纤维束编织网增强混凝土加固钢筋混凝土梁疲劳破坏试验研究

Experimental study on fatigue failure of RC beam reinforced with textile reinforced concrete

为研究纤维束编织网增强混凝土加固钢筋混凝土梁的疲劳性能,首先制作10根钢筋混凝土梁试件,并对其中的9根用纤维束编织网增强混凝土进行加固,1根作为对比梁未进行加固,然后采用三分点弯曲加载对试件施加疲劳荷载。试验研究了加固方式、配网率、配筋率、损伤程度等4个因素对加固梁的疲劳裂缝扩展及变形发展的影响。试验结果发现:纤维束编织网增强混凝土加固可以显著提高RC梁的受弯疲劳寿命。加固梁的裂缝数量多于非加固梁,裂缝宽度小于非加固梁。在疲劳荷载作用下,加固梁的裂缝及挠度发展都呈现初始发展、稳定发展、迅速发展三个阶段。针对加固形式,三面加固对斜裂缝的控制优于单面加固。加固前的静力损伤会影响加固梁的裂缝宽度,静力损伤越大,疲劳加载时的裂缝宽度越宽。配网率会影响加固梁最终破坏时的挠度,当配网率大于某一值时,加固梁最后破坏时的挠度明显增加;配筋率的增加可以延长挠度的稳定发展阶段。最后通过回归分析,得到了加固梁的疲劳刚度的算式,由该式计算的结果与试验结果符合良好,可为工程使用提供理论依据。

In order to study the fatigue properties of RC beams reinforced with TRC,ten RC beams were made at first.And nine beams among them were strengthened with TRC; one beam wasn't strengthened as comparison. Then,threepoint bending loading of fatigue test was utilized to study the influence of reinforcement form,percentage of textile reinforcement,reinforcement ratio and damage degree of beams on cracks and deformation development. The results show that the fatigue life of RC beams can be significantly improved by TRC. The reinforced beams have obvious better performance than unreinforced beams in controlling the number and the width of cracks. Under fatigue load,the cracks and deflection development of reinforced beams shows three stages: the beginning development stage, stable development stage and rapid development stage. In terms of reinforcement form,the three-sided reinforcement has better ability than one-sided reinforcement in controlling diagonal cracks. The damage of static loading before reinforcing can affect the development of cracks,the more the damage of static loading is,the more width the cracks are. The percentage of textile reinforcement has influence on the ultimate deflection of beams,when it reaches a certain value,the deflection of beams is significantly increased. The increase of reinforcement ratio can extend the second stage of the deflection. At last,the fatigue stiffness of reinforcement beams are deduced through regression analysis. The value calculated via this formula has a high accuracy degree with experimental value. Therefore,it can provide a theoretical basis for engineering use.