为了深入研究大跨度多塔悬索桥的动力特性，基于 ANSYS 软件建立了某大跨度四塔悬索桥的三维有限元模型，采用 Block Lanczos 法进行模态分析，以获得该桥的自振频率和振型，并分析了主缆矢跨比、恒载集度、主梁刚度以及中塔刚度等结构关键参数对其动力特性的影响．结果表明：该桥基频为0．07171 Hz，对应振型为主梁一阶正对称侧弯；增大矢跨比有利于提高大桥颤振性能；随着恒载集度的增加，结构各阶自振频率均有不同程度的下降；增大主梁横向和扭转刚度可分别提高主梁侧弯和扭转频率，而增大主梁竖弯刚度对主梁竖弯频率影响较小；主梁一阶竖弯频率随着中塔纵向刚度的增大而显著提高．研究结果可为大跨度多塔悬索桥的结构设计与动力分析提供参考．%To investigate the dynamic characteristics of long-span multi-tower suspension bridges, the three-dimensional finite element model for a long-span quadruple-tower suspension bridge is es-tablished by ANSYS.Modal analysis is carried out by using the Block Lanczos method to obtain the natural frequencies and the mode shapes of the bridge.And the effects of the key structural parame-ters,including the sag-to-span ratio,the dead load,the stiffness of the main girder,and the rigidity of the mid-pylon,on the dynamic characteristics are analyzed.The results indicate that the funda-mental frequency of the bridge is 0.071 71 Hz and the corresponding vibration mode is the first sym-metric lateral bending mode of the main girder.The increase of the sag-to-span ratio can improve the flutter performance.With the increase of the dead load,the natural frequencies decrease with differ-ent degrees.When the lateral stiffness and the torsional stiffness of the main girder increase,the lat-eral vibration frequencies and the torsional vibration frequencies increase,respectively.However, the vertical stiffness of the main girder has little influence on the vertical vibration frequencies.The first vertical vibration frequency increases significantly with the increase of the longitudinal rigidity of the mid-pylon.The research results can provide reference for the structural design and dynamic anal-ysis of long-span multi-pylon suspension bridges.
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