A Fatigue Experimental Investigation On Reinforced Concrete Beams With Corroded Main Bars

The static behavior of corroded RC structures has been widely investigated but the research on the dynamic particularly the fatigue properties is quite few at home and abroad.In this study the fatigue experiment under the same loading and measuring system was carried out on nine pieces of reinforced concrete beams and the fatigue properties data of the beams were obtained. All specimens were composed of one control beam (without main bars corrosion) and eight pieces of corroded main bars beams (with corrosion rate from 4% to 12%). It showed that the accelerating corrosion effect by the accelerating corrosion means in this study was similar to the corrosion effect in real structure. The corrosion rate of main bars is the only varying factor considered in this experiment. Vibration test was done on the beams under different state. Main bars of all the specimens were taken out for static tensile experiment after fatigue experiments. It showed that the vibration test cannot predict the fatigue failure of the fatigued beams effectively. It can be seen from the results that the control beam had good plastic property in the static failure experiment after two million fatigue loading circles. All specimens with corroded main bars were failure under the fatigue loads within one million fatigue circles. Fatigue lifespan of reinforced concrete beam was sharply shortened after main bars corroded in it and the beam was destroyed bristly without any prediction. The results of the static tensile experiments showed that the static property of the main bars was greatly changed after fatigue load effect which also changed the mechanics property of corroded reinforcement concrete beams. The analysis on all aspects showed that the mechanics property of the corroded reinforcement concrete beams was affected by main bar corrosion rate and the number of fatigue circles. The modified fatigue stiffness calculation of corroded reinforcement concrete beams was introduced in this study. Based on the linear fatigue cumulating damnification theory, the calculation of fatigue cumulating damnification intensity was also modified with main bar corrosion rate, which is the most important factor for fatigue lifespan of reinforced concrete beams. Investigations of corroded reinforcement concrete structures could obtain some support from this experiment in the future.