PSI - Issue 78

Ataklti Gebrehiwet Gebrekidan et al. / Procedia Structural Integrity 78 (2026) 1665–1672

1671

Similar to the low hazard location, EI plays a critical role under high seismic hazard conditions, substantially affecting the ranking of the retrofit options. For example, within Comb 1, RC-J is ranked as the top retrofitting option again, however with a small difference to the second ranked FRP-C. In contrast, for Comb2, FRP-C emerges as the preferred choice. This shift in preference is largely due to FRP- ’s lower installation and maintenance costs and reduced environmental impact during installation and maintenance. Furthermore, unlike RC-J and S-J, both designed to maintain elastic behaviour under design-level seismic loads, FRP-C enhances pier ductility by enabling energy dissipation through controlled plastic deformation. As a result, the required FRP jacketing thickness is reduced, leading to lower installation costs, decreased environmental impact, and shorter construction time, thereby positioning FRP-C as a highly effective solution for bridges located in high seismic hazard regions. 6. Conclusions This paper explored the use of a multiple decision variables (DV), or criteria, to evaluate and rank seismic retrofitting strategies for a three-span reinforced concrete bridge. Four retrofit alternatives, designed under two seismic hazard levels, were considered, and multiple decision matrices were analysed, each incorporating different DVs that account for economic, social, environmental, and technical aspects to identify the retrofitting solution that best aligns with the objectives represented by the different criteria. From the application to the selected case study and under the described assumptions, the following conclusions can be drawn: • The inclusion of the Environmental Impact (EI) associated with post-event repair, installation, and maintenance activities significantly affected the preference for a retrofitting strategy over the remaining ones and altered the ranking of options in both seismic hazard levels. • When EI-related variables are excluded from the decision-making framework, Reinforced Concrete (RC) jacketing emerged as the top choice due to its low installation cost, despite relatively poor seismic performance for both seismic hazard levels. In contrast, deck seismic isolation ranked last due to high installation and maintenance costs. When EI was accounted for, the ranking and relative closeness to the ideal solution changed significantly. As a result, RC jacketing dropped in the ranking, while steel jacketing became the top choice for the low hazard site due to its low repair-related EIs. The Fibre-Reinforced Polymer (FRP) confinement ranking position was in turn favoured in the high hazard site due to its design focus on enhancing ductility, which results in advantages in cost and EIs. It is thus recognised that, while EI clearly influences the preference ranking, the relative importance of one alternative can overall vary depending on other underlying aspects, such as the use of different or more variables, the adopted weights, combination definitions and modelling assumptions. Further analyses and refinements will thus be directed to confirm the relative importance of each alternative, analysing their sensitivity to such aspects. Acknowledgements This study was developed in the framework of the projects FIRMITAS (Grant No. 2020P5572N, funded by the Italian Ministry of University and Research through the PRIN 2020 programme) and ReLUIS-DPC 2024-2026, WP13 (funded by the Italian Civil Protection Department). References Ingegneria e Verifiche, Roma, Italy. https://www.stradeanas.it/it/elenco-prezzi (accessed 3.17.25). Billah, A.H.M.M., Alam, M.S., 2014. Performance-based prioritisation for seismic retrofitting of reinforced concrete bridge bent. Structure and Infrastructure Engineering 10, 929 – 949. https://doi.org/10.1080/15732479.2013.772641 Briseghella, B., Borghese, V., Contiguglia, C.P., Pelle, A., Lavorato, D., Santini, S., Nuti, C., 2022. The greenway for bridge column rehabilitation: a comparison between different techniques based on multi-criteria decision analysis. Revista IBRACON de Estruturas e Materiais 15. https://doi.org/10.1590/S1983-41952022000600001 A.N.A.S. S.p.A., 2024. Price List | LISTINO PREZZI 2024, NC-MS.2024, Nuove Costruzioni – Manutenzione Straordinaria, Direzione