PSI - Issue 84

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

1205

Since 2015, the Tevere Viaduct, located on S.S. 675 “Umbro-Laziale, has been subjected to several diagnostic investigations aimed at determining the geometric and mechanical properties of structural elements, at mapping the overall defect pattern of the structure, and at assessing the condition of the prestressing tendons. Visual inspections revealed two main indicative defects: evident moisture stains near the prestressing tendons and a widespread flexural cracking pattern along the deck girders. The former highlights deficiencies in waterproofing and a not effective filling of tendon ducts while the latter is mainly attributable to a deficit in residual post-tensioning force. Endoscopic inspections confirmed highly heterogeneous conditions of the prestressing tendons, including incomplete grouting and, in some cases, early-stage pitting corrosion. Residual prestressing stresses were evaluated through strand detensioning tests, revealing a significant variability and, locally, substantial prestress losses. Although no immediate safety-critical conditions were identified at a local level within the prestressing system, the observed loss of prestressing led to section decompression and a marked reduction in the global flexural and torsional stiffness of the structure. The results of the investigation were used to define a FE model for the design and interpretation of a static load test. The load test, adopted as a diagnostic technique, highlighted specific features of the bridge’s behavior. In particular, as the load level increased, variations in both flexural and torsional stiffness were observed, attributable to progressive section decompression and crack opening along the deck girders. Several simulations were performed to reproduce the experimental behavior of the load test, initially by introducing predefined reductions in the material’s elastic modulus within a single model, and subsequently by refining the modeling through an appropriate combination of stiffness reductions for various load levels. This integrated modeling approach yielded numerical results that are in good agreement with the experimental behavior. By correlating these results with an analysis of the section at its different behavioral stages, useful insights were obtained regarding the structural performance of the bridge. These findings can be effectively leveraged for the assessment of structures with similar characteristics and degradation conditions, as well as to support decision-making processes related to the management, load regulation, and safe operation of existing prestressed concrete bridges. 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