双肢人字形独塔斜拉桥整体温度效应影响研究

Influence Study of Gross Temperature Effect on Coupled-component Cable-stayed Bridge with Herringbone Shape Pylon

为了造型新颖美观,一些市政桥梁设计采用了异形独塔斜拉桥设计,索塔形状设计上也别出心裁,如出现了桥塔纵向布置为"人字形"的异形独塔斜拉桥。为考察此类结构的受力特性,以某双肢人字形独塔斜拉桥为例,采用Midas有限元程序计算分析了在整体温度效应作用下,通过改变桥梁连接方式,对比分析了主梁、主塔与副塔结构的应力分布情况。分析结果表明:主塔、副塔固结或者竖向支撑主梁,结构整体温度效应产生的桥塔最大拉应力发生在在副塔塔底处,且均超过4 MPa;主塔固结,副塔与主梁分离的情况下,整体温度效应产生的应力较小,最大拉应力小于1MPa。即随着副塔塔梁处刚性连接的释放,主塔及主梁的整体温度应力也随之减少。因此,采用主塔与主梁固结,副塔与主梁完全分离的边界形式能有效地减小整体升温作用下桥塔的应力,是较为适宜的桥塔边界形式。

Aiming at a better aesthetic appearance, different types of unique single-pylon cable-stayed bridge including herringbone shape pylon cable-stayed structure are designed in some municipal bridges. In order to analyze mechanics performances of herringbone shape pylon, FEM is established by Midas/Civil software based on a coupled-component cable-stayed bridge. Furthermore, comparative analysis on girder, major tower and subordinate tower under various boundary conditions are conducted. The research results show that the maximum tensile stress, which occurs in the bottom of subordinate pylon, is up to 4MPa under condition 1 and condition 2. And the secondary maximum tensile stress both occur in the joint of pylons and girder. In the case of condition 3, both of the stresses of pylons and girder are small under gross increasing temperature effect, in which the maximum value is less than 1MPa. Finally, as the articulation of subordinate pylon and girder decreasing, the pylons and girder stresses of the bridge reduce under gross increasing temperature effect. It is strongly recommended that the subordinate pylon should not be rigid with the girder for herringbone shape pylon in longitudinal direction.