H型桥梁断面颤振后能量图谱  

Post flutter energy map for H-shaped bridge girder

作　　者：赵林[1,3] 胡传新 周志勇[1,3] 葛耀君[1,3] ZHAO Lin;HU ChuanXin;ZHOU ZhiYong;GE YaoJun(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;School of Urban Construction,Wuhan University of Science and Technology,Wuhan 430065,China;Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]武汉科技大学城市建设学院,武汉430065 [3]同济大学桥梁结构抗风技术交通运输行业重点实验室,上海200092

出　　处：《中国科学：技术科学》2021年第5期505-516,共12页Scientia Sinica(Technologica)

基　　金：国家重点研发计划(编号:2018YFC0809600,2018YFC0809604);国家自然科学基金(批准号:51678451)资助项目。

摘　　要：利用同济大学自主研发的三自由度随机强迫振动装置,实现了大扭转振幅下桥梁气动力高精度测量,分析了自激力随折减风速和振幅变化的能量演变效应,描述了可预测颤振分岔的能量图谱,提出了一种基于能量演变的桥梁主梁断面颤振后研究策略.以旧塔科马大桥H型主梁断面为例,分析了颤振后形态及其机理,并反演了旧塔科马大桥风毁失稳路径及其可能发展路径.研究发现,桥梁结构颤振响应取决于结构阻尼比、结构刚度及来流风速之间的竞争关系.推荐研究策略可以精确量化主梁颤振及颤振后响应幅值、来流风速和阻尼比依赖关系,并基于能量视角解释了桥梁颤振分岔失稳路径的发展模式,澄清了气动力非线性和结构扭转阻尼比演变对旧塔科马大桥颤振后极限环振动形态的影响机制.In this study,with the help of the three-degree-of-freedom random forced vibration device developed independently by Tongji University,high-precision measurement of bridge aerodynamic force under large torsional amplitude was realized,and a potential energy spectrum was established in consideration of the energy evolution and amplitude effect that varies with reduced velocity.As a result,a new research strategy for nonlinear flutter of bridge girders is proposed.Taking the Old Tacoma Narrows Bridge as an example,the mechanism of nonlinear vibration phenomena at post-flutter state was analyzed,and the wind-induced instability path of the bridge and its potential development path were deduced.The results show that flutter response can be divided into two components according to the energy spectrum.One component is related to the aerodynamic effect,and the other component is related to the mechanical damping ratio effect,which is helpful for studying the relationships between the mechanical damping ratio and bifurcation phenomena of bridge flutter.At the collapse of the Old Tacoma Narrows Bridge,both the aerodynamic nonlinearity and variations of the mechanical damping ratio with vibration amplitude have important contributions to the post-flutter behavior of the bridge in terms of energy effects.Variations of the mechanical damping ratio in torsion with amplitude greatly improve the flutter performance of the bridge.Thus,the development path of the structural displacement response depends on the competitive relationships among the structural torsional damping ratio,structural rigidity,and oncoming wind velocity.

关 键 词：桥梁断面 颤振后 能量图谱 超限振幅 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]