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 through-crack 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.