The effect of reinforcement corrosion on the structural performance of concrete flexural members
Rational decisions about cost-effecctive bridge designs, optimum inspection strategies and repair are hampered by the absence of comprehensive data on the mechanical performance of deteriorated concrete elements. One of the most important causes of concrete deterioration is corrosion of the steel reinforcement. In general corrosion of reinforcement is believed to affect the structural performance of concrete elements in two ways. First, by increasing the stress concentration on the rebar cross section, due to corrosion-induced reduction in the rebar cross-sectional area, which may lead to premature failure if the stresses in the rebar exceeds its yield strength. Second, by weakening the transmission of stresses in the composite resulting from the loss of bond strength between concrete and the steel reinforcement and the growth of cracks due to the formation of corrosion products at concrete/reinforcement interface. As part of a 'Brite Euram' Project, sponsored by the E.E.C., the author has developed procedures for assessing the influence of reinforcement corrosion on the structural performance of reinforced concrete flexural members. The experimental work was carried out on reinforced concrete beams which were subjected to accelerated reinforcement corrosion and then tested in flexure. Corrosion was induced in reinforcement by means of two external power supplies. The results obtained from the experiments show that reinforcement corrosion reduced the stiffness and the load carrying capacity of concrete beams significantly. Structural analysis and reliability analysis techniques were applied to the results of the study, and simple models for predicting the flexural load capacity of corroded beams were produced. The effect of reinforcement corrosion on the bond strength at the steel/concrete interface was also investigated. The results of the study provide evidence to indicate a trend of increased bond strength associated with small degrees of corrosion in reinforcement (≤0.4% reduction in rebar diameter).