Flutter analysis of long-span bridges using ANSYS
Flutter analysis of long-span bridges using ANSYS
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DOI：
10.12989/was.2007.10.1.061
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发表时间：
2007
影响因子：
1.6
通讯作者：
X. Hua;Z. Q. Chen;Y. Ni;J. Ko
中科院分区：
文献类型：
--
作者：
X. Hua;Z. Q. Chen;Y. Ni;J. Ko
本文提出了一种新的有限元（FE）模型，用于分析大跨度桥梁耦合颤振商业有限元软件ANSYS。该模型利用ANSYS中的特定用户定义单元Matrix27来模拟作用在桥梁上的气动弹性力，其中刚度和阻尼矩阵以约化风速和颤振导数表示。利用该有限元模型进行了阻尼复特征值分析，确定了复特征值的真实的部分为对数衰减率，虚部为阻尼振动频率。颤振不稳定性发生的条件是，在某一风速下，包含虚拟Matrix27单元的结构系统具有一个真实的部分为零或接近零的复特征值，该特征值的虚部为颤振频率。通过算例分析验证了所开发的程序的有效性，并验证了ANSYS在悬索桥颤振分析中的应用。所提出的方法使桥梁设计者和工程从业人员能够使用商业有限元软件ANSYS分析颤振不稳定性。
This paper presents a novel finite element (FE) model for analyzing coupled flutter of long-span bridges using the commercial FE package ANSYS. This model utilizes a specific user-defined element Matrix27 in ANSYS to model the aeroelastic forces acting on the bridge, wherein the stiffness and damping matrices are expressed in terms of the reduced wind velocity and flutter derivatives. Making use of this FE model, damped complex eigenvalue analysis is carried out to determine the complex eigenvalues, of which the real part is the logarithm decay rate and the imaginary part is the damped vibration frequency. The condition for onset of flutter instability becomes that, at a certain wind velocity, the structural system incorporating fictitious Matrix27 elements has a complex eigenvalue with zero or near-zero real part, with the imaginary part of this eigenvalue being the flutter frequency. Case studies are provided to validate the developed procedure as well as to demonstrate the flutter analysis of cable-supported bridges using ANSYS. The proposed method enables the bridge designers and engineering practitioners to analyze flutter instability by using the commercial FE package ANSYS.