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针对钢箱梁顶板与竖向加劲肋焊接接头疲劳细节,选取了3个已有焊趾疲劳裂纹的局部足尺试件作为研究对象,采用CFRP补强法对其中一组试件焊趾裂纹进行修复,其他两组对比试件则在CFRP补强的基础上分别进行钻孔及裂纹焊合处理。修复结束后,采用疲劳试验机进行100 MPa等应力幅疲劳加载,并在试验结束后对试件进行切割,以获取裂纹扩展断面。对试验数据进行处理分析,分别从疲劳裂纹扩展寿命、扩展断面等角度对修复效果进行评价。结果表明:CFRP补强法可显著提高疲劳裂纹的扩展寿命;在CFRP补强的基础上进行钻孔或裂纹焊合处理可进一步降低疲劳裂纹的扩展速率;CFRP布参与工作后可明显降低试件截面的疲劳应力,但粘贴未施加预应力的CFRP布对于短裂纹则几乎没有修复效果。
According to the fatigue details of welded joints between steel box girder roof and vertical stiffener, three local full-scale specimens with fatigue crack of weld toe were selected as the research object. One set of weld toe crack was made by CFRP reinforcement method Repair, the other two groups of comparative specimens are on the basis of CFRP reinforcement drilling and crack welding. After the repairing, the fatigue test machine was used to carry out the fatigue loading of the stress amplitude of 100 MPa. After the test was finished, the test piece was cut to obtain the crack propagation section. The experimental data are analyzed and treated, and the repairing effects are evaluated respectively from the aspects of fatigue crack growth life span and extended section. The results show that the CFRP reinforcement method can significantly increase the fatigue life of the fatigue crack; the drilling or crack welding can reduce the rate of fatigue crack propagation further on the CFRP reinforcement; However, the application of CFRP without prestressing results in little repair for short cracks.