Fatigue stress represents a critical factor in the progressive deterioration of reinforced concrete (RC) structures, particularly under conditions involving repeated loading and corrosive environments. The synergistic interaction between fatigue and corrosion, commonly referred to as corrosion-fatigue, significantly intensifies the degradation of structural materials, thereby diminishing overall structural integrity and long-term durability.
Fatigue stress originates from the application of cyclic loads, which may be substantially lower than the material’s ultimate strength. Despite their relatively low magnitude, these repeated loads induce the initiation and propagation of micro-cracks over time, eventually culminating in structural failure (Cano, 2012). Corrosive processes further exacerbate fatigue-induced damage by compromising the passive protective oxide layer on reinforcing steel, thus increasing its vulnerability to cyclic stresses. This combined deterioration mechanism, described as corrosion-fatigue, accelerates the loss of mechanical performance in RC components (Devendiran & Banerjee, 2023). Contributing factors such as insufficient concrete cover and prolonged exposure to aggressive environmental conditions further compound the effects of fatigue and corrosion, leading to the premature degradation of RC infrastructure (Cano, 2012).
Mechanism of fatigue in concrete
The fatigue behavior of concrete is influenced by both its intrinsic material composition and various external environmental factors. Notably, the inclusion of fibers within the concrete matrix has been shown to enhance its fatigue resistance by improving crack-bridging capacity and distributing stresses more evenly under cyclic loading conditions (Vicente et al., 2016). External conditions, such as elevated moisture content and prolonged exposure to marine environments, can further affect fatigue performance by altering the microstructural integrity of the concrete (Klausen & Øverli, 2023).
Under repeated loading, concrete undergoes the gradual accumulation of microcracks within its matrix. These microcracks contribute to progressive structural degradation, manifesting as increased permanent (plastic) strains and a notable reduction in stiffness (Zanuy et al., 2009). A significant component of this fatigue damage is the development of irreversible or residual strains, which are primarily associated with mode-II cracking and frictional sliding along crack interfaces (Shan et al., 2019).
A key analytical tool in assessing fatigue behavior is the stress-cyclic number (S-N) curve, which characterizes the relationship between applied stress levels and the number of cycles to failure. Advances in diagnostic technologies, such as X-ray computed tomography (CT) scanning, now allow for real-time monitoring of internal damage processes, including deformation patterns and crack propagation, thereby providing deeper insight into the fatigue life of concrete materials (Fan & Sun, 2021).
Fatigue stress and long term deterioration
Fatigue-induced damage plays a critical role in the long-term degradation of reinforced concrete (RC) structures. Repeated cyclic loading leads to a progressive reduction in both compressive strength and modulus of elasticity of concrete, thereby undermining the structural stiffness and load-bearing capacity over time (Li et al., 2022). This gradual deterioration poses significant challenges to the safety and serviceability of RC infrastructure, especially under sustained operational demands.
The interaction between fatigue and corrosion further amplifies structural vulnerability, particularly in seismic zones. Research has shown that corrosion-fatigue not only accelerates material degradation but also heightens seismic risk. For example, in comparative analyses of RC bridges, three-span configurations exhibited a greater decline in structural resilience over time than two-span counterparts. This increased vulnerability is attributed to the higher flexibility and fatigue sensitivity inherent in more complex bridge geometries (Devendiran & Banerjee, 2023).
To address these concerns, advanced numerical modeling techniques have been developed to simulate fatigue behavior in RC structures. These models are instrumental in predicting structural lifespan by characterizing the relationship between stress amplitudes and the number of load cycles leading to failure (Chai et al., 2016). Such tools not only improve our understanding of fatigue mechanisms but also support the design of more durable and resilient infrastructure.
References
- Wu, W., He, X., Alam, M. S., Zhang, R., Han, T., Shi, X., & He, J. (2023). Effect of high-stress level loads on the fatigue performance of GFRP-RC beams. Composites Part C: Open Access. https://doi.org/10.1016/j.jcomc.2023.100399
- Chai, H. K., Chai, H. K., Onishi, H., Onishi, H., Matsui, S., & Matsui, S. (2016). Evaluating Fatigue Resistance of FRP-Strengthened RC Bridge Decks Subjected to Repeated Wheel Load (pp. 1-12). Springer, Singapore. https://doi.org/10.1007/978-981-10-4508-0_1
- Li, J., Hao, Y., Liu, C., & Xiao, D. (2022). Numerical study of the effect of fatigue on impact performance of RC beams. Science China-Technological Sciences, 66(2), 346-362. https://doi.org/10.1007/s11431-022-2189-9
- Devendiran, D. K., & Banerjee, S. (2023). Influence of Combined Corrosion-Fatigue Deterioration on Life-Cycle Resilience of RC Bridges. Journal of Bridge Engineering, 28(5). https://doi.org/10.1061/jbenf2.beeng-5708
- García Cano, J. (2012). Estudio sobre el estado límite a fatiga en estructuras de hormigón con deterioro de las armaduras. https://upcommons.upc.edu/handle/2099.1/17181
- Klausen, A. B. E., & Øverli, J. A. (2023). A Review on Fatigue Performance of Concrete Structures Part II, Material Parameters and Environmental Factors. 68, 127-144. https://doi.org/10.2478/ncr-2023-0005
- Vicente, M., Mínguez, J., Martínez Martínez, J. A., & González, D. C. (2016). High-Performance Concrete and Fiber-Reinforced High- Performance Concrete under Fatigue Efforts. InTech. https://doi.org/10.5772/64387
- Fan, Z., & Sun, Y. (2021). A Study on Fatigue Behaviors of Concrete under Uniaxial Compression: Testing, Analysis, and Simulation. Journal of Testing and Evaluation, 49(1), 160-175. https://doi.org/10.1520/JTE20190900
- Shan, Z., Yu, Z., Li, X., Lv, X., & Liao, Z. (2019). A Damage Model for Concrete under Fatigue Loading. Applied Sciences, 9(13), 2768. https://doi.org/10.3390/APP9132768
- Zanuy, C., Albajar, L., & de la Fuente, P. (2009). Sectional Analysis of Concrete Structures under Fatigue Loading. Aci Structural Journal, 106(5), 667-677. https://doi.org/10.14359/51663107
