A New Strengthening Technique for Reinforced Concrete Corbels Openings Using Steel Plates

Abstract This study aimed to study the behavior of corbels with openings and aimed at examining the potential use of strengthening reinforced concrete (RC) corbels that had openings with steel plates. Experiments were done to examine the load-bearing capacity of ten corbels having square, circular, horizontal, and vertical holes. All corbels had symmetrical cantilever projections that measured 250mm long, 160mm wide, 240mm deep at the column face, and 80mm deep at the free end. Test parameters included the opening shape, the presence and absence of horizontal ties, and steel plates. There are three tested groups: group A included three corbels with horizontal ties, group B included three corbels without horizontal ties, and group C included four corbels, strengthening two corbels from group A and two corbels from group B. The results showed that the vertical opening has a greater impact than the horizontal opening in terms of maximum load. Also, the absence of horizontal closed ties increases cracking load by about 25%, decreases maximum load by about 16%, and increases service deflection by about 385%. On the other hand, corbels without horizontal ties had a negative effect on openings. The degradation in ultimate load and cracking load was about 16% and 25%, respectively, and the increase in service deflection was about 299%. The presence of the square opening reduced the maximum load by 13%, increase service deflection about 156%, decrease cracking load about 31%. Also, strengthening results have the greatest effect on vertical openings. The strengthening of corbels with openings by using steel plates showed that the greatest compensation for lost strength was in corbels without horizontal ties. The enhancement in ultimate load was about 33% more than corbel without steel plates and 12% more than reference without opening.