Shear Behavior of Reinforced Concrete Beams with Vertical Holes externally Strengthened with near Surface Mounted Bars

Electromechanical and other service ducts must be carried vertically through structural components. The majority of researches have examined the strengthening of the transverse opening region in concrete beams. Since no one has examined beams with vertical openings, the current study focuses on this topic. The shear behavior of RC beams externally strengthened with near surface mounted (NSM) steel bars and featuring vertical holes was the main focus of this article. Ten RC beams measuring 120 mm in width, 200 mm in depth, and 1100 mm in length were subjected to experimental flexural testing. Six specimens were strengthened using various NSM techniques, whereas four specimens were tested without strengthening. The hole region was traversed by cold-formed steel sheet, straight horizontal and vertical NSM bars, and horizontal NSM bars with bent ends. The study's primary characteristics are the hole diameter (20, 30, and 50 mm) and the strengthening provided by various NSM systems. Shear cracking load, failure pattern, ultimate load capacity, load-deflection relation, and energy absorption of the tested specimens were presented, and the findings were examined and compared. The results showed that the vertical openings had no discernible effect on the stiffness of unstrengthened beams. However, the load capacity of the unstrengthened beams with hole diameters of 20 mm, 30 mm, and 50 mm, respectively, was decreased by 4.55%, 9.09%, and 19.7%, while the energy dissipation capacity of the same specimens was decreased by 4.18%, 8.6%, and 16.46%, respectively. In comparison to an unstrengthened specimen with a 50 mm diameter hole, the shear resistance increased by 95% when horizontal NSM bars, with or without end anchorages, were installed in the beams. When compared to the un-strengthened specimens with holes, all NSM techniques improved the energy dissipation capability for all specimens. Ultimate load of the tested beams was predicted and compared with experimental ones.