非对称悬索桥施工过程抗风稳定性研究

Wind stability of a structurally non-symmetric suspension bridge

以目前世界最大跨度的非对称结构型式的悬索桥——西堠门大桥为工程背景,分别模拟主梁从中跨跨中向两侧桥塔、从两侧桥塔向中跨跨中以及从两侧桥塔和中跨跨中同时向中跨四分点处对称拼装的施工顺序,采用三维非线性空气静力和动力稳定性分析方法,分析了主梁拼装过程结构的动力特性、空气静力和动力稳定性的演变规律,并从抗风稳定性角度提出了合理的主梁拼装顺序.结果表明:主梁从中跨跨中向两侧桥塔对称拼装时,结构可以获得较大的自振频率,同时具有较好的空气动力稳定性;主梁从两侧桥塔向中跨跨中对称拼装施工时,结构的静风稳定性最好;从总体抗风稳定性而言,主梁采用从中跨跨中向两侧桥塔对称拼装的施工顺序则比较有利.

Taking the world＇s biggest asymmetric suspension bridge-Xihoumen Bridge-as example, 3D nonlinear aerostatic and aerodynamic analysis were carried out to investigate the evolution of structural dynamic characteristics, the aerostatic and aerodynamic stability during deck erection process. In order to select a favorable deck erection sequence with respect to the wind stability, three different sequences of deck erection were simulated as： （1） from the midpoint of the center span to bilateral pylons （midspan to pylons）; （2） from bilateral pylons to the midpoint of the center span （pylons to midspan）; （3） simultaneously from bilateral pylons and the midpoint of center span to the quarter points of the center span （four working fronts）. The simulation results show that, under the sequence of midspan to pylons, greater structural frequencies and better aerodynamic stability are achieved; whereas, the best aerostatic stability is achieved under the sequence of pylons to midspan. On the whole, the sequence of midspan to pylons seems to be more favorable with respect to the wind stability.