| Base on the problem of large quantity fatigue loads on corroded R.C. structure and small quantity study of its mechanical property, bending resistance fatigue test of corroded R.C. beams is discussed in this paper. The influence of stress ratio and re-bar weight loss ratio on bending resistance fatigue performance of corroded R.C. beams are researched, and the relation between strains of corroded re-bars and fatigue life of beams are obtained. The main research contents and conclusions are as following:1. Under the fatigue loads, the overstrain of concrete approximately coincidences three stages strain development and accumulation rule, and the mechanical property of concrete is deteriorated. The fatigue damage of concrete is accumulated. The overstrain of re-bars increases and the increase rate decreases. The mechanical property of corroded re-bars is deteriorated, and the fatigue damage of re-bars is accumulated.2. The relation between stress ratio and span centre deflection is linear, and when the stress ratio is large, the increase of mid-span deflection by cycle index is small. The smaller the stress ratio is, the larger the increase of span centre deflection by cycle index is. The influence of stress ratio on maximum crack width of specimens is obvious, and the larger the stress ratio is, the longer the fatigue life is, it can influence the mechanical property of specimens directly.3. The mid-span deflection of slight corrosion specimens is smaller than that of non-corrosion specimens on the static loads and the fatigue loads; the maximum crack width of slight corrosion specimens is larger than that of non-corrosion specimens; fatigue life of slight corrosion specimens is shorter than that of non-corrosion specimens; the corrosion of re-bars is a sensitive factor to fatigue life.4. The relation between re-bars strainsεand cycle index N is obvious. The larger theεis, the shorter the N is, and the relation of them is inverse ratio.
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