## 5 Discussion  
In the search for optimal seismic retrofit strategies, the scientific community has predominantly relied on traditional MCDM methods, often overlooking innovative approaches that could provide better solutions. This study presents a comprehensive methodology for ranking seismic retrofit alternatives using emerging MCDM techniques. The methodology integrates functionality with the three pillars of sustainability-economic, environmental, and social life cycle analysis. The proposed approach is applied to evaluate and rank five seismic retrofit alternatives for a reinforced concrete beam with shear deficiencies. These retrofit alternatives were designed to achieve the same increase in shear strength to meet seismic regulations. The analysis considers a time frame beginning from the implementation of the retrofit and extending up to a useful life of 50 years or until the beam sustains damage from an earthquake. The inclusion of specific preventive maintenance, tailored to the material characteristics of each alternative, ensures the validity of this time frame. This approach eliminates the possibility of one retrofit alternative having a longer lifespan, allowing for a fair comparison [17]. Determining the shear capacity of reinforced concrete beams remains an evolving area of research. Most shear design methods use an additive approach, combining the contributions of concrete and steel. However, Eurocode 2 considers only the steel contribution to shear strength [10], which can lead to an underestimation of the shear capacity in lightly shear-strengthened beams where the concrete contribution is more significant [11]. This manuscript's methods for designing the retrofitting alternatives are based on an additive \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Alternatives**} & **EDAS** & \multicolumn{2}{c}{**MABAC**} & \multicolumn{2}{c}{**CODAS**} & \multicolumn{2}{c}{**MARCOS**} \\ \cline{2-9}  & **Score** & **Ranking** & **Score** & **Ranking** & **Score** & **Ranking** & **Score** & **Ranking** \\ \hline CJ & 0.01 & 5 & \(-\)0.40 & 5 & \(-\)1.83 & 5 & 0.31 & 5 \\ SCJ & 0.34 & 4 & \(-\)0.06 & 4 & \(-\)0.75 & 4 & 0.43 & 4 \\ STE & 0.99 & 1 & 0.28 & 1 & 0.76 & 2 & 0.66 & 2 \\ STA & 0.85 & 3 & 0.19 & 3 & 0.66 & 3 & 0.63 & 3 \\ CFRP & 0.98 & 2 & 0.27 & 2 & 1.17 & 1 & 0.70 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Classification of alternatives with MCDM. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Dimension** & **Weight** & **Criteria** & **Global Weight** \\ \hline Economic (D1) & 0.27 & C1 & 0.19 \\  & & C2 & 0.08 \\ \hline Environment (D2) & 0.23 & C3 & 0.16 \\  & & C4 & 0.07 \\ \hline Social (D3) & 0.17 & C5 & 0.08 \\  & & C6 & 0.09 \\ \hline Functionality (D4) & 0.33 & C7 & 0.13 \\  & & C8 & 0.20 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Weights derived from BWM. approach that considers the contributions of concrete, steel, and composites. This approach resulted in comparable increases in shear strength capacity across the different retrofit alternatives, assuming that all resistance mechanisms reach their maximum values simultaneously without any interaction between them. Although this additive approach is widely accepted, recent research has indicated potential interactions between the experimental strength contributions of FRP shear reinforcement [45]. The relatively high increase in shear force observed in the concrete-based alternatives is mainly due to construction limitations, as additional concrete is required even when it is not structurally necessary [43]. For alternatives involving steel plates, the contribution to shear stress is considered a function of the depth and thickness of the continuous plates. However, in the case of STE, where the plates are not fully anchored to the concrete, they may not reach maximum strength at the elastic limit.