为了解决桥梁钢箱梁U肋角焊缝中疲劳裂纹的检测问题，针对U肋角焊缝疲劳裂纹特点进行了研究。通过分析疲劳裂纹成因及各类无损检测方法的特点，可知采用超声相控阵检测U肋角焊缝较为合适。为了验证超声相控阵检测U肋角焊缝疲劳裂纹的可行性，先通过仿真软件建立U肋角焊缝截面模型并模拟声束覆盖，在此基础上制作一套带有人工缺陷的U肋角焊缝试块进行室内验证，最后应用于某桥梁的现场检测实践上。结果表明：超声相控阵在U肋角焊缝疲劳裂纹的检测上十分有效，能有效减小U肋角焊缝疲劳裂纹的检测盲区，降低疲劳裂纹的漏检率。

In order to solve the problem of fatigue crack detection in U rib fillet weld of steel box girder of bridge, the fatigue crack characteristics of U rib fillet weld were studied. By analyzing the causes of fatigue cracks and the characteristics of various non-destructive testing methods, it is found that the ultrasonic phased array testing is the most suitable one. In order to verify the practicability of ultrasonic phased array in detecting fatigue cracks of U-rib fillet weld, the section model of U-rib fillet weld was established through simulation software and the acoustic beam coverage was also simulated. On this basis, a set of U-rib fillet weld test blocks with artificial defects were made for indoor verification, and finally applied to the field practice of a bridge.