Flexural behavior of reinforced concrete beams subjected to natural corrosion in marine environment

This paper presents an experimental investigation and analytical estimation of 26-year-old naturally corroded reinforced concrete (RC) beams in a marine environment. The flexural performance of eight beams was evaluated through four-point and three-point bending tests. Corroded steel bars were extracted after loading test to construct geometric morphologies and to determine the corrosion degree using 3D laser scanning technique. Experimental results indicated that reinforcement corrosion in a natural environment exhibited significant longitudinal non-uniformity, generally following a pattern of being more severe at mid-span and less severe towards the ends. The non-uniform corrosion along the longitudinal direction of the reinforcement might lead to the failure occurring at non-critical cross-sections of the specimen. Additionally, the difference in corrosion among different longitudinal reinforcements could result in premature fracture of severely corroded rebars, causing stress redistribution among the remaining rebars. Consequently, a multi-stage characteristic was observed in load-deflection curves and the cross-section where failure occurs may shift to a new location. Thereafter, the calculation results using a simplified failure mode-based method for bending bearing capacity of normal cross-section of RC beams matched well with the test results. This work contributes to a deeper understanding of the degradation mechanisms of naturally corroded RC beams and provides valuable insights for the design and maintenance of coastal and marine infrastructures.