Predicting the post-cracking behavior of normal- and high-strength steel-fiber-reinforced concrete beams

In this paper, the results of analytical and experimental analyses for the flexural response of steel-fiber-reinforced concrete (SFRC) beams are presented. In the analytical part, to predict the flexural response of SFRC beams according to the strength of concrete and steel fiber content, a model for compression was adopted from a previous research and a trilinear tension-softening curve (TSC) was suggested based on inverse analysis. To obtain the TSC, a number of notched SFRC beams with two parameters such as (1) strength of concrete (normal- and high-strengths) and (2) steel fiber content (0.0%, 0.5%, 1.0%, 2.0%) were fabricated and tested in accordance with the Japan Concrete Institute (JCI) standard. The suggested models were verified through a comparison of the previous four-point flexural test results and the sectional analyses. For the experimental part, the compressive strength and elastic modulus showed negligible changes with the inclusion of steel fibers, while the strain capacity and post-peak behavior were improved by including steel fibers. The addition of more than Vf of 1.0% steel fibers resulted in the significant improvement of flexural strength, deflection capacity, and post-peak ductility, while the increase of compressive strength led to an increase in the flexural strength and a decrease in the post-peak ductility. Lastly, the fracture energy increased with the increase in the fiber content and the decrease in the strength.