Experimental Comparison of Shear Behavior of Plain and Fiber Reinforced Concrete Beams with Continuous Rectangular Spiral Reinforcement

In general, shear reinforcement in reinforced concrete beams typically involves the use of stirrups. However, substituting stirrups with continuous rectangular spiral reinforcement can enhance construction efficiency and lower costs. Meanwhile, the adoption of fiber-reinforced concrete in concrete structures is on the rise due to its distinctive properties. To address the tensile and shear vulnerabilities of concrete, reinforcing it with fibers is a viable solution. This study explores the experimental replacement of stirrups with continuous rectangular spiral reinforcements in both traditional concrete and steel fiber-reinforced concrete (SFRC) beams. Three beams were subjected to static loading tests: the first beam, referred to as ST-NC, featured stirrups and normal concrete as a reference; the other two beams incorporated continuous rectangular spiral reinforcements with normal concrete (SP-NC) and steel fiber-reinforced concrete at a 0.75% volume fraction (SP-F0.75). The experimental findings indicate that the beam reinforced with continuous rectangular spiral reinforcements and fiber concrete exhibits improved shear resistance, energy absorption, and ductility compared to the normal concrete beam and the reference beam. The beams with continuous rectangular spiral reinforcements, using normal concrete and steel fiber-reinforced concrete, demonstrated a 23.8 and 46.5% increase in shear capacity, respectively, compared to the reference beam. Additionally, energy absorption in SP-NC and SP-F0.75 beams increased by 69 and 158%, respectively, compared to the reference beam. The ductility of the continuous rectangular spiral reinforcement beam with normal concrete and steel fiber-reinforced concrete is 0.87 and 1.17 times that of the reference beam, respectively. Notably, the results reveal a reduction in the ductility of the SP-NC beam compared to the reference beam, and the addition of 0.75% by volume of fibers to the concrete resolves this ductility weakness in the SP-NC beam. These findings underscore the advantages of employing continuous rectangular spiral reinforcements in beams constructed with steel fiber-reinforced concrete, as proposed in this study