Abstract: Magnetic measurement method is a new method of stress measurement，based on the piezomagnetic effect of ferromagnetic materials. Firstly，the principle of magnetic measurement method is introduced. The welding stress after completion of welding and after ultrasonic impact is tested by magnetic measurement method，in the cases of studying 3 full-scale models of Guanyinyan Yangtze River Bridge. The test results show that there is a large welding residual stress in parallel direction and the direction perpendicular to welds，and most of them are close to the yield strength of steel; local structural design is significant for the prevention of welding stress concentration; the ultrasonic impact is showed significant to eliminate welding residual stress. Experimental results show that the magnetic measurement method can effectively test the welding stress of the bridge steel members and that it is a reliable means for people to understand the weld stress distribution of the bridge. The proposed magnetic measurement method has good potential because of its high sensitivity，simple test system and the flexible operation.

Key words: steel bridge, magnetic measurement method, welding residual stress, test, fatigue strength

摘要： 磁测法是基于铁磁材料压磁效应的应力测量的一种新方法，对这种方法的原理进行了介绍，并通过在3个观 音岩长江大桥足尺比例构件试验研究中，对焊接完成后的焊缝应力和超声波冲击后的焊缝应力采用磁测法进行了 测试。测试结果表明，在熔透焊缝中，平行和垂直焊缝方向都存在着相当大的焊接残余应力，很多测点应力已经接 近钢材的屈服强度;局部构造设计对于防止焊接应力集中有着重要的意义;超声波冲击对消除焊缝残余应力效果 明显，磁测法能方便有效地测试出桥梁钢构件的焊接应力，为人们了解桥梁复杂节点的焊缝应力的分布状况，掌握 消除焊缝残余应力工艺处理后的效果情况，提供了切实可行的测试手段，是一种测试灵敏度高、测试系统简单、操 作灵活的很具发展前景的焊缝应力测试方法。

关键词: 钢结构桥梁, 磁测法, 焊接应力, 测试, 疲劳强度