In-plane free vibrations of shallow cables with cross-ties
In-plane free vibrations of shallow cables with cross-ties
复制标题
带拉杆的浅电缆的面内自由振动
DOI：
10.1002/stc.2421
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发表时间：
2019
影响因子：
5.4
通讯作者：
Chen Lin
中科院分区：
文献类型：
--
作者：
Sun Limin;Hong Dongxiao;Chen Lin
斜拉桥中长拉索的振动控制最有前途的解决方案是采用交叉系杆连接斜拉索。现有的研究主要集中在系杆的结构形式和性质对成网索动力特性的影响上，主要基于索的张弦模型。然而，交叉拉杆特别适用于面内振动会受到垂度效应显著影响的长缆索。因此，本文提出了一种分析方法来研究平面内自由振动的浅索网络的交叉联系，使用浅索的线性理论。详细研究了具有一个粘弹性交叉拉杆的两浅索网络，以了解垂度对索网络动力学的影响。结果表明，垂度效应耦合了由交叉系杆划分的索段的振动，并显著改变了模态相互作用。当枕木是刚性的时，曲线转向发生在系统频率曲线之间，与没有垂度效应时的曲线相交相比，曲线转向发生在枕木位置变化时。当系杆是柔性的时，一般来说，索段和整个索的振型既不是反对称的，也不是对称的，垂度会影响几乎所有的振动模态。此外，考虑枕木的阻尼效应后，复平面内关于枕木阻尼系数增量的频率轨迹仍然可以通过相应的无阻尼和固支频率进行分类，而模态相互作用变得更加复杂。从定量上讲，当垂度参数在既有斜拉桥的实用范围内时，对索网的第一、二阶振型影响较大，需要在实践中加以考虑。
Connecting stay cables with cross‐ties is the most promising solution for vibration control of long cables in cable‐stayed bridges. Existing studies have been focusing on the influences of the cross‐tie configurations and properties on the dynamics of the formed cable networks, mostly based on the taut‐string model of cables. However, the cross‐ties are particularly aimed at long cables whose in‐plane vibrations can be significantly affected by the sag effect. This paper therefore presents an analytical method to investigate free in‐plane vibrations of shallow cable networks with cross‐ties, using the linear theory of shallow cables. A two‐shallow‐cable network with one viscoelastic cross‐tie is studied in detail to appreciate the sag effect on the dynamics of the cable network. It is shown that the sag effect couples vibrations of the cable segments divided by the cross‐ties and changes the modal interactions substantially. When the cross‐tie is rigid, curve veering occurs between frequency curves of the system with respect to varying cross‐tie location, as compared with curve intersection in the absence of the sag effect. When the cross‐tie is flexible, generally, mode shapes of the cable segments and the whole cable are not antisymmetric nor symmetric, and the sag then affects nearly all the vibration modes. Furthermore, taking into account the damping effect of the cross‐tie, the frequency loci in the complex plane regarding the increment of cross‐tie damping coefficient can still be categorized by the corresponding undamped and clamped frequencies while the modal interaction becomes more complicated. Quantitatively speaking, when the sag parameter is in the practical range of existing cable‐stayed bridges, the first and second vibration modes of the cable networks are considerably affected and need to be considered for practice.