预应力芳纶纤维布加固腐蚀混凝土梁疲劳性能
Fatigue Performance of Corroded RC Beams Strengthened With Prestressed AFRP Sheets
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摘要: 对带永久锚具的预应力芳纶纤维(AFRP)布加固锈蚀钢筋混凝土梁的疲劳性能进行了试验与研究.通过疲劳试验,探讨了预应力水平和钢筋锈蚀程度(中度6%、重度12%)对加固梁疲劳破坏机制、疲劳寿命、挠度和应变发展等疲劳特性的影响.试验结果表明:预应力AFRP布与非预应力AFRP布加固梁的疲劳破坏机制相同,都为钢筋的疲劳断裂;预应力AFRP布加固锈蚀钢筋混凝土梁的抗疲劳特性明显优于非预应力AFRP布加固梁,且AFRP布预应力水平越高,加固梁的疲劳寿命越高;锈蚀率越高,梁的疲劳寿命越低,重度锈蚀梁的疲劳性能的降低幅度比中度锈蚀梁更明显;钢筋锈蚀率的增加会导致钢筋的等效疲劳切口系数增大,从而导致锈蚀梁疲劳寿命的显著降低.Abstract: A primary study on fatigue behaviors of strengthening corroded RC beams using prestressed aramid fiber reinforced polymer(AFRP) sheets with permanent anchor was carried out.The objective is to examine the effects of AFRP composite rehabilitation systems on the fatigue performance of corroded RC beams.Based on the fatigue experimental results,the effects of different pre-stress level of AFRP sheets under different ratio of corrosion(moderate corroded:reinforcement mass loss is 6.0%,severe corroded:reinforcement mass loss is 12%) on the properties of the fatigue failure, fatigue life, mid-span deflection and materials strain were analyzed. The experimental results showed that, the fatigue failure mechanism of the corroded RC beams strengthened with AFRP sheets is the fatigue fracture of steel bar. Comparison between the beams strengthened with prestressed AFRP sheets and the beams with non-prestressed AFRP sheets was made, and it shows that the fatigue life of the retrofit RC beams increased with increase of the pre-stress level of AFRP sheets and the fatigue life of the corroded RC beams decrease with increase of the ratio of corrosion. Pitting corrosion resulted in the increase in the fatigue notch factor, and this increase resulted in a significant reduction in the fatigue life.