Conference Agenda

Concrete fatigue controls long-term safety and serviceability, yet prediction is hampered by heterogeneous mesoscale mechanisms (microcracking, frictional sliding, damage accumulation) and their interaction under monotonic, cyclic, and high-cycle loading. We present a unified discrete mesoscale model in which rigid particles (aggregates) interact through vectorial interface laws coupling pressure-sensitive plasticity and damage derived from thermodynamic potentials. Normal response combines compression plasticity with tensile softening damage; tangential response employs coupled damage–plasticity with kinematic hardening, enabling hysteresis, stiffness degradation upon unloading, and fatigue damage growth below peak load. A mild shear–normal damage coupling reflects loss of tensile integrity after extensive sliding. The formulation yields an energy-consistent decomposition (elastic strain energy, plastic work, plastic free energy, damage dissipation) used to interpret fatigue degradation. Validation covers: (i) non-proportional compression–torsion (vertex effect), (ii) biaxial tension/compression, and (iii) notched three-point bending under monotonic, post-peak cyclic, and subcritical fatigue regimes. Simulations reproduce peak loads, unloading stiffness reduction, crack evolution, lifetime trends, and show that plastic dissipation is amplitude-dependent while damage dissipation is nearly amplitude-insensitive and correlates with failure. This supports damage energy as an objective indicator for remaining fatigue life.