## 5 Conclusions  
This paper builds upon previous research that proposed a retrofitting method for reinforced concrete beams using modularized steel plates. In this study, a bolted connection between steel plates was introduced to address the debonding issue observed in previous research. Moreover, the structural performance of the modularized steel plate was analyzed based on the size of an individual module unit. The main conclusions drawn from this study are as follows.  
1. The modularized steel plate retrofitting technique was effective in influencing crack propagation in retrofitted RC beams. Specimens retrofitted with this method displayed more flexural cracks in tension zones and exhibited narrower shear crack widths compared to non-retrofitted beams. A key observation was deviation of the flexural behavior due to insufficient connections between the steel plates. This highlighted the significance of robust interconnections to ensure cohesive behavior and to prevent debonding. Furthermore, the interplay between module dimensions and their corresponding loading points became apparent. Concentrated loading at the end of a module increased susceptibility to forces that could lead to debonding. This emphasizes the necessity of aligning module dimensions with anticipated loads and the mechanism of load transfer;
2. Retrofitting using the modularized steel plate method significantly enhances the maximum load and stiffness of existing RC beams. Specimens retrofitted with these plates demonstrated maximum load 1.6 times that of non-retrofitted beams. Additionally, interconnected steel plates increased the load capacity by about 25% compared to isolated plates. Both the load application point and module size were crucial in determining modularized steel plate performance;
3. The use of modularized steel plates for retrofitting RC beams resulted in a marked increase in ductility, with certain specimens showing almost double the ductility. Specimens with interconnected plates had a ductility index approximately 1.6 times that of those without. Tensile forces were shared between the steel plate and the original RC beam, indicating that the modularized steel plate effectively handles tensile forces. Additionally, the strain levels within these plates increased as they neared the beam's tension zone, emphasizing the importance of effective bonding;
4. The evident differences of load, stiffness, and ductility between specimens with interconnected steel plates and those without highlight the necessity for shear and flexural strength formulas tailored to the connection method. While this research focused on a limited set of specimens to study the effects of steel plate interconnections, future research should include a broader specimen range for a more comprehensive assessment of flexural and shear performance.  
**Author Contributions:** Conceptualization, K.M.R. and Y.H.L.; methodology, K.M.R. and M.S.K.; validation, Y.H.L.; formal analysis, K.M.R. and M.S.K.; investigation, K.M.R. and Y.H.L.; writing--original draft preparation, K.M.R.; writing--review and editing, Y.H.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2019R1A2C1090033 and No. RS-2023-00218832).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare no conflicts of interest.