Numerical study on fatigue failure mechanism of reinforced concrete slabs under coupled action of corrosion and cyclic loading

Based on three-dimensional scanning technology, a database of real block stone shapes with varying particle sizes was established, and discrete element models of reinforced concrete with different corrosion rates were developed, accounting for the particle crushing effect. Four-point bending fatigue numerical simulations were conducted on reinforced concrete models with corrosion rates of 0%, 10%, 25%, and 40% to investigate their mechanical characteristics, failure modes, damage evolution, force chain distribution, and energy dissipation. The aim was to reveal the influence mechanism of corrosion on the fatigue performance of reinforced concrete.The results show that for uncorroded specimens, the stiffness ratio decreases gradually, with a residual stiffness of 60%. At a corrosion rate of 40%, the stiffness ratio exhibits a cliff-like drop, leaving only 30% residual stiffness. Deflection growth is markedly accelerated, and the deformation capacity of the structure deteriorates significantly. In terms of failure mode, corrosion causes a gradual transition from ductile bending failure to brittle shear failure. This shift indicates a substantial reduction in both load-bearing capacity and structural safety margin. Damage process analysis reveals that acoustic emission intensity progresses through three stages: micro-crack initiation, stable crack propagation, and rapid crack expansion leading to structural instability. Corrosion accelerates both the initiation and propagation of micro-cracks, causing rapid accumulation and coalescence of internal damage. This process is accompanied by the absorption and release of strain energy, with the peak strain energy of highly corroded specimens decreasing by more than 80%. Regarding force chain distribution, uncorroded specimens have 25% of their force-chains classified as strong, forming an optimal load-transfer path oriented at approximately 45°. As the corrosion rate increases, the proportion of strong force-chains gradually declines.