Experimental and analytical investigation on effect of openings in behavior of reinforced concrete deep beam and enhanced by CFRP laminates

Abstract

This work studies the potential of producing web openings within the shear span for the reinforced concrete (RC) deep beams. Carbon fiber reinforced polymer (CFRP) laminates are used to improve the shear strength. 13 specimens with dimensions of 120, 750, and 1800 mm are prepared for the tests. Shapes of the web openings are square and circular with diameter of 230, 300, and 370 mm. Their locations are in the center, upper and lower of the shear span. Three angles for wrapping 0°, 45°, and 90° are used to strengthen the beams with circular openings. The shear strength of RC deep beams decreased in the range of 22–74 % depending on the diameter, location, and shape of the openings. While CFRP improved the shear strength, stiffness and toughness in about 17–48 %, 0.7–17 % and 4–20 % respectively. The previous percentages depended on size of openings and the orientation of CFRP laminates in RC deep beams with circular openings. The laminates of CFRP are able to repair and restore the bearing capacity of beams by approximately 100 % of the same beams before they failed. On the other hand, Strut and Tie method established to estimate the maximum strength of the RC deep beams and it results that the theoretical method succeeded in guessing the practical results.