加劲梁形式及支承体系对三塔悬索桥整体刚度影响研究

Influences of Forms and Supporting System of Stiffening Girder on Global Stiffness of Three-Tower Suspension Bridge

为探讨加劲梁形式及支承体系对三塔悬索桥整体刚度及中主鞍座槽内主缆抗滑移稳定性的影响,以(225+850+850+225)m的鹦鹉洲长江大桥为背景,选取不同加劲梁形式及支承体系,拟定6种组合工况,通过桥梁结构非线性分析系统BNLAS对不同组合下结构竖向、横向刚度及主缆抗滑移稳定性进行计算分析。结果表明:加劲梁采用钢-混组合梁形式,结构竖向和横向刚度较采用钢箱梁时大;加劲梁支承体系对结构整体竖向刚度影响不大,但对加劲梁局部竖向转角影响明显,简支支承体系梁端转角较大;加劲梁支承体系对结构整体横向刚度影响明显,表现为简支体系横向刚度较小,飘浮和半飘浮体系横向刚度较大;加劲梁采用自重较大的钢-混组合梁形式以及设置纵向固定支座,对主缆抗滑移稳定有利,此外考虑荷载偏心计算主缆抗滑移稳定性更偏于安全。

To examine the influences of the forms and supporting system of stiffening girder on the global stiffness of the three-tower suspension bridge and the anti-slipping stability of the main cable inside the grooves of the central tower saddle,the Yingwuzhou Changjiang River Bridge with span arrangement of（225＋850＋850＋225）m was cited as an example.Six combined loading conditions were figured out responding to different stiffening girder forms and supporting systems,the BNLAS,a kind of non-linear analytical system for bridge structures,was used to calculate and analyze the vertical and transverse stiffness as well as the anti-slipping stability of the main cable under different loading conditions.The results demonstrate that the steel-concrete composite girder results in greater vertical and transverse stiffness,compared to the steel box girder.The supporting system of the stiffening girder has minimal influence on the global vertical stiffness of the structure,but obvious influence on the local vertical rotation angle of the stiffening girder,and the simply-supported system has greater beam-end rotation angle.The supporting system of the stiffening girder exerts notable influence on the global transverse stiffness of the structure,specifically,the transverse stiffness of the simply-supported system is small,but the transverse stiffness of the floating and half-floating systems is big.Using the steel-concrete composite girder with heavy weight and installing longitudinal fixing bearings are favorable to the anti-slipping stability of the main cable.Moreover,it is safer to calculate the anti-slipping stability of the main cable with the consideration of the load eccentricity.