基于ANSYS的桥梁全模态颤振频域分析方法

Full-mode Flutter Frequency Domain Analysis Method of Bridge Based on ANSYS

提出了一种在ANSYS中直接分析大跨桥梁三维全模态颤振的有限元模型和频域方法。该有限元模型采用ANSYS的自定义单元Matrix27来模拟桥面受到的自激气动力,而将单元Ma-trix27的刚度或阻尼矩阵描述成风速和振动频率的函数。通过阻尼特征值分析,确定风-桥耦合系统的各复特征值,其中复特征值的实部为阻尼而其虚部则为振动频率;并给出了求解系统各阶复模态特性随风速变化的迭代算法。最后以一简支梁桥和一悬索桥算例验证了颤振分析模型和方法的正确性和可靠性。该方法能使桥梁设计人员和研究人员可以直接利用ANSYS来分析大跨桥梁的耦合颤振。

Authors presented a finite element （FE） model and frequency analysis method for analyzing 3-D full-mode flutter of long-span bridges using ANSYS software. This model utilized a special kind of element Matrix27 in ANSYS to simulate the aeroelastic forces acting on bridges, wherein the stiffness or damping matrixes of Matrix27 elements were described as function of wind velocity and flutter derivatives. Using this FE model, damped complex eigenvalue analysis was then carried out to determine the complex eigenvalues of wind-bridge coupled system; the real part of complex eigenvalues was damp while the imaginary part was vibration frequency. The iteration algorithm for solving variation of system order was put forward. Validity of the method was verified and a suspension bridge. The proposed method enabl practitioners to analyze flutter instability by using ANS complex mode property vs wind velocity by example of a simple-supported bridge es the bridge designers and engineering YS.