悬索桥施工期大尺寸主缆驰振分析方法研究

摘要

针对传统单自由度驰振模型在进行悬索桥大尺寸主缆施工期驰振分析时可能产生误判的问题,建立了一个同时考虑主缆横风向及顺风向运动的二自由度驰振模型.以东海某大跨径悬索桥为例,利用Fluent数值模拟的方法,计算得到该桥主缆施工期几个典型工况不同风攻角下的气动力系数;采用ANSYS建立该桥主塔、主缆及猫道的有限元模型,通过模态分析得到对应工况下主缆的动力特性;选取可能发生驰振失稳的工况,分别利用传统单自由度模型及提出的二自由度模型计算其驰振临界风速并进行对比分析.结果表明,分别利用两种模型所计算的驰振临界风速差别较大,传统单自由度方法对是否发生驰振可能产生误判,从而可为悬索桥大尺寸主缆施工期的驰振分析提供理论参考.%Aiming at the problem that a traditional single-DOF galloping model may cause mis-judging when analyzing galloping of large scale spire type main cable of a suspension bridge during construction,a new 2-DOF galloping model considering the main cable motion along transverse wind direction and down wind direction was established.Firstly,a long-span suspension bridge in the East China Sea was taken as a study object,aerodynamic coefficients of the main cable in its several typical working cases during construction were calculated using the numerical simulation method based on the software Fluent.Secondly,the finite element model of the bridge including main tower,main cable and catwalk was established,and the dynamic characteristics of the main cable were obtained with the modal analysis.Finally,the working cases of the main cable that may have galloping were selected,and galloping critical wind speeds were calculated based on the single-DOF model and the 2-DOf model,respectively and the results were analyzed contrastively.It was indicated that the galloping critical wind speeds based on the two models are quite different,the traditional single-DOF model may lead to a mis-judging if there is a galloping;the results provide a theoretical reference for analyzing galloping of large scale spire type main cable of a suspension bridge during construction.