Numerical and experimental investigations on stress redistributions of fatigue loaded concrete structures in the very high-cycle fatigue range
Construction Material Sciences, Chemistry, Building Physics
Final Report Abstract
The expansion of renewable energies, especially wind energy, is a key element in reducing CO2 emissions. Research is needed for resource-efficient manufacturing of tower structures. For hub heights exceeding 100 meters, hybrid towers made of prestressed concrete segments are the most suitable construction. However, precise knowledge of the fatigue behavior of concrete is required for this purpose. Existing literature predominantly focuses on small-scale cylindrical specimens, but the results of which have limited applicability to large-scale components. In this project, large-scale tests on cyclically flexural loaded, prestressed concrete beams were conducted, along with accompanying experiments on small-scale cylindrical specimens, and numerical simulations of the beam tests. The numerical material model was developed based on an additive strain model within the finite element software ANSYS Mechanical, implemented in an iterative calculation process. Concrete strains in this model are composed of four components: elastic, plastic, viscous, and temperature-induced strains. Thus, the combined influence of these components on the fatigue behavior of concrete was investigated. In the large-scale tests, fatigue failure was induced in the beam specimens, characterized by the development of cracks parallel to the compressive normal stress and partial spalling of the concrete compression zone, which was subjected to the highest stress cycle range. It was observed that this occurred after significantly more load cycles than in the accompanying cyclic tests on axially loaded concrete cylinders with the same stress cycle range. This can be attributed to stress redistribution that occurred within the cross-section due to fatigue-induced material degradation and stiffness reduction in the highly stressed edge regions. In the accompanying tests, material parameters for the numerical model were determined, which were subsequently used to simulate the beam tests. The model successfully replicated the observed effects of stiffness degradation, stress redistribution, and the resulting extension of the fatigue life. Thus, the model can be used for further investigations into the service life of fatigue-loaded concrete components.
Publications
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Große Betonbalken in Resonanz. Jahresbericht 2020, Institut für Massivbau, Technische Universität Dresden, S. 78–79.
Birkner, Dennis
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Positive Effekte durch Ermüdung?. Jahresbericht 2021, Institut für Massivbau, Technische Universität Dresden, S. 50–51.
Birkner, Dennis
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Lebensdaueruntersuchungen in kurzen Zeiträumen. Jahresbericht 2022, Institut für Massivbau, Technische Universität Dresden, S. 40–41.
Birkner, Dennis
