Experimental Investigation of High-Cycle Compressive Fatigue Performance of C80 High-Strength Concrete

With the height of wind turbine towers increasing, the high-cycle fatigue performance of high-strength concrete has become important for structural design. This study systematically investigates the fatigue life, strain evolution, and stiffness degradation of C80 concrete under constant-amplitude cyclic compressive loading for a maximum stress level ranging from 0.70 to 0.90 and a minimum stress level of 0.10. Based on experimental data, <i>S-N</i> curves are obtained, and a prediction model of fatigue life and stiffness degradation is developed. The results reveal that fatigue strain evolves through three stages and that the second stage accounts for more than 90% of the overall fatigue life, exhibiting linear growth over time. The final strain in the second stage is very close to that in static compression tests, indicating the uniqueness of fatigue strain. In addition, the final strain in the second stage provides a better prediction of fatigue life than an <i>S-N</i> curve and facilitates real-time fatigue life prediction. Meanwhile, the stiffness degradation model more accurately simulates the stiffness degradation process of C80 concrete under fatigue load, laying a foundation for further finite element analysis of fatigue. This study addresses the gap in fatigue life prediction and stiffness degradation modeling for C80 concrete under high-cycle fatigue load, providing a valuable reference for designing safe and durable high-strength concrete structures such as wind turbine towers.