加劲索对大跨三塔铁路斜拉桥动力特性的影响研究

为研究加劲索布置和刚度对三塔铁路斜拉桥动力特性的影响,以蒙华铁路洞庭湖大桥为工程背景,采用有限元软件ANSYS建立模型,分析设置主塔交叉索,塔、梁加劲索和塔顶水平加劲索对大跨三塔铁路斜拉桥动力特性的影响,并对加劲索不同布置形式下其刚度变化对动力特性的影响进行参数化研究。结果表明:加劲索对侧弯频率几乎没有影响;设置主塔交叉索对扭转频率有一定的提升,而设置塔、梁加劲索和设置塔顶水平加劲索对此几乎没有影响;加劲索能够大幅提高三塔斜拉桥的竖弯频率,且在相同刚度条件下,设置主塔交叉索对三塔斜拉桥竖弯和纵飘频率的提升最大,设置塔顶水平加劲索次之,设置塔、梁加劲索最小。

Study of Influence of Stiffening Cables on Dynamic Property of Long-Span Three-Pylon Cable-Stayed Railway Bridge

To study the influence of layout and rigidity of stiffening cables on the dynamic property of three-pylon cable-stayed bridge,the Dongting Lake Bridge on Mengxi-Central China Railway is cited as the engineering example.The finite element software ANSYS was used to establish the model of the bridge,to analyze the influences of adding crossed cables on pylons,stiffening cables connecting pylons and girder as well as horizontal stiffening cables on tops of the pylons on the dynamic property of the long-span three-pylon cable-stayed railway bridge.And the effect of rigidity variation of stiffening cables when arranged in different ways on the dynamic property was parametrically studied.The results demonstrate that stiffening cables almost have no influence on the lateral bending frequencies.Adding crossed cables on the pylons can certainly improve the torsional frequencies,while the addition of stiffening cables connecting pylons and girder and horizontal stiffening cables on tops of pylons almost have no influence on the torsional frequencies.Stiffening cables can significantly enhance the vertical bending frequencies of three-pylon cable-stayed bridge.When the rigidity is constant,the vertical bending and longitudinal floating frequencies of three-pylon cable-stayed bridge can obtain the maximum enhancement by means of adding crossed cables on pylons,and the effect of horizontal stiffening cables on tops of pylons is moderate,and the effect of stiffening cables connecting pylons and girder is minimal.