Abstract: Through the application of the calculation method of the conventional two towers cable-stayed bridge，the simplified static calculation formula of a structural system of multi-tower cable-stayed bridge with tie-down cables is got. Furthermore， a finite element analysis model is established. Taking different set locations of the tie-down cable as parameters，the impact of the tie-down cable layout on the force of main girder is analyzed. The results show that: setting up the tie-down cable can locally increase the axial force on the main girder，but reduce the moment correspondingly; and the bearing on the main beam is less affected by setting up the tie-down cable.

Key words: multi-tower cable-stayed bridge, tie-down cable, main girders, finite element analysis

摘要： 应用常规两塔斜拉桥的计算方法，得出了下拉索体系多塔斜拉桥的简化静力计算公式; 建立了有限元分析模 型，以下拉索的位置设置为参数，分析了下拉索布置对主梁受力的影响。结果表明: 设置下拉索局部地增加了主梁 轴力，但弯矩却相应地减小，对主梁的承载影响较小。

关键词: 多塔斜拉桥, 下拉索, 主梁, 有限元分析