Ali Ghiami Bajgirani - Assistant professor, Department of civil engineering,The Institute of Higher Education of Eqbal Lahoori, Mashhad, Iran
Soroush Moghadam - Lecturer, Department of civil engineering,The Institute of Higher Education of Eqbal Lahoori, Mashhad, Iran
Shahriar Tavousi Tafreshi - Assistant professor, Department of civil engineering,Azad University Central Tehran Branch, Iran
Amirhossein Arbab - B.S. Educated of civil engineering, The Institute of Higher Education of Eqbal Lahoori, Mashhad, Iran

on different parameters such as aspect ratio of fiber, the geometrical shape of fiber and placement of fiber in concrete. This article deals with the effect of aspect ratio of steel fibers on resistance characteristics in fiber reinforced concrete such as concrete workability, compressive strength, tensile strength and resistance against impact by consideringStructural behavior of steel fiber that steel fibers length were 3.5, 6.5 and 8 cm at 1% weight of cement. Results indicate that the uses of steel fibers don't have a specific effect on compressive strength of concrete but it has a significant increase in its tensile strength and toughness. Also by increasing the aspect ratio of fiber slump will resistance, and reduces crack expansion.Keywords: fiber reinforced concrete, steel fibersbe decreased. Steel fibers will improve impact

fiber reinforced concrete, steel fibers, toughness, aspect ratio