detected on the pier shafts

The findings clearly emphasize the importance of thorough knowledge of the structural typology and boundary conditions, as well as the accuracy and level of attention that the inspector must apply to all elements of the structure, without neglecting even those portions that appear marginal or are difficult to access. Indeed, limited and poorly visible areas may conceal significant structural deficiencies. The structural defects identified made specific safety interventions on the structure necessary. 4.4. Case study 4 – Steel trestle bridge with composite deck and prestressed concrete slab The structure being assessed is a steel trestle bridge, with a deck consisting of two main steel longitudinal girders. The structural system is composite (steel– concrete) in the side portions, where the prestressed reinforced‑concrete slab acts compositely with the steel girders, while in the central portion the deck is a steel orthotropic deck.