悬索桥颤振的多模态耦合及机理研究
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摘要
将桥梁结构与气流作为一个系统 ,从能量平衡的角度研究系统的颤振稳定性。首先建立了系统能量变化率与系统等效阻尼比之间的关系 ,由不同风速下系统的等效阻尼比判断系统的颤振稳定性 ,推演了系统及各阶模态等效阻尼比的计算方法。以英国塞文桥为算例 ,验证了本方法的可靠性 ,并用于对系统发生颤振时多模态间的耦合机理进行研究。为了进一步探明多模态耦合对不同体系悬索桥颤振稳定性的影响 ,以我国虎门悬索桥和一座跨海桥设计方案为工程背景 ,证实了由扁平钢箱梁作为主梁的悬索桥 ,若结构对称其颤振形态将为对称模式 ,且系统颤振主要受第一阶对称扭转模态及低阶对称竖弯模态控制 ,高阶模态的影响很小 ;并发现了一个新的现象 :对于单跨悬索桥 ,多模态分析所得临界风速一般低于二模态分析结果 ,而对于三跨悬索桥(包括三跨两铰和三跨连续 )趋势正好相反 ,这一发现对于工程实践将具有重要意义。
A flutter stability of the suspension bridge is studied from the standpoint of energy balance. The relation between the change ratio of a system energy and the equivalent damping ratio of the system is built. A method to calculating the equivalent damping ratio of each mode and system is proposed in the paper. The flutter stability of a system is depended on the equivalent damping ratio of different wind speed. The reliability of the method is illustrated by the British Severn bridge. The mechanism of multi?mode coupling when a system induced flutter is also examined in the paper. To illustrate the influence of multi?mode coupling on different structural systems of suspension bridges, the Humen bridge and the designed project of a sea?crossing bridge are taken as an example. Some useful conclusion is obtained through the study.
A flutter stability of the suspension bridge is studied from the standpoint of energy balance. The relation between the change ratio of a system energy and the equivalent damping ratio of the system is built. A method to calculating the equivalent damping ratio of each mode and system is proposed in the paper. The flutter stability of a system is depended on the equivalent damping ratio of different wind speed. The reliability of the method is illustrated by the British Severn bridge. The mechanism of multi?mode coupling when a system induced flutter is also examined in the paper. To illustrate the influence of multi?mode coupling on different structural systems of suspension bridges, the Humen bridge and the designed project of a sea?crossing bridge are taken as an example. Some useful conclusion is obtained through the study.
引文
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8 廖海黎 大跨悬索桥风致振动研究 :[博士论文 ] 成都 :西南交通大学 ,1996
9 钟万勰 暂态历程的精细计算方法 计算结构力学及其应用 ,1995 ,12 (1)
10 胡聿贤 地震工程学 北京 :地震出版社 ,1988
11 牛和恩主编 虎门大桥工程 (第二册 )悬索桥 北京 :人民交通出版社 ,1998
2 TanakaH ,YamamuraN ,ShiraishiN .Multi modeflutteranalysisandtwo&threedimensionalmodeltestsonbridgeswithnon analo gousmodalshapes .Proc .JSCE ,1993 ,No .471 I 2 4
3 埃米尔·希缪 ,罗伯特·H·斯坎伦著 风对结构的作用 风工程导论 刘尚培 ,项海帆 ,谢霁明译 上海 :同济大学出版社 ,1992
4 《公路桥梁抗风设计指南》编写组 公路桥梁抗风设计指南 北京 :人民交通出版社 ,1996
5 谢霁明 ,项海帆 桥梁抗风设计的新概念 多振型耦合颤振 土木工程学报 ,1987,2 0 (2 )
6 AgarTJA .AerodynamicFlutterAnalysisofSuspensionBridgesbyaModalTechnique .EngStruct 1989,11(2 )
7 陈政清 桥梁颤振临界风速值上下限预测与多模态参与效应 结构风工程研究的新进展及应用 (张相庭主编 ) 上海 :同济大学出版社 ,1993
8 廖海黎 大跨悬索桥风致振动研究 :[博士论文 ] 成都 :西南交通大学 ,1996
9 钟万勰 暂态历程的精细计算方法 计算结构力学及其应用 ,1995 ,12 (1)
10 胡聿贤 地震工程学 北京 :地震出版社 ,1988
11 牛和恩主编 虎门大桥工程 (第二册 )悬索桥 北京 :人民交通出版社 ,1998
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