Experimental study of depth-dependent flexural behavior of plain and bar-reinforced ultra-high-performance hybrid fiber-reinforced concrete

Abstract

The popularity of ultra-high-performance fiber-reinforced concrete (UHFRC) is increasing due to its superior strength and durability. Despite the potential, its implementation is limited by a need to understand how UHFRC-based structures behave in the real world. In this study, UHPFRC beams were prepared using a tri-ternary combination of three microsteel fibers. The research was conducted on 17 plain and bar-reinforced beams of different depths to determine their structural behavior. Compared to plain UHFRC beams, reinforced UHFRC beams exhibit more shear-flexural crack diffusion. As a result of the combined UHFRC matrix and steel bars, multiple cracking responses occurred before fiber pullout occurred. The crack widths ranged from 7 to 11 mm at their maximum in all beams. Upon post-yielding moment–curvature analysis, all beams showed highly nonlinear behavior. It was found that plain beams were less stable against nonlinear curvatures than bar-reinforced beams. Based on the results of this study, the beam's ductility was not significantly affected by bar reinforcement. This study revealed that reinforcement of the beam by bars did not significantly affect its ductility. A nearly uniform ductility of plain and bar-reinforced beams may be attributed to the hybrid fibrous systems in UHFRC beams.