## 4 Conclusions  
The behavior of over-reinforced concrete beams strengthened with bolt-compression steel plates (BCSPs) was investigated in this study. Based on a comparison of the experimental tests and the numerical results, the following conclusions can be drawn:  
1. From the results of the experimental test, the load-carrying capacity and EA of the BCSP beams increased with the increase of the steel plate thickness in comparison with the control beam. The peak load-capacity of the BCSP beams ranged from 73.7% to 149% that of the CB. It was also observed that the increase in EA was about 247.5%, 317.5%, and 458.3% for the beams with 6 mm, 10 mm, and 15 mm steel plate thicknesses, respectively. 2. Strengthening of over-reinforced concrete beams can be accomplished using steel plates. The BCSP system controls the spalling of the concrete cover at the compression section and increases the ductility, stiffness, and EA by improving the compressive strength. This implies that there is a change of failure mode, with steel yielding from the brittle failure of the CB to the ductile failure of the BCSP beams, which depend on the thicknesses of the steel plates. 3. Generally, there was a mild increase in the member stiffness of the BCSP beams over the CB after cracking. The plates exerted higher reactions against downward displacement, preventing the BCSP beam section from failing. 4. Applying bolts to the steel plates increased the confinement of the arrangement prior to bonding. The plate increased the compressive strength of the beam. These phenomena influenced the mode of failure of the beams, and, as a result, there was a significant reduction in the amount of horizontal cracking. Hence, failure occurred more readily on the surface than at the compression zone. The BCSP-15 beam, which had the greatest plate thickness, also experienced the best confinement effect on the development of its failure mode, resulting in a failure load increase. 5. The concrete failure characteristics were satisfactorily and accurately predicted using the damaged plasticity model. The load transfer between the steel plate and concrete were simulated using the cohesive behavior method model. This displayed very satisfactory results. 6. Based on comparisons between the experimental and FE analysis of the curves' mid-span displacement under load, EA, and crack patterns with varying failure modes, it can be concluded that the proposed model is in accordance with the test results. Therefore, FE models used here can be used for further investigation. 7. The implication of these observations is that there is a potentially beneficial reduction of steel bars at the compression zone when using a bolt-compression steel plate for strengthening. This plate can yield a reduction in the cost of the overall materials used, as well as increase durability, since the same strength levels can be reached at a reduced area fraction when using the developed system. Figure 18: Comparison between (**a**) the experimental tests with the FE modelling of the (**b**) compressive and (**c**) tensile damage cracks in the BCSP-15 beam at the point of failure. **Author Contributions:** Conceptualization, S.A., Z.I. and P.S. ; Data curation, S.A.; Formal analysis, S.A.; Funding acquisition, S.A.; Investigation, S.A., Z.I. and P.S. ; Methodology, S.A., Z.I. and P.S. ; Project administration, S.A. Software, S.A., A.J. and K.N. ; Supervision, Z.I. and P.S. ; Validation, S.A.; Visualization, S.A., A.J. and K.N. ; Writing--original draft, S.A.; Writing--review and editing, S.A., Z.I., P.S. and A.J. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received the funding no (project number: GPF015A-2018) by the Faculty Research Grant of the University of Malaya (UM). **Acknowledgments:** The authors are interested in expressing their gratitude for the support provided by the University of Malaya (UM).