Mechanical Resistance of Steel Fiber Reinforced Concrete to Axial Load

New experimental data make it possible to start with the synthesis of a steel fiber reinforced concrete (SFRC) load resistance model. Four stages are considered: the elastic stage, the stage of closed isolated crack development, and the stages of throughcrack development in the absence of fiber ruptures and in their presence. Mathematical expectations of the tensile loads as a function of crack growth or of strains are found. Numerical experiments were carried out. The main results of these experiments were as follows: (1) Longitudinal resistance of fibers to crack growth reaches a maximum, after which it decreases to zero. (2) Transverse resistance increases monotonically. (3) Bond improvement leads to two opposite effects: an increase in longitudinal resistance and an earlier appearance of fiber ruptures. As a result, the total resistance increases if the crack opening is small and decreases if it is large. (4) Increase in the SFRC strength is larger when the bond is better.