The Influence of Amount and Aspect Ratio of Fibers on Shear Behaviour of Steel Fiber Reinforced Concrete

In this study, two grades of concrete namely C30 and C50 were investigated for the direct shear behavior of plain and steel fiber reinforced concrete. Shear tests were performed on concrete beams, 100 x 100 x 300 mm, reinforced with two different aspect ratios (l/d) of steel hooked-end fibers 65 and 80 and three percentages of fibers 0.5, 1.0 and 1.5 % by volume of concrete. The water/cement ratios (w/c) used were 0.5 and 0.43. The main objective of this study was to study the shear behavior of plain and fiber reinforced concrete at different aspect ratios and at different volume fractions of steel fibers. Test results for C30 and C50 concretes showed that, as the volume fraction of fibers increased from 0 to 1.5%, the shear strength increased about 2.15 and 2.46 times that of plain concrete, respectively. Also, test results showed that the aspect ratio of steel fibers has no clear effect on the shear strength. Relationships between shear strength and volume of fibers were determined, and a relationship obtained in terms of fiber factor and compressive strength to estimate the shear strength of fiber reinforced concrete. The obtained equations give good correlation with the experimental results.