Response of Reinforced Concrete Tapered Beams Strengthened Using NSM-CFRP Laminates

Abstract

The present study is about an experimental investigation of the strength and response of reinforced concrete tapered beams strengthened by near surface mounting (NSM)-CFRP technique. The influence of several parameters on the behavior of beams is investigated. And those parameters are: angle of inclination and strengthening patterns by NSM-CFRP technique. The experimental program involved testing nine specimens of reinforced concrete tapered beams and one prismatic beam. There were two groups in the experimental program; the first group included four unstrengthening reference beams to investigate the effect the angle of inclination, and the second group included six specimens were strengthened by NSM-CFRP strips with different strengthening patterns (U-strips) and (UL-strips) were used to strengthen the tapered beams against shear and flexural forces. The results of the experiments indicated that as the angle of inclination increased, from (0˚) to (7°), (14°) and (21°) decreases the ultimate load capacity (Pu) by about (4)%, (14)% and (41)% respectively for unstrengthen tapered beams, as well as the deflection at the ultimate load. Also, when compared unstrengthen with strengthened beams, the ultimate load capacity will increase with the angle of inclination increased, from (0˚) to (7°), (14°) and (21°), for (U-strips) patterns the percentages of increase were (7)%, (9)% and (33) % respectively, while (UL-strips) increased the ultimate load capacity by about (19)%, (19)% and (44)% respectively.