预应力与非预应力AFRP加固腐蚀钢筋混凝土梁疲劳性能研究

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K f。结果表明,钢筋锈蚀率的增加会导致K f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。

Study on fatigue performance of prestressed and non-prestressed AFRP reinforced corroded reinforced concrete beams

The fatigue properties of corroded reinforced concrete beams reinforced with non-prestressed arylon fabric (AFRP) and prestressed AFRP with permanent anchorage are studied. Through fatigue test, the influence of prestress level and steel corrosion degree on fatigue failure mechanism, fatigue life and deflection of reinforced beams is discussed. The test results show that the fatigue failure mechanism of prestressed AFRP and non-prestressed reinforced beams is the same, and both are fatigue fracture of longitudinal reinforcement. The fatigue resistance of prestressed AFRP reinforced corroded concrete beams is obviously better than that of non-prestressed reinforced beams. The higher the prestress level, the higher the fatigue life of moderately corroded beams after reinforcement; The higher the corrosion rate, the lower the fatigue life of the beam, and the reduction of fatigue life of the severely corroded beam is more obvious than that of the moderately corroded beam. The equivalent fatigue notch coefficient Kf of the corroded longitudinal bar is obtained by comparing it with the plain steel bar. The results show that the fatigue life of corroded beams decreases obviously with the increase of steel bar corrosion rate. Based on the test results, a formula for calculating fatigue life of moderately corroded reinforced concrete beams reinforced by prestressed AFRP is established, which can be used as a reference for bridge reinforcement design.