Combined fatigue-corrosion damage in reinforced concrete: Experimental analysis, surface crack monitoring, and mechanical modeling

Reinforced concrete (RC) is widely used in civil infrastructure; however, its durability is severely compromised by the combined effects of fatigue loading and steel corrosion. This study comprehensively investigates the degradation mechanisms of RC bridge specimens subjected to coupled fatigue-corrosion loading. A three-phase experimental program was designed, incorporating cyclic loading under controlled accelerated corrosion conditions. Mechanical performance and surface damage were monitored using high-resolution imaging and multi-source sensing systems. Experimental results reveal that fatigue loading primarily promotes longitudinal crack development along principal shear paths, whereas corrosion significantly increases crack density and propagation by weakening material cohesion and inducing microcracking. Furthermore, a meso-scale plastic damage model for concrete was developed to describe the fatigue-induced deterioration process, while electrochemical corrosion mechanisms of the steel reinforcement were modeled simultaneously. This integrated approach combining imaging-based crack monitoring with coupled fatigue-corrosion modelling enables a deeper understanding of RC damage progression. The results provide new insights and practical guidance for durability assessment and predictive maintenance of RC structures. • Combined fatigue-corrosion effects were tested in multiple stages. • Integrated mechanical and image series for full-cycle damage propagation. • Mechanical behavior modeled and verified by simulation.