| Steel bars corrosion is one of the most important factors that influence durability of reinforced concrete structures or members. Corroded bars (especially with unsymmetrical corrosion pits) under fatigue loads not only make deterioration of its own behavior but also the bond performance between bars and concrete of reinforced concrete members. Based on full analysis of research results over the world, this paper conducts three parts of study on fatigue durability problems of reinforced concrete: first, experimental and theoretic study on both not corroded and corroded (with corrosion pits) bars under fatigue loads has been conducted; second, experimental and theoretic study on the bond behavior between corroded bars and concrete under fatigue loads has been done; third, reliability of R.C. members with corrosion pits on bars has been set up used to evaluate the fatigue expectation of bars with local corrosion pits.First, experimental research on remained static strength of both not corroded and corroded bars with local pits under fatigue loads has been done. On the base of experimental data, a new fatigue limit measuring method of steel bar in concrete based on remained strength has been presented; influence on remained static strength of corrosion amount and the two-dimension size of corroded pits has been analyzed; deterioration law of parameter C in S-N curve has been gotten; based on experimental results, experience and the qualities of local pits in steel bars, this paper has set up a two-dimension mode used to describe the shape of corrosion pits(in the past, only the corrosion depth (one dimension)of bars had been studied mainly), according to the procedure of corrosion and the principle of electricity-chemistry, formula of the two-dimension sizes have been set up; the stress intensity factors calculating method of local corrosion pits under fatigue loads has been studied according to qualities of corroded bars and fracture mechanics.
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