## 6 Conclusions  
This paper presents a comprehensive methodology for selecting seismic retrofitting solutions for reinforced concrete beams with shear deficiencies. Five retrofit alternatives designed to improve the shear capacity in the expected plastic hinge formation zone were evaluated to ensure compliance with current seismic regulations. A service life of 50 years was considered for each alternative, with preventive maintenance adapted to the specific properties of the material. The retrofit alternatives evaluated include concrete jacket (CJ), shotcrete jacket (SCJ), steel jacket with structural epoxy adhesive (STE), steel jacket with mechanical anchors (STA), and incorporation of carbon fiber reinforced polymer (CFRP). A hierarchical decision-making model encompassed four dimensions-functionality, economic, environmental, and social- and was analyzed through eight criteria and measured by 16 specific indicators. The BWM method was applied to weigh the criteria and rank the reinforcement alternatives. At the same time, four new MCDM methods were used for the final ranking: EDAS, MABAC, CODAS, and MARCOS. Life cycle assessments of the economic, environmental, and social dimensions were conducted using a \"cradle to grave\" approach. The SCJ and STE alternatives demonstrate cost reductions compared to the traditional CJ option. The STE, STA, and CFRP alternatives offer substantial environmental and social advantages over the concrete-based CJ and SCJ alternatives. Compared to the CJ alternative, the STA alternative achieves the most significant reductions in environmental and social impacts, with decreases of 76% and 73%, respectively. STE shows reductions of 61% and 59%, while CFRP achieves reductions of 58% and 66%, respectively, in environmental and social impacts. In addition, STE and CFRP show the shortest execution times and lowest architectural impacts among the alternatives evaluated. Based on the assumptions of this study, the CFRP and STE alternatives emerge as the preferred options when economic, environmental, social, and functional criteria are considered together. Retrofitting with carbon fiber significantly reduces environmental and social impacts while enhancing functionality despite the high costs associated with the raw materials. Steel jacketing with structural epoxy adhesive is also viable, providing balanced performance across all criteria and outperforming the alternative incorporating structural steel with mechanical anchors. In contrast, alternatives involving concrete are the least favorable due to their high environmental and social impacts coupled with lower functionality. This study evaluated five commonly used alternatives for seismic retrofitting shear-deficient beams. Future research could explore additional options, including fiber-reinforced polymeric materials and innovative composite materials, such as concrete composite linings and fiber-reinforced cement mortars. Further studies could also incorporate criteria that address the final capacity characteristics of the retrofit element and address the need for resilient buildings capable of recovering quickly after an earthquake to maintain functionality in a shorter time frame. Additionally, the application of MCDM methods could be improved by integrating approaches to manage the uncertainty inherent in expert opinion and considering interactions between criteria, ultimately improving the robustness of solutions. This study represents a result of teamwork Conceptualization, P.V., B.G. and V.Y. ; methodology, P.V., B.G. and V.Y. ; validation, P.V. and B.G. ; writing--original draft, P.V. and B.G. ; writing--review and editing, V.Y. ; resources, V.Y. ; supervision, V.Y. ; project administration, V.Y. ; funding acquisition, V.Y. All authors have read and agreed to the published version of the manuscript. **Funding:** Grant PID2023-150003 OB-I00 funded by MCIN/AEI/10.13039/501100011033 and by \"ERDF A way of making Europe\". **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.