Enhancement of the Shear Capacity of RC Deep Beams with Ultra-High Performance Fiber-reinforced Concrete

This research investigates the shear behavior of Reinforced Concrete (RC) deep beams strengthened with Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC). For this purpose, eight RC deep beams were fabricated and tested for failure. One beam served as a control beam (un-strengthened), while the remaining seven deep beams were strengthened utilizing various strengthening schemes. This experimental study primarily focused on the thickness of the UHPFRC layer, Steel Fiber (SF) volume fraction, and strengthening schemes (jacketing, bilateral layers, and strips exclusively in the shear zone). The experimental findings demonstrated that UHPFRC significantly enhanced the shear capacity, toughness, and stiffness of the RC deep beams. The performance of the strengthened beams exhibited improvements in ultimate shear strength, stiffness, and toughness of about 43.6%, 102.2%, and 171.3%, respectively, higher than that of the un-strengthened deep beam. UHPFRC U-jacketing is a highly effective method for strengthening the RC deep beams. Incorporating SF into the UHPFRC mixture improved the shear properties of the strengthened specimens and delayed fracture propagation. Finally, the shear capacity of the strengthened specimens was compared to the values predicted by the analytical approaches presented in earlier research.