# An Experimental Study on Repairing of Reinforced Concrete Beams Having Damaged Longitudinal Bars
## 4 Conclusions  
Experimental analysis of different techniques of repairing beams that were previously damaged at mid-span by cutting off the bottom steel reinforcement bars resulted in the following conclusions:  
1. All repaired beams had significant enhancements in behavior and capacity as compared to the damaged beam. Among all the repaired specimens, the RB7-EBR-S specimen exhibited higher load-carrying capacity and rigidity than those of the undamaged specimen, indicating a promising result in the repair of damaged beams. Nevertheless, none of the specimens achieved the ductility and energy absorption capacity of the undamaged reference specimen. 2. The load-carrying capacity, rigidity, and energy absorption capacity of the specimen repaired using the NSM method (RB3-NSM-G) were found to be higher than those of the specimen repaired using the SNSM method (RB2-SNSM-G), which is consistent with results obtained in a study in the literature [36]. The ductility values were quite similar for both methods. 3. Repair with the SNSM and EBR methods using steel rebar resulted in a significant enhancement of beam capacity and behavior. Flexure cracks and yielding of steel were observed. This behavior was not similar in beams with GFRP, where the splitting of the bars from mortar embedment governed the behavior and capacity. A study in the literature [35] presented similar results showing that the load-carrying capacity andstiffness of beams reinforced with SNSM-steel bar were generally more significant than those of the identical beams strengthened with SNSM-GFRP bar. 4. Repairing beams with the EBR technique using CFRP sheets with a U boundary enhanced the capacity of the beam significantly as compared to the beam without the U boundary, which is consistent with similar results obtained in some studies in the literature [17, 50, 51]. It can be said that the U boundary is effective in delaying debonding while also improving both load-bearing capacity, ductility, and energy absorption capacity. The beam repaired with the EBR technique using a CFRP sheet and U boundary failed in sheet rupture, while the beam without a U boundary failed in the separation of the lower sheet. However, its performance was generally less effective than that of the beams repaired with the EBR technique using steel bars. 5. Damaged beams mostly developed a single wide crack at the damaged location, which propagated upwards. This failure behavior was common, along with the splitting failure of repaired beams using GFRP bars and separation of an added EBR mortar layer in both cases of using GFRP and steel rebars. The specimens repaired using steel bars behaved in a more ductile manner. The beam repaired with the SNSM technique using steel rebars developed a flexure failure mode with flexure cracks like the reference beam. 6. Enhancement of energy absorption capacity was observed in all beams compared to the damaged beam. Although an increase of up to 1401% in energy absorption capacity was observed in the repaired beams compared to the damaged beam, this value remained significantly lower than that of the undamaged reference beam. 7. The repaired beams utilizing the SNSM technique (RB2-SNSM-G) demonstrated greater energy absorption capacity and ductility compared to those repaired with the EBR technique (RB8-EBR-G), although the beams repaired with the EBR technique exhibited higher rigidity and load capacity. Conceptualization, M.B.S., V.E. and H.T.K. ; methodology, M.B.S., V.E. and H.T.K. ; formal analysis, M.B.S., A.G., S.Y. and V.E. ; investigation, M.B.S., A.G., S.Y., V.E. and H.T.K. ; resources, M.B.S. and M.O. ; writing--original draft preparation, M.B.S. and M.O. ; writing--review and editing, A.G., S.Y. and H.T.K. ; visualization, M.B.S. and A.G.; supervision, H.T.K. ; project administration, M.B.S., V.E. and H.T.K. ; funding acquisition, M.B.S., V.E. and H.T.K. All authors have read and agreed to the published version of the manuscript. All authors have read and agreed to the published version of the manuscript.