Concrete structures may be subjected to very high loads, and these loads affect the behavior and safety of the various structure elements, so a lot of methods and studies were made to develop the design methods for these structure elements, and enhancing its strength. One of these methods, use steel fiber in concrete structure elements mix for strengthening. In this study we chose reinforced concrete beams with steel fiber added to the mix, for enhancing shear and flexural behavior. So, an experimental study was conducted for nine reinforced concrete beams, three specimens were without steel fiber as control beams specimens, one specimen with steel fiber in the full mix, three specimens with steel fiber only in the lower half of each, with different steel reinforcement bars, and, two specimens each of them has steel fiber within one third of each side of the beams. The results such as crack patterns, failure modes, loads deflection curves, steel strains, the stiffness degradation, ductility ratio energy absorption, and stiffness degradation for the beams were studied in this program. Based on this study and analysis of these results, it was found that we can make suggestions to enhance shear and flexural strength for reinforced concrete beams, such as adding steel fiber with percentage = 120 Kg / m3 with Vf = 1.5% at the lower part of beams which has low steel reinforcement ratio to enhance the flexural capacity, or adding steel fiber at 1/3 from each sid