Shear Behavior of Steel-Fiber Reinforced Ultra-High-Strength Self-Compacted Concrete Beams
Ultra-high-strength concrete is a new class of concrete that has been the result of the progress in concrete material science and development. This new type of concrete is characterized with very high compressive strength; about 100 MPa. Ultra-high strength concrete shows very brittle failure behavior compared to normal-strength concrete. The development and use of self-compacting concrete has provided a solution to the workability issue. The combination of technology and knowledge to produce Ultra-High strength fiber reinforced self-compacting concrete was proved to be feasible. Few studies investigated the effect of incorporating steel fibers on the shear behavior OF ultra-high-strength reinforced concrete beams.
The research consists of a test series and analytical investigation. The present research investigated the shear behavior of reinforced beams made of normal-strength-concrete fiber-reinforced self-compacting concrete (28MPa), high-strength concrete fiber-reinforced self-compacting concrete (60 MPa) and ultra-high-strength fiber reinforced self-compacting concrete (100 MPa). The test parameters included two different shear span-to-depth ratios of 2.22 (deep beam action) and 3.33 (slender beam action), and three different steel fiber volume fractions of 0.4%, 0.8%, and 1.2%. The test results showed that the shear strength gain ranged from 20% to 129% for the beams having a concrete grade of 28 MPa, 26% to 63% for the beams having a concrete grade of 60 MPa, and 8.6% to 94% for the beams with a concrete grade of 100 MPa. For the deep beams, the shear strength gain tended to decrease by increasing the concrete grade. For the slender beams with steel fiber volume fractions of 0.4% and 0.8%, varying the concrete grade had no obvious effect on the shear strength gain. For the slender beams with the higher steel fiber volume fraction of 1.2%, the shear strength gain tended to decrease with an increase in the concrete grade.
In the analytical investigation, the accuracy and validity of published analytical models have been demonstrated. Predictions of analytical models by Ashour et al. (1992) and Narayanan et al. (1987) were in good agreement with the experimental results.