Numerical and experimental investigations on stress redistributions of fatigue loaded concrete structures in the very high-cycle fatigue range

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Concrete has a complex deformation behavior under fatigue loads. This behavior influences the stress distribution on the cross-sectional level of concrete structures and has a positive effect on their service life. The normative fatigue analysis concept is based on S-N-curves. The deformations of the concrete and the resulting stress redistribution at the cross-sectional level are almost neglected, whereby fatigue-stressed concrete structures are not economically determined according to the current design concept.The aim of this research project is to investigate the deformation behavior and in particular the stress redistribution of fatigue loaded concrete structures. Within this framework, FE-simulations as well as experimental tests are conducted. The simulations are based on a strain model for fatigue-loaded concrete developed at the Institute for Concrete Construction of Leibniz University Hannover. The experimental investigations are carried out on the resonance fatigue testing stand of the institute. This worldwide unique testing stand allows the examination of concrete beams in the very high cycle fatigue range, i.e. more than 1 • 10^7 load cycles. This is essential for the experimental investigations, since the stress redistributions cause very high, sustainable load cycles in the concrete beams.The numerical simulations are verified by the experimental investigations. On this basis, general statements can be made regarding the deformation behavior and the stress redistribution of fatigue-loaded concrete structures as well as the formulation of new design proposals. The results of this research project serve the design of highly fatigue loaded structures such as wind turbines or high-speed railway bridges. They make it possible to move towards a more realistic dimensioning and thus a more economical and cost-effective design of fatigue loaded concrete structures.