The effect of beam depth on the shear behavior of reinforced concrete beams externally strengthened with carbon fiber–reinforced polymer composites

Abstract

The primary objective of this article is to study the effect of beam depth on the performance of shear-deficient beams externally strengthened with carbon fiber–reinforced polymer composites. The investigated parameters include overall behavior up to failure, the onset of the cracking, crack development, and ductility. The experimental results showed that externally bonded carbon fiber–reinforced polymer increased the shear capacity of the strengthened reinforced concrete beams significantly depending on the variables investigated. The use of carbon fiber–reinforced polymer composites is an effective technique to enhance the shear capacity of reinforced concrete beams. For the beams tested, as the depth of the reinforced concrete beams was increased from 225 to 450 mm which is equivalent to a/ d ratio of 2.7–1.2, respectively, there was corresponding 15%–19% increase in contribution of the carbon fiber–reinforced polymer strips in terms of ultimate load. The impact of the beam depth is more pronounced on the ultimate load than the corresponding deflection of the control and strengthened beams. The results indicated that the beam depth has an influence on the angle at which primary cracking angle varied from 33, 44, 50, and 54 for beam of a/ d of 2.7, 1.9, 1.5, and 1.2, respectively. If the shear crack crossed carbon fiber–reinforced polymer strips above its development length, the carbon fiber–reinforced polymer strips could not be expected to reach its ultimate strength and was thus only partially effective as observed in beams with different depths.