Numerical Analysis of the Fatigue of Steel Fiber Reinforced Concrete Beams Using ANSYS Workbench Simulation

Abstract

Aims: The primary aim of this study was to evaluate the fatigue behavior of Steel Fiber Reinforced Concrete (SFRC) beams subjected to cyclic loading. Specifically, this study investigates the influence of fiber content on the fatigue performance of concrete beams using numerical simulations in ANSYS Workbench. Study Design: The study employed a computational approach using the Finite Element Method (FEM) to model SFRC beams with varying fiber contents. The models were analyzed under cyclic loading conditions to assess the fatigue life and stress distribution across the beams. Methodology: Three finite element models of steel fiber–reinforced concrete (SFRC) beams were simulated, corresponding to steel fiber volume fractions of 0.0% (plain concrete), 1.0%, and 1.5%. The analyses were performed in ANSYS Workbench, where the concrete matrix was modeled using SOLID186 elements, and the steel fibers were represented by LINK180 elements embedded within the beam volume. A zero-based cyclic four-point bending load corresponding to 60% of the static ultimate load was applied, with supports and loading points defined as simple supports and concentrated loads, respectively. Fatigue life assessment was conducted using the S–N curve approach for both materials, combined with the Goodman mean-stress correction to account for multiaxial stress effects. The fatigue tool in ANSYS was used to evaluate stress distribution, damage progression, and fatigue sensitivity for each fiber content case. Results: The results showed that increasing the fiber content improved the fatigue life and delayed failure. The model with 1.0% fiber content demonstrated the best balance between durability and numerical stability, while higher fiber content (1.5%) resulted in a marginally higher fatigue safety factor but increased computational instability. Specifically, the fatigue safety factor (FS) increased from 50.6% for plain concrete to 53.1% for 1.0% fiber and 56.6% for 1.5% fiber, representing an enhancement of up to 6.0 percentage points. The predicted fatigue life for all models remained within the range of 10⁶ cycles, However, the presence of fibers resulted in a slower stiffness degradation rate and a reduction in maximum cyclic deflection of approximately 12–15% compared to the control beam. Conclusion: The study confirms the beneficial role of steel fibers in improving the fatigue performance of concrete beams. These findings highlight the importance of optimizing fiber dosage in the structural design of SFRC elements to achieve greater service life and resilience under cyclic loading. The outcomes can guide performance-based design strategies and material selection in infrastructure exposed to repeated stress conditions, promoting more durable and sustainable concrete structures.