Effect of steel fiber on the shear behavior of reinforced recycled aggregate concrete beams

In this research, the influence of using steel fibers on the shear action of reinforced concrete beams, made of recycled concrete aggregate (RCA), was investigated through experiment and finite element analysis (FEA). First, 12 reinforced concrete beams were tested with varying amounts of steel fibers. These beams contained normal concrete aggregate (NCA) as reference beams besides RCA beams. All beam models had the same 150 mm x 250 mm cross-section and 2000 mm length. The beams had three bars of 16 mm reinforcement and two bars of 12 mm reinforcement at its bottom and top, respectively. Three replacement ratios of recycled aggregate (RA) were considered; 0%, 30%, and 70%. Moreover, steel fibers were introduced in the beams at 0%, 0.5%, 1%, and 1.5% content by volume. The beams were evaluated under a four-point bending test while the load-deflection diagram and failure load for all beams were considered as the criteria for comparing the shear response of different beams. A thorough FEA was carried out using ANSYS to model these beams. The FEA results were compared with the outcomes of the experimental tests, and a clear agreement was obtained. The results showed that using steel fibers improved the shear strength of the beams by 2.94%, 15.88%, and 34.71% for NAC beams, 1.39%, 11.11%, and 16.67% for 30% RCA beams, and 24.53%, 40.57%, and 59.44% for 70% RCA beams, respectively by using steel fibers with ratios of 0.5%, 1%, and 1.5%, respectively.