桥面激励下的斜拉索减振设计研究

Study on the stay cable mitigation under the bridge deck excitation

针对已有的斜拉索减振模型不能合理分析桥面运动对斜拉索减振效果影响的现状,基于几何位移关系推导出适用于桥面运动的计及阻尼器耦合振动的斜拉索减振分析平衡方程,建立了合理的阻尼器参数设计理论模型,采用数值迭代算法对拉索—阻尼器系统的模态阻尼特性进行了数值分析。结果表明,由于桥面耦合作用的影响,阻尼器安装位置对系统模态阻尼的影响不再具有对称性,桥面运动条件下,拉索—阻尼器系统的模态阻尼比与拉索的倾角有关,系统的模态阻尼相同时,斜拉索的倾角越小,外部阻尼器参数越大。

In order to overcome the shortcomings in reasonably considering the impact of bridge deck movement on the effect of control system for stay cable. A new equation of motion based on the relationship of the geometric displacement is developed in order to analysis the coupling effects among deck-cable-damper. The mode damping properties of the cable-damper system were extracted by numerical iteration analysis technique. To investigate the affects of modal damping of the cable-damper system subjected to the coupling motion with the deck, the normalized damping ratio is calculated by a numerical process of the normalized damper coefficient for different support conditions. The result shows that the symmetry of damper mounting position versus the mode damping ratio of the system could not hold since the coupling effects of bridge deck movement, the external damping should be greatly increased to provide the same non- dimensional modal damping with the decrease of the stay angle, and that existing models overestimated the value of the non-dimensional modal damping. New model matches well with the actual occurrence in bridge engineering.