流线型箱梁断面的自激气动力与振幅非线性相关。为更加准确地预测颤振临界风速，同时探索大振幅振动下的颤振后状态，建立数值风洞模型识别出随折算风速与振幅变化的气动自激力，并计算出相应的非线性颤振导数。在经典的颤振理论基础上，提出更加精细的考虑颤振幅值因素的二自由度复模态特征值求解方法。基于此方法，编制了非线性颤振幅值幅响应搜索程序，并对颤振后幅值特性进行研究。研究表明：单频单自由度振动下，随着幅值增大，桥梁断面气动力非线性成分比重扩大，单频单一扭转运动下尤其明显。所建立的颤振求解方法能准确预测颤振临界风速。流线型箱梁发生颤振后，振幅会出现阶跃性增长，达到某一大幅值后，又基本处于振幅缓增的振动状态。
Abstract
The self-excited aerodynamic force of the streamlined box girder cross section is related to the amplitude nonlinearly.In order to predict the flutter critical wind speed accurately and then explore the post flutter state with the large amplitude vibration, self-excited aerodynamic forces varying with converted wind speeds and amplitudes were identificated based on the established numerical tunnel wind model.Then the corresponding nonlinear flutter derivatives were calculated.On the basis of the classical flutter theory, a finer complex modal eigenvalues solution method of two degrees of freedom, considering the factors of flutter amplitudes, was proposed.Based on this method, a program for searching the nonlinear flutter amplitude response was developed, and the amplitude characteristics after flutter were investigated.The results show that under the single frequency vibration of single degree of freedom, the proportion of aerodynamic nonlinear components increases with the amplitude of bridge section, especially the single twist.The flutter analysis method developed in this paper can accurately predict the flutter critical wind speed.After flutter, vibration amplitude will appear a step growth.When achieving a substantial value, the amplitude will be in the vibration state of increasing slowly.
关键词
流线型箱梁 /
非线性颤振导数 /
颤振求解 /
颤振后状态
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Key words
streamlined box girder /
nonlinear derivatives /
flutter analysis /
post flutter state
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