大跨度非对称悬索桥振动基频的参数敏感性分析

为了研究大跨度非对称悬索桥的动力特性，基于ANSYS软件建立了某大跨度主缆不等高支承悬索桥的三维有限元模型。在计算自振频率时考虑了表征结构非对称的参数，进行了前20阶模态分析，并分析了矢跨比、结构非对称参数、加劲梁抗弯刚度及主塔抗弯刚度等关键结构参数对其振动频率的影响。研究结果表明：不同的参数对非对称悬索桥振动基频的敏感性不同，一阶竖弯和扭转频率随矢跨比的增大减小，相对于正对称的振动频率，反对称的频率对矢跨比参数更敏感；非对称悬索桥的一阶反对称竖弯和扭转基频不受非对称结构参数的影响，而正对称竖弯和扭转基频随非对称结构参数的增大而减小；一阶横弯的自振频率对加劲梁刚度的变化非常敏感，当加劲梁的抗弯刚度增加到原来的3倍时，结构原有的振型次序发生了改变，但主塔抗弯刚度参数的变化对结构各向频率的影响很小，研究结果可为非对称悬索桥的结构设计和动力分析提供参考。

Sensitivity analysis of parameters for vibration frequency of long-span asymmetric suspension bridge

To study the dynamic characteristics of long-span asymmetric suspension bridges，the three-dimensional finite element model of a long-span suspension bridge with unequal height support of main cable is established by ANSYS. The asymmetric parameters of the structure are taken into account when the frequency of the vibration is calculated, and the first 20 modal modal analysis is carried out, and the effects of the key structural parameters, including the ride-span ratio, the asymmetric structural parameter, the stiffness of the main girder, and the stiffness of the main tower, on the vibration frequency are analyzed. The results indicate that the sensitivity of different parameters to the vibration fundamental frequency of asymmetrical suspension bridges is different. The first vertical and torsional vibration frequencies decrease with the increase of the rise-span ratio, and the anti-symmetric frequency is more sensitive to the rise-span ratio than the symmetric vibration frequency. The first anti-symmetric vertical and torsional fundamental frequencies of asymmetric suspension bridges are not affected by asymmetric structural parameters, while symmetrical vertical and torsional fundamental frequencies decrease with the increase of asymmetric structural parameters. The first transverse vibration frequency with the stiffness of main girder is very sensitive. The original mode of structural vibration has changed when the stiffness of main girder is increased to 3 times the original bridge. However, the change of the bending stiffness parameters of the main tower has little effect on the structural frequency. The results can provide reference for the structural design and dynamic analysis of long-span asymmetric suspension bridges.