Experimental Analysis of Reinforced Concrete Deep Beams with Circular Openings Strengthened by GFRP and Steel Bars

This study investigated the behavior of deep beams with openings that have been reinforced with GFRP and steel bars. A total of 14 reinforced concrete deep beams having a rectangular cross-section of 150 × 500 mm and a total length of 1600 mm were constructed with or without openings and tested up to failure under a four-point bending test. The parameters studied were the opening diameter (140 and 240 mm), number and location of the openings and the shear span-to-depth ratio (a/d). These beams were divided into Group I (a/d = 0.9) and Group II (a/d = 0.5). In each group, one beam had no opening to serve as the control beam. Two beams had one opening in the shear area, two had one at the mid-span of the beam and two had two openings, one on each side of the beam. Finite element modeling with strong correlation with the laboratory results was performed. The results showed that an increase in a/d caused a decrease in the final strength of the beam. The number of openings and their locations on the load transfer path were factors that significantly reduced the ultimate load borne by the beam. Comparison of the test results with the relations provided in design regulations indicated that the ultimate strengths of the beams were higher than the values obtained from the regulations. On average, the values calculated based on ACI 318–19 and Canadian S806-2012 were 86.95 and 55.55% lower than the test results, respectively.