Extension and verification of an energetic fatigue model for concrete under dynamic compressive loading

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Structures for wind turbines as well as railway or highway bridges are high-dynamically stressed. The dynamic stresses are leading in concrete, as well as in other materials, to deformation and damage processes, which can end in the collapse of the structure. These deformation and damage processes are called in general as material fatigue.Although the main part of the above mentioned structures are built out of concrete no consistent model to describe the occurring deformation and damage processes in concrete under cyclic loading exists. In literature published material models are neither sufficiently validated nor consider the influence of concrete creep, which occurs inevitably in parallel with the cyclic stresses.The submitted research project aims to expand an existing fatigue model for concrete, which is taken from literature. It is considered to be one of the most promising models for describing concrete fatigue. The extension consists in particular the acquisition of concrete creep. Therefore extensive experiments will be performed on small-scale concrete specimens to separate the deformation and damage processes resulting of cyclic loading from creep deformation processes. In addition, a creep-relevant stress levels will be determined as a function of the cyclic stress values.The extended fatigue model will conclusively verified in the course of systematically coordinated experimental programs on the basis of the experimental results. In future this should give the opportunity to depict the fatigue processes of concrete beams or structures by keeping fatigue and creep processes into consideration. The resulting model enables to consider stress redistributions in cyclically loaded concrete structures and components and to utilize unused system resources.