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通过减小主跨为1 708m悬索桥的主缆间距,分析了内倾式双主缆体系的动力特性和颤振性能.动力特性计算发现:减小主缆间距,能在维持竖弯基频的基础上有效提高扭转基频;附加的侧弯-扭转耦合振型在两个自由度上的等效质量均较小,且频率介于竖弯、扭转基频之间.为说明该振型的侧弯-扭转强耦合效应对颤振稳定性的影响,分别基于二维两自由度和三维全自由度状态空间方法对比分析了颤振性能.二维结果显示,小主缆间距时侧弯-扭转耦合振型较常规纯扭振型对颤振更不利;三维分析显示,主缆间距较小时,上述耦合振型参与程度较高,反之,纯扭振型参与较多,同时第二阶竖弯振型作用明显.结果表明:内倾式双主缆体系悬索桥的颤振稳定性受多振型影响,传统二维两自由度分析结果可能不安全,有必要进行三维全自由度颤振分析.
By reducing the main cable spacing of the main span of 1 708m suspension bridge, the dynamic characteristics and the flutter performance of the double-cable system with inboard tilt are analyzed. The dynamic characteristics calculation shows that reducing the distance between the main cables and maintaining the fundamental frequency of vertical bending The equivalent fundamental mass of the additional side-torsional coupled modes is small in both degrees of freedom, and the frequency is between vertical bend and torsional fundamental frequency. To illustrate the side of this mode Bending-torsional strong coupling effect on the flutter stability, the flutter performance is analyzed based on two-dimensional two-degree-of-freedom and three-dimensional full-degree-of-freedom state space method respectively.The two-dimensional results show that the small- Coupling vibration modes are more detrimental to flutter than conventional pure torsional vibration modes. Three-dimensional analysis shows that the coupling modes are more involved when the main cable spacing is smaller, whereas pure torsional vibration modes are more involved, while the second-order vertical bending The results show that the flutter stability of a suspension bridge with a double main cableway system is affected by the multi-modes, and the traditional two-dimensional two-degree-of-freedom analysis may be unsafe, so it is necessary to analyze the flutter in three-dimensional full degrees of freedom.