## 5 Discussion
To take this into account, previous studies [40; 46] have introduced modification factors that consider the tensile capacity of the concrete at the concrete-adhesive interface, with a reduction factor of 0.76 being applicable in this case. For the STA, the contribution of the bolts to the shear capacity could also be considered [46]; however, theoretical models to accurately predict shear capacity are still under development [47]. The depth of the beam below the slab limits the bond length or connection length of the steel and CFRP coatings. As a result, the bond length can be shorter than the required development length, leading to premature failure of the rehabilitation system and limiting the effective utilization of the high-strength properties of the laminates. For the STE alternative, steel plates contribute more significantly to the shear resistance of the beam when the ratio of plate depth to beam depth reaches its maximum feasible value. Studies have shown that, for ratios greater than 0.75, the contribution of the plate remains unchanged, which is particularly advantageous for T beams and beams located under slabs [40]. In this study, the ratio was 0.70. On the other hand, shear reinforcement using CFRP laminates with anchors can increase shear capacity by approximately 20% or more compared to CFRP laminates without anchors [48; 49]. However, the ACI 440 design guidelines provide conservative and reliable predictions, guaranteeing safe retrofitting designs for beams with a shear deficiency with CFRP laminates [50]; there are currently no standardized guidelines for anchor design. By analyzing the cost-effectiveness of the retrofitting alternatives, their economic viability can be assessed by determining the cost required to achieve a 1% increase in shear strength [51]. Table 7 presents the retrofitting costs obtained through LCCA for a 1% increase in shear strength in the different alternatives. Among the alternatives, the SCJ method demonstrates the lowest cost per 1% increase in shear strength, making it the most cost-effective option. In contrast, the CFRP alternative incurs the highest costs. However, despite its cost-effectiveness, concrete jacketing has certain drawbacks, especially in labor-intensive construction processes, long execution times, and reduced usable space inside the building [52]. The viability of the retrofitting strategies was evaluated using two criteria: C7-Duration of the work and C8-Architectural impact. The results indicate that CJ has the highest value for C7, while both CJ and SCJ have the highest values for C8. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Alternatives** & **CJ** & **SCJ** & **STE** & **STA** & **CFRP** \\ \hline Shear force increase ratio (\%) & 29\% & 29\% & 33\% & 33\% & 22\% \\ \hline Cost LCCA a & 504.19 & 279.74 & 359.32 & 418.82 & 507.16 \\ \hline Cost to increase the strength by 1\% a & 17.39 & 9.65 & 10.89 & 12.69 & 23.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Cost-effectiveness of the alternatives. Retrofitting alternatives involving the use of concrete generate significant environmental, social, and functional impacts. These high environmental impacts and associated social consequences are primarily due to concrete production, further exacerbated by the large quantities required for these retrofit methods, even when not structurally necessary. The environmental and social impacts of SC are lower than CJ due to the reduction of structural adhesive in the retrofit process. Although the shotcrete and equipment required for SCJ are more expensive than conventional concrete, the cost of SCJ is reduced by avoiding extensive formwork systems and the reduction of structural adhesives required for CJ. Alternatives that include concrete have notable architectural impacts, but CJ has the highest execution time, contributing to its lower ranking. Consequently, CJ and SCJ are ranked fifth and fourth among the retrofit alternatives.