Effect of steel fibers on the shear behavior of Self-Compacting reinforced concrete deep Beams: An experimental investigation and analytical model

Abstract

The shear behavior of reinforced concrete deep beams made of self-compacting concrete with different volume fractions of discrete macro steel fibers (0.5%,1.0%, and 1.5%) is studied. All the beams are tested at shear span to depth ratio of 1.0, and the effect of loading plate width on shear carrying capacity is also studied. Similarly, the effectiveness of steel fibers in improving the shear behavior is compared with the beams made of plain concrete and the beams with 0.3% web reinforcement in both horizontal and vertical directions. Test results revealed that the addition of macro steel fibers significantly improved the performance of deep beams, particularly first cracking load, ultimate shear capacity, ultimate deformation, and ductility. However, the addition of steel fiber more than 1.0% volume fraction did not increase the ultimate shear capacity. A simplified analytical model is proposed to predict the ultimate shear capacity of steel fiber reinforced concrete deep beams. The existing cracking strut and tie method (CSTM) is extended to include the effect of fibers, and a simplified fiber-reinforced cracking strut and tie method (FR-CSTM) is proposed. Predictions of FR-CSTM are compared with CSTM and two-parameter kinematic theory (2PKT). The comparisons of predictions with test results and existing models show that the proposed method can capture the ultimate shear capacity of deep beams with reasonable accuracy.