对非预应力芳纶布(AFRP)加固和带永久锚具的预应力AFRP加固锈蚀钢筋混凝土梁的疲劳性能进行研究.通过疲劳试验,探讨预应力水平和钢筋锈蚀程度对加固梁疲劳破坏机制、疲劳寿命、挠度等的影响.试验结果表明:预应力AFRP与非预应力加固梁的疲劳破坏机制相同,都为纵筋的疲劳断裂;预应力AFRP加固锈蚀混凝土梁的抗疲劳特性明显优于非预应力加固梁;预应力水平越高,中度腐蚀梁加固后疲劳寿命越高;锈蚀率越高,梁的疲劳寿命越低,重度锈蚀梁疲劳寿命的降低幅度比中度锈蚀梁更明显.通过与光面钢筋对比,获得锈蚀纵筋的等效疲劳切口系数Kf.结果表明,钢筋锈蚀率的增加会导致Kf增大,从而导致锈蚀梁疲劳寿命明显降低.基于试验结果,建立了预应力AFRP加固中度腐蚀钢筋混凝土梁疲劳寿命的计算公式,供桥梁加固设计参考.%A study was carried out for the fatigue behavior of corroded RC beams strengthened by non-prestressed aramid fiber reinforced polymer ( AFRP) sheets and prestressed AFRP sheets with permanent anchors. Based on the fatigue test results, the effects of different pre-stress levels of AFRP sheets under different corrosion ratios ( moderately corroded; reinforcement mass loss 6. 0% , severely corroded; reinforcement mass loss 12%) on the properties of the fatigue failure, fatigue life and mid-span deflection were analyzed. The major cause of the fatigue of the corroded RC beams strengthened with AFRP sheets is the fatigue fracture of the steel bars. The fatigue life of the beams strengthened with prestressed AFRP sheets was longer than that of those beams with non-prestressed AFRP sheets. The fatigue life of the moderately corroded RC beams increased with the pre-stress levels of AFRP sheets, and the fatigue life of the corroded RC beams decrease with the ratio of corrosion. The fatigue results were compared to the fatigue data of smooth bars to estimate an equivalent fatigue notch factor for the main reinforcement bars of the tested specimens. Pitting corrosion resulted in an increase in the fatigue notch factor, which in turn resulted in a significant reduction of fatigue life. Based on the experimental results of moderate corroded concrete beams strengthened with AFRP sheets, the fatigue equation was obtained, and this equation can be used in strengthened design for damaged bridge.
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