Multiple Time‐Scale Homogenization of Coupled Corrosion‐Fatigue in Structural Concrete

ABSTRACT Reinforced concrete structures exposed to chloride‐rich environments and cyclic mechanical loading experience simultaneous corrosion of steel reinforcement and fatigue‐induced concrete cracking, leading to complex, nonlinear degradation that cannot be accurately captured by conventional sequential analyses. This work presents a fully coupled multiphysics phase‐field framework based on a multiple time‐scale homogenization strategy, which models the co‐evolution of corrosion, chloride transport, fatigue damage, and fracture in both concrete and steel, explicitly capturing the mutual interactions between chemical and mechanical degradation across distinct temporal scales. Unlike traditional approaches, the model resolves feedback mechanisms in which corrosion accelerates fatigue by weakening the steel‐concrete interface and inducing microcracks, while cyclic loading enhances chloride ingress and promotes corrosion progression, effects that are difficult to observe experimentally. Numerical studies, including two‐dimensional simulations of representative rebar configurations and a three‐dimensional beam structure, demonstrate how the homogenized treatment of fast fatigue cycles and slow corrosion processes enables efficient and consistent prediction of degradation, and how the timing, rate, and sequence of cyclic loading relative to corrosion govern crack initiation, corrosion kinetics, and fatigue lifetime. Results show that conventional corrosion‐followed‐by‐fatigue approaches systematically underestimate service life, whereas the proposed multiple time‐scale, fully coupled framework provides accurate, physics‐based predictions of degradation. This highlights the critical importance of modeling corrosion and fatigue as mutually interacting processes within a unified time‐scale homogenization framework and offers new insights into the spatio‐temporal interplay between cracking, transport, and corrosion in structural concrete.