Research Of The Fatigue Performance Of RC Beams Externally Prestressed With FRP Tendons

Because of the good performance of ultimate strength, corrosion-proof and fatigue durability of the FRP bars, they are becoming more and more widely used in the civil engineer area. It is necessary to study the fatigue performance of RC beams Externally Prestressed with FRP Tendons.It was accentuated about the evaluation of the fatigue performance RC beams externally prestressed with FRP tendons, while the three key evaluating factors were analyzed consisting of the structure failure criteria , fatigue-life prediction and the attenuation of flextural stiffness.This dissertation studied the recent material fatgue experiments and associated theory. Much work are accomplished about the theory of the fatigue-life prediction and the fatigue accumulated damage models thus helped to analyze the structural integer fatigue accumulated damage .With the help of the fiber-optical technologies (BOTDR and FBG) ,experiments of the concrete beams externally prestressed with AFRP tendons were carried out under 2-millions-dynamic cycles to study the variance of the stress and strain of the structure while the dynamic inspection was conduted.A simplified model was introduced to analyse the flextural performance of the beams prestressed with external tendons under various loads, with the induction of the fatigue accumulated damange materials models based on which the computer program about the structural fatigue accumulated damage analysis was composed. The fatigue performance of RC beams externally prestressed respectively with CFRP bars, AFRP bars, GFRP bars, and steel bars were compared numerically to evaluate the influence of the spieces of the external tendons to the structural fatigue performance. Finally designing key points and suggestion about the structures under fatigue loads were presented.According to all the above researches of experiment and theoretical analysis, this kind of structures perform well in anchorage , fatigue proof and wearance, that will make them quite valuable in the appliance and most prospective in the future.