锚拉板式索梁锚固结构焊缝抗疲劳性能研究

以组合斜拉桥锚拉板式索梁锚固结构为对象,进行1∶2.5的锚拉板式索梁锚固结构缩尺模型疲劳试验,并采用MSC Marc有限元软件建立有限元模型进行数值模拟,研究了锚拉板式索梁锚固结构中锚拉板的应力分布规律及疲劳性能.结果表明,锚拉板式索梁锚固结构关键部位为锚拉板与加劲肋、主梁顶板间连接焊缝处,以及锚拉板中部开口附近部位;循环加载过程中的动应变时程曲线和静载时测点应力-荷载曲线均基本呈线性关系,静载时测点的Von Mises应力、测点应力-荷载曲线均不随荷载循环次数发生变化,锚拉板试验模型处于弹性工作状态;200万次疲劳试验后,整个试验模未出现裂纹和异常现象;该锚拉板式索梁锚固结构所有焊缝的应力幅小于BS5400规定的容许疲劳应力.

Study on the weld's anti-fatigue performance of cable-to-girder anchorage with tensile anchor plate

Based on the cable-to-girder anchorage with tensile anchor plate of a composite cable-stayed bridge, an experiment on a 1:2.5 scale-model was conducted, and finite element (FE) analysis is carried out by software of MSC. Marc to reveal the regularity of stress distribution and fatigue performance of the tensile anchor plate for cable-stayed bridge. It is found that the critical locations of the cable-to-girder anchorage with tensile anchor plate include the welding seam where tensile anchor plate associates with stiffeners and the beam, besides the anchor tensile plate openings near the central part. Both time-history curves of the dynamic strain and the stress-static load curve show linear relationships in loading process, and cycle-index had little influence on Von. Mises stress and stress-static load curve of test points, which presents that the test model remains elastic. No fatigue cracks and abnormal phenomena were found in the whole of the tensile anchor plate after the 2-million cycles of fatigue loading test. The stress that stems from the welding seam of the cable-to-girder anchorage with tensile anchor plate is all less than the allowable fatigue stress provided in standard of BS5400.