PSI - Issue 84

Anna Bontempi et al. / Procedia Structural Integrity 84 (2026) 1039–1046

1046

The two curves (Figure 9b) exhibit a reasonably similar trend, with nearly the same slope in the cracked stage. The experimental curve shows a little steeper initial response and reaches higher moments at low curvature, indicating greater early stiffness/strength than predicted. Overall, the analytical model is more gradual and tends to underestimate the moment for a given curvature over most of the loading path. Near the ultimate range, both curves capture a peak followed by degradation, but the analytical prediction exhibits a more abrupt post-peak drop. The resisting bending moment obtained from the analytical calculation is also in good agreement with the experimental result, with values of 1178 kNm and 1227 kNm, respectively. 5. Conclusions The main conclusions of the experimental investigation are summarized as follows: • the applied strengthening system exhibited satisfactory performance in terms of ultimate resistance, leading to an increase in ultimate load of approximately 33% compared to the unstrengthened beam; • despite the use of an elastic–brittle strengthening material such as CFRP, the structural element was able to develop a good level of ductility, with a displacement-based ductility of about 6; • the test represents one of the few examples reported in the literature in which strengthening was applied to a full-scale beam that had been subjected to natural degradation for more than 90 years; • the materials used are corrosion-inert and help improve the durability of the existing cross-section, which had already been significantly compromised; • the analytical calculation is able to reproduce with good accuracy the ultimate moment and curvature values observed in the experimental test and can therefore be adopted as a predictive tool for the structural behavior of strengthened beams. References [1] Belletti, Beatrice, Jesús Rodríguez, Carmen Andrade, Lorenzo Franceschini, Javier Sánchez Montero, and Francesca Vecchi. 2020. ‘Experimental Tests on Shear Capacity of Naturally Corroded Prestressed Beams’. Structural Concrete 21 (5): 1777–93. https://doi.org/10.1002/suco.202000205. [2] Di Prisco, Marco. 2019. Critical infrastructures in italy: state of the art, case studies, rational approaches to select the intervention priorities. fib Symposium Proceedings, Fédération Internationale du Béton (fib). [3] Di Stefano, Nico. 2022. ‘Assessment of Existing Bridges with Special Emphasis on Corrosion’, PhD Thesis of the University of Brescia, curriculum “Rehabilitation of historical and modern buildings”. [4] Recupero, Antonino, and Nino Spinella. 2019. ‘Experimental Tests on Corroded Prestressed Concrete Beams Subjected to Transverse Load’. Structural Concrete 20 (6): 2220–29. https://doi.org/10.1002/suco.201900242. [5] Rogers, Rhys A., Liam Wotherspoon, Allan Scott, and Jason M. Ingham. 2012. ‘Residual Strength Assessment and Destructive Testing of Decommissioned Concrete Bridge Beams with Corroded Pretensioned Reinforcement’. PCI Journal 57 (3): 100–118. https://doi.org/10.15554/pcij.06012012.100.118. [6] Savino, Pierclaudio, Francesco Tondolo, Donato Sabia, et al. 2023. ‘Large-Scale Experimental Static Testing on 50-Year-Old Prestressed Concrete Bridge Girders’. Applied Sciences 13 (2): 834. https://doi.org/10.3390/app13020834. [7] Walraven, Joost. 2021. Assessment of Concrete Structures with Corroded Reinforcement: Development of Recommendations. Proceedings of the 3rd CACRCS Workshop – Capacity Assessment of Corroded Reinforced Concrete Structures , Delft University of Technology.