Assessment of Fatigue Life for Corroded Reinforced Concrete Beams under Uniaxial Bending

Abstract

An understanding of how corrosion affects fatigue behavior of reinforced concrete (RC) structures is essential for lifetime-oriented maintenance and design of existing bridges. This paper covers an experimental investigation on fatigue behavior of corroded RC beams. Corrosion in six RC beams was artificially accelerated by the impressed current method before fatigue loading was administered. All beams failed with fatigue fracturing of their tension steel bars. The fatigue test results indicated that the more severe the corrosion on steel bars was, the sooner the beams failed. The behavior of corroded steel bars determines the fatigue behavior of RC beams. This paper introduces a segmented linear model to simulate nonlinear behavior of corroded RC beams under fatigue loading, which was verified by experimental results. Of particular interest was the deterioration of corroded RC beams under fatigue loading, including the fatigue damage to concrete and corroded steel bars as well as the bond behavior between steel bars and concrete. The proposed model can simulate the development of strains in concrete and steel bars under fatigue loading, thereby permitting a fatigue life assessment. Further analysis investigated the effects of corrosion level, longitudinal variation of the cross-sectional areas, reinforcement ratio, load amplitude, and bond behavior as well. With the increasing degree of corrosion, load amplitude and longitudinal variation of the cross-sectional areas, or the decrease of the reinforcement ratio, the fatigue life of corroded RC beams decreased. The deterioration of bond behavior had little effect on fatigue life, but it led to a reduction in the flexural stiffness of beams.