超大跨径部分地锚交叉索斜拉桥的索-梁锚固技术

Cable-girder Anchorage Technology of Super-span Cable-stayed Bridge with Partial Ground-anchorage and Cross Stays

针对超大跨径斜拉桥主梁轴压力过大的问题,提出了部分地锚交叉索斜拉桥方案。特殊的结构体系使得交叉索段主梁的整体受力、索-梁锚固构造、局部应力分布与常规斜拉桥不同,有必要对其进行全面的分析。以1 408 m部分地锚交叉索斜拉桥方案与1 408 m常规体系斜拉桥方案为基础,分别建立了整体梁单元模型以及主梁局部模型,在整体受力分析的基础上,进一步分析了扁平钢箱梁在拉索交叉锚固作用下的应力分布。结果表明,新体系斜拉桥相较常规体系斜拉桥主梁最大轴力削减了28.7%;交叉索段主梁锚固区最大Mises应力为108 MPa;拉索水平分力不再累积使得交叉索段主梁整体处于很低的应力水平。证明了新体系斜拉桥主梁受力的优越性以及新型交叉拉索索-梁锚固结构的合理性。

In order to solve the problem of the excessive axial force in main girder of super-span cable-stayed bridge, a type of cable-stayed bridge with partial ground-anchorage and cross stays is proposed. The specific structural system makes differences between this novel cable-stayed bridge system and conventional cable- stayed bridge system on internal force distribution, cable-girder anchorage structure and local stress distribution of main girder. Therefore, it is necessary to conduct a comprehensive analysis of main girder of this new cable-stayed bridge system. In order to analyze the stress distribution of flat steel box girder under the anchor effect on the basis of the results of the global analysis, the single-girder element model and the local accurate model are built up in accordance with an 1 408 m cable-stayed bridge project with partial ground-anchorage and cross stays and an 1 408 m conventional cable-stayed bridge project. The results show that （ 1 ） comparing to the conventional system, the maximum axial force of the main girder of this new system is greatly reduced by 28.7% ; （2） the maximum Mises stress of the main girder anchorage zone in the cross stays segment is 108 MPa; （3） without the accumulation of the horizontal component force of cross stays, the stress of the main girder is in a low level. It shows the excellent mechanical performance of the main girder and the rationality of the new cable-girder anchor in cross stays segment.