千米级斜拉桥扁平钢箱梁的局部力学行为

Local Mechanical Behavior of Flat Steel Box Girder for Kilometer-Level Cable-Stayed Bridge

以世界最大跨径斜拉桥苏通长江大桥为工程背景,通过静载试验与全桥整体及箱梁局部有限元数值计算研究了千米级斜拉桥扁平钢箱梁各主要板件的力学特性.在此基础上,运用子模型法对考虑焊接构造的箱梁局部焊接细节建立精细有限元模型,分析焊缝周围的应力分布规律,并通过试验加以验证.结果表明,扁平钢箱梁剪力滞效应明显,顶底板纵向应力沿横截面呈不均匀分布,顶板和顶板U肋的焊缝周围存在严重的应力集中,是整个钢箱梁疲劳性能研究的重点部位.

By using static load tests and FEM numerical calculation of the whole bridge and local box girder, Sutong Yangtze River bridge, whose span is the longest among the cable-stayed bridges of the world, was taken as an ex- ample to investigate the mechanical properties of the main parts of the flat steel box girder in kilometer-level cable stayed bridges. On this basis, a fine finite element model of the welded details in the steel box girder including welded conformation was built with submodel technique to analyze the stress distribution along the weld toe, which was verified through test. The research results indicate that the transverse shear lag effect of the steel girder is signifi- cant and the longitudinal stress distributions of the slab and floor beam are non-uniform, with serious stress concen- tration along the weld toe of the slab beam and its rib wall, which is the key part in fatigue performance research of the whole steel box girder.