斜拉桥钢锚拉板区域焊接应力消除试验研究

对重庆江津观音岩大桥索梁锚固区域部分进行了3个足尺比例试件的焊接残余应力测试,并对其焊缝进行了超声波冲击试验,以研究超声波冲击对钢锚拉板区域各焊缝应力的影响情况。测试和试验研究结果表明,钢锚拉板区域各焊缝存在着相当大的焊接残余应力,特别是在平行于焊缝长度方向的应力,不少测点已接近屈服强度。通过采用超声波冲击工艺,大幅度地减小和消除了该区域的焊缝残余拉应力,3个试验试件的各焊缝在平行和垂直于焊缝长度方向的应力平均下降50%以上,最大的下降96.5%,不少测点应力已由拉应力变为了压应力,有效地改善了应力的状态,从而使结构的受力更合理,应力分布趋于均匀。超声波冲击可以作为一种解决斜拉桥桥钢锚拉板区域焊接应力过大问题的有效的方法,对提高接头的疲劳寿命有明显作用。

Experimental Study on Releasing Welding Residual Stress in Steel Tensile Anchor Plate Area of Cable-stayed Bridges

Three full-scale models were made to test the weld residual stress in anchorage areas of Chongqing Jiangjin Guanyinyan Yangtze River Bridge.Furthermore,ultrasound impact was imposed on welds of the models in order to investigate how the welding residual stress in anchorage areas was affected.The results of the test show that(1) there is quite considerable welding residual stress in anchorage areas,especially the stress in the direction parallel to the length of the weld;(2)even many stresses are close to the yield strength.The weld stress was significantly reduced and eliminated by using ultrasound impact technology.The average residual stresses which were parallel and perpendicular to the direction of the weld length fell more than 50 percent in the three test models.The largest one dropped 96.5 percent.Many stresses had changed from tensile stress into compressed stress.This change made the distribution of the weld stress smoother and more reasonable.Thus it effectively improved the state of stress in the structure.Ultrasound impact can be used as a way to solve the problem of welding residual stress in local area of cable-stayed bridge.It will play a significant role in improving the joint fatigue life.