Experimental Investigation on Flexural Strengthening of Reinforced Concrete Beams with Opening Using Heavy-Duty Metal Straps

It is proven that beam openings have an inverse effect on the beam's strength. To enhance the beams' overall resistance to applied loads and to improve their ductility, failure mode, and first cracking load, strengthening is necessary. This study investigates the effects of using heavy-duty metal straps (HDMS) to strengthen reinforced concrete (RC) beams with openings. Seven RC beams with dimensions of 250 mm high and 150 mm wide and a clear span of 1200 mm were tested. Six of them had an opening in the middle of the RC beams' span, while one of them was a solid control specimen. The shape of the opening and the method of HDMS application were the main variables. The circular opening had a diameter of 110 mm, while the square opening was 100 mm × 100 mm, which yields approximately equal areas. The HDMS was applied vertically or horizontally around the openings. The horizontal HDMS strengthening can increase the load-carrying capacity by 110% and 115% compared to the solid control beams for circular and square openings, respectively. The strengthened beams with vertical HDMS deflected by up to 179% and 160% compared to the solid beams, respectively. Finally, vertical strengthening delays the first cracking load of the tested specimens by 116% and 105% for circular and square openings, respectively, compared to a non-strengthened opening beam.