Fatigue damage analysis of corroded prestressed concrete beams using acoustic emission

Reinforced concrete (RC) beams are susceptible to corrosion under environmental and service conditions, compromising structural safety. This study focuses on prestressed RC beams with localised corrosion, using acoustic emission (AE) techniques to monitor the four-point bending fatigue tests. Damage in different beam regions is analysed through load ratios and AE parameters. A relative damage index is proposed to compare fatigue damage variations between corroded and non-corroded regions, exploring the impact of corrosion on the beams. A margin index is used to assess the damage stages and analyse damage evolution. The results indicate that the corrosion effect is mainly concentrated in the initial quarter of the beam’s service life. The fatigue damage process can be divided into corrosion-dominated and fatigue-dominated stages according to the relative damage index. The margin index effectively reflects the beam’s damage evolution and, in conjunction with AE parameters, provides a clearer assessment of its damage state. This study provides a methodological basis for the assessment of fatigue damage in corroded RC beams, thereby facilitating the formulation of more targeted maintenance strategies and the evaluation of residual service life for engineering structures such as bridge and marine infrastructures to ensure service safety.