Numerical prediction for life of damaged concrete under the action of fatigue loads

High-speed railways have become a critical component of modern transportation, and ensuring the stability and durability of high-speed railway concrete under environmental and train fatigue loads is essential for ensuring project safety. This paper employs a numerical simulation method to predict the performance and lifespan of high-speed railroad concrete under fatigue loading with environmental damage. The study analyzes the effects of stress level (0.5 ∼ 0.8), stress ratio (0.1 ∼ 0.9), and load frequency (5 Hz ∼ 40 Hz) on the fatigue performance and lifespan of railway concrete during bending fatigue loading. A four-point bending numerical model of concrete is developed in this paper, which considers elastic modulus decay and surface cracking, in order to quantify the degradation of concrete properties in response to environmental and load-induced cracks. The numerical model is well-validated with experimental results, and the study establishes a correlation between concrete degradation and environmental and load-induced cracks, as well as the fatigue resistance of high-speed railroad concrete. The bending fatigue frequency of concrete should not exceed 25 Hz at high stress levels of 0.7. This study also shows that environment-induced initial damage will greatly reduce the fatigue resistance of concrete, and fatigue life degradation and elastic modulus decay have a nearly linear relationship. This research provides a crucial foundation for the fatigue design of concrete materials for high-speed railroads.