三塔悬索桥中塔结构选型分析

三塔悬索桥作为一种新型的桥梁体系,结构受力特征与两塔悬索桥显然不同.三塔悬索桥整体刚度低、主梁挠跨比大,中塔选择对整个结构的受力有非常显著的影响.本文以泰州桥的三塔双主跨悬索桥为研究背景,分析讨论了三塔悬索桥主梁挠跨比、主缆抗滑移安全系数、主塔截面内力等设计限制下的中主塔刚度的恰当取值,采用有限元方法对中塔纵向采用A型钢塔、A型混凝土塔、I型混凝土塔等不同的结构型式进行了分析.研究发现,中塔纵向刚度是中塔结构选型的关键,在一定的结构体系下,三塔悬索桥中塔的纵向刚度应当在一定范围之内才能满足各种设计条件.分析结果表明,泰州大桥中塔结构的纵向刚度宜在23～28MN／m之间,采用人字形钢中主塔是适宜的.

Structure style selection of the mid-tower of a three-tower suspension bridge

Compared with common two tower suspension bridges, the total stiffness of a three-tower suspension bridge is relatively small, and the ratios of the deflection to span of the bridge are larger. The mid tower structure of a three tower suspension bridge has great influence on the mechanical behavior of the whole bridge. Based on the analysis of the Taizhou Bridge, a three-tower suspension bridge, the design restrictions of a three-tower suspension bridge were analyzed, such as the deflection of the main span and the anti-slipping safety factor between the main cable and saddle of the mid tower. The analysis based on the finite element method shows that the stiffness of the mid tower is the key factor of the mid-tower structure selection, the appropriate stiffness of the mid-tower is between 23～28MN／m for the Taizhou Bridge, and the appropriate structure is a herringbone structure.