特大跨悬索桥的缆索体系优化

Optimization of Cable System in Extra Long-Span Suspension Bridge

以提高特大跨悬索桥的动力稳定性为目的,基于优化缆索体系的思路,对三种优化方案进行比较.综合考虑抗风性能、施工、经济等因素,通过力学分析,指出一种行之有效的空间索形体系.以某座主跨1 090 m的跨海悬索桥为算例,就实桥使用的平面索形与本文推荐的空间索形,利用自行编制的程序ECFS,分别计算出初始平衡状态下主缆与吊杆的无应力长度、坐标和张力.利用这些力学、几何参数在ANSYS中分别建立平面、空间索形模型,进行动力分析.经过对两种索形自振特性的对比,分析其振动性能的差异与原因,证实了该空间索形可以有效提高悬索桥的横向刚度、抗扭刚度,从而提升结构的动力稳定性.有可能成为大跨悬索桥的发展方向.

The effort is made in this paper to improve dynamic stability of extra long - span suspension bridge. Aiming at optimizing cable system, three optimization schemes are proposed and compared. One spatial cable system is put forward through mechanical analysis combined with a comprehensive analysis of their wind resistance performance, construction and economy. A sea -crossing bridge with an 1 090 m main span is taken as an example. The program ECFS is written to calculate non - stress length, coordinates and tension of main cables as well as hangers in the initial equilibrium state of spatial cable or plane cable suspension bridge. Using these mechanical and geometrical parameters, both plane cable model and spatial cable model are established to analyze self-vibration characteristics by ANSYS program. The comparision of dynamic characteristics is employed to analyze the difference between the vibration performance of the two kinds of cable systems and its corresponding causes. The results verify that the spatial cable system can effectively enhance bridge transverse stiffness and torsional stiffness, and further increase structural dynamic characteristics. It may become a developing direction of long - span suspension bridge.