PSI - Issue 84

Diego Esposito et al. / Procedia Structural Integrity 84 (2026) 1198–1205

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actions are particularly important within the management process of existing bridges and in planning interventions to ensure safety and extend the service life of infrastructures. In this context, prestressed reinforced concrete bridges represent critical elements of the road network, Scalbi et al. (2023), as they were designed and built during a period when the designs didn’t consider durability as a main requirement. Consequently, they exhibit high sensitivity to degradation phenomena caused by both atmospheric agents and traffic loads, Petrangeli et al. (2022). Within this category of structures, the main attention is focused on the bridges with post-tensioned prestressing tendons, where degradation phenomena are not directly detectable through visual inspections. Therefore, advanced diagnostic and monitoring activities are indispensable to obtain reliable structural assessment of current safety levels. This paper presents a combined diagnostic methodology and the subsequent numerical modeling phase, applied to the case study of the Tevere viaduct located on the S.S. 675 “Umbro-Laziale”, characterized by post-tensioned prestressing tendons and significant degradation phenomena likely correlated to heavy traffic loads, Agredo Chavez et al. (2022). The methodology first involved a diagnostic investigation campaign, which enabled an initial calibration of the bridge’s numerical model and the load test design. Then, the load test’s results highlighted unexpected features and provided useful insights to improve the accuracy of numerical modeling.

Nomenclature FEM

Finite element model Ground-penetrating radar Polytetrafluoroethylene

GPR PTFE

2. The Tevere viaduct The Tevere Viaduct is located at km 33+110 along State Road 675 “Umbro-Laziale,” near the municipality of Orte (VT), Italy. Integrated into the Civitavecchia–Viterbo–Orte–Terni–Rieti road system, the viaduct was built between 1980 and 1985 as part of the Viterbo–Orte section and is currently under concession to ANAS S.p.A. The viaduct has an overall length of 1,353 m. It is characterized by two separate carriageways, each comprising 33 spans, for a total of 66 deck segments (Figure 1). Each carriageway is made up of simply supported spans of 41 m length (39.75 m net span). The gross width of each deck is 9.50 m (Figure 2). The deck is composed of two precast prestressed reinforced concrete box girders, simply supported. Prestressing is achieved through six post-tensioned tendons, three for each web of the box girder: four anchored at the ends of beam and two in the slab. Transverse load distribution between the two box girders is ensured by two prestressed reinforced concrete end diaphragms. The slab is completed on site through a wet joint, which ensures structural continuity between the two box sections. The substructure elements are made of ordinary reinforced concrete and include, for each carriageway, 32 piers and two abutments, all of which are founded on deep pile foundations. The piers have a hollow single-cell cross-section and variable heights, reaching up to 40 m. Finally, each box girder is equipped with a hemispherical steel and PTFE bearing, allowing for the accommodation of rotations and longitudinal displacements.

Figure 1. Panoramic view of the Viaduct.