Effect of fatigue loading parameters on the flexural fatigue of steel fiber reinforced concrete beams

This work presents the results of an experimental investigation on the fatigue behavior of Structural Fiber Reinforced Concrete (R/SFRC) beams. By incorporating steel fiber reinforcement, R/SFRC beams exhibit enhanced durability, crack control, ductility, toughness, and strength compared to beams with conventional steel rebars (RC) without fibers. Moreover, the use of steel fibers in a concrete matrix may allow a reduction of steel reinforcement in structural elements. Fatigue tests were performed at a continuous stress level corresponding to 80% of the steel yield strain, with loading frequencies of 6 Hz and 0.35 Hz and stress ratios of 0.3 and 0.1. The results indicate that incorporating steel fibers promotes a more uniform distribution of tensile stresses, thereby enhancing the fatigue life of the beams. Furthermore, lower frequencies intensify mechanical degradation due to increased energy release per cycle. At elevated stress amplitudes, the reduction in stiffness becomes more pronounced, which further compromises fatigue performance.