Rybczynski, SebastianSebastianRybczynskiSchmidt-Döhl, FrankFrankSchmidt-DöhlSchaan, GunnarGunnarSchaanRitter, MartinMartinRitterDosta, MaksymMaksymDosta2023-01-232023-01-232022-098th International Conference on Structural Engineering, Mechanics and Computation (SEMC 2022): 1322-1326978-1-003-34844-3978-1-000-82436-0978-1-000-82432-2978-1-032-18698-6http://hdl.handle.net/11420/14612This contribution deals with experimental and numerical results on the fatigue behavior of Ultra-High Performance Concrete (UHPC). In order to characterize fatigue-induced changes in detail, UHPC samples were examined using scanning and transmission electron microscopy (SEM and TEM). It could be shown that a densification of the binder matrix occurs caused by a transformation of nanoscale ettringite, and the content of unhydrated cement clinker influences the fatigue resistance of UHPC. For numerical investigations of the mechanical behavior of UHPC, the Bonded-Particle Model (BPM) has been used and calibrated with experimental data. The mesoscopic BPM model consists of three phases: Matrix, ITZ (Interfacial Transition Zone), and aggregate. A newly derived rheological fatigue formulation for binder and ITZ bonds was developed to apply small scale-changes and plastic deformations to reproduce the correct fatigue behavior.enTechnology::600: TechnologyConference Paper10.1201/9781003348443-215Conference Paper