Experimental investigation for structural behaviour of self-compacting reinforced concrete hollow beams with in-place circular openings strengthened with CFRP laminates

This study aims to experimentally examine the structural behavior of self-compacting concrete hollow beams containing in-place circular openings in various positions. The studied parameters were the number and positions of openings that are strengthened or not strengthened by CFRP with multiple schemes. For this, seven reinforced self-compacting concrete hollow beams of identical properties were tested under two concentrated and symmetrical loading. The experimental work included two groups of beams in addition to one control beam (beam without opening). The first group comprised three beams with an opening (s) in the front and rear of the web, while the second group contained three beams with an opening (s) in an identical position of the first group, strengthened by CFRP laminates. Results revealed that all reinforced concrete specimens with openings suffered from higher deflection owing to the reduction in their stiffness. Moreover, decreases in the ultimate failure loads were noticed for the first group ranged from 9.5% to 16%. In contrast, the reduction ratios for the second group of beams were with lower ranges. Regarding the first group of beams, the values of the ductility indices were less than two when compared with the control beam. On the other hand, higher values of the ductility indices were recorded for the beams in the second group compared with the unstrengthened beams in the first group.