PSI - Issue 62

R. Martini et al. / Procedia Structural Integrity 62 (2024) 392–399

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Martini R. et al. / Structural Integrity Procedia 00 (2019) 000 – 000

7. Conclusions The paper dealt with the investigation of two paired pre-stressed 3-cell box-girder concrete bridges performed in the last 2 years and following the framework proposed by the new Italian Guidelines 2022 for the risk assessment of existing bridges. The overall bridge health status was already known to the Administrator, who decided for the structure demolition and reconstruction, also in view of the outcomes of the safety assessment of the structure according to the Italian code. Anyway, after the visual inspection, one of them was closed to traffic due to significant age-related degradation phenomena such as the deterioration of the half-joints and noticeable defects in the integrity of the prestressing cables (e.g., moisture traces coming from inside the beam in correspondence of cables), while the other remained operative to support the entire traffic of the route. Furthermore, both bridges showed a significant permanent deflection of the longest span that causes depressions in the road pavement. Additionally, on one bridge, cracks inclined at approximately 45° were observed on the external face of the box-girder in correspondence of the half-joint, consistent with a damage mechanism due to shear forces that may be an indication of loss of pre-stressing. From March 2022 several experimental campaigns and monitoring actions were performed by the FABRE Consortium and ANAS in the framework of the research agreement signed by the parties, in order to improve their reciprocal knowledge on the behaviour of pre-stressed concrete bridges and to control the bridge still open to traffic. Finally, some experimental campaigns have been scheduled for the near future, before the demolition of the bridges, in order to study the usefulness of non-destructive testing for the investigation of the pre-stressing system, to evaluate the effectiveness of dynamic monitoring systems in capture damage on pre-stressed cables, and to characterise the behaviour of half-joints up to collapse operating on a real scale bridge. Acknowledgements Authors belonging to the Università Politecnica delle Marche and the University of Camerino are grateful to Engg. Andrea Torsani, Carmine Cacchione and Marco Mancina for their professionalism, respect for roles, and spirit of cooperation aimed at a mutual knowledge enhancement. References ANSFISA. Operative Instructions for the application of the Guidelines on risk classification and management, safety assessment and monitoring of existing bridges (Guidelines 2022). In Italian language. 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