PSI - Issue 64

Amedeo Caprino et al. / Procedia Structural Integrity 64 (2024) 2149–2156 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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In addition, starting from January 2022 there is an increase of the frequencies, especially in mode1 and 7. This is due to the change in loading conditions of the structure coinciding with the early stages of repair work a b

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Fig. 6. (a) Variation of the natural frequencies of the bridge as a function of time in the observation period. (b) Variation of the natural frequencies of the bridge as a function of temperature in the observation period. Time trend of the single structural mode for (c) mode 1 and (d) mode 7. 4. Retrofit strategy and intervention Taking into account the surveys carried out on the structure and the data provided by the monitoring system during the observation period, it was possible to design a series of repair and rehabilitation works. The design process took quite a long time, considering the many different actors involved, and was completed at the end of 2020. The project will maintain two traffic lanes, one in each direction, and provide bike lanes in the roadway. The static and seismic upgrading of the bridge includes work: • Reinforcement of those elements that are excessively undersized for the current road loads required by the technical standards. • Replacement of the deck support systems for the purpose of seismic adaptation. • Insertion of new seismic dissipators to the back of the abutments in order to dampen the seismic action of the deck, in the longitudinal direction, which is transferred to an external contrast system composed of piles and geotechnical tie-rods.