ABSTRACT
This paper presents a thermodynamically-based lattice discrete particle model (LDPM) for simulating concrete fatigue from material to structural scale. The constitutive model is rigorously derived from thermodynamic potentials with explicit damage evolution driven by cumulative plastic strain at inter-aggregate level. The model is calibrated through comprehensive uniaxial compression simulations on prisms, accurately reproducing S-N curves, Sparks-Menzies relations, and realistic hysteretic behavior. At the structural level, the model predicts progressive damage evolution and stress redistribution in prestressed beams under subcritical cyclic loading. Key findings include: (i) the perfect alignment of material-to-structural fatigue results with the Sparks-Menzies relation provides theoretical justification for extrapolating laboratory fatigue relationships to engineering applications; (ii) damage dissipation emerges as a scale-invariant fundamental material property, offering a physically grounded alternative to empirical design approaches. The presented thermodynamic framework enables structural fatigue prediction based on material-level calibration, reducing reliance on costly full-scale testing while providing insights into concrete fatigue mechanisms.
