Abstract: Steel cable-stayed bridge with multi-tower, separate twin-decks and asymmetrical cable plane is a typical spatial structure. The number of cable is large, so it’s difficult to determine unstressed length of each cable directly. Taken Jiashao Bridge with six-towers, double decks and four space cable planes as the research subject, firstly based on the principle of equivalent stiffness, the main bridge structure was simplified as a planar structure, to determine its reasonable equivalent cable force; secondly a principle of distribution cable force was put forward, and the flat equivalent cable force was transformed into space cable force; finally unstessed length of each cable was calculated based on catenary equation. The method can quickly and accurately determine unstressed length of each cable.

Key words: bridge engineering, cable stayed bridge with mlti-tower separate, twin-decks and asymmetrical cable plane, unstressed length of cable, cable finished

摘要： 多塔、分幅、内外侧索面不对称钢斜拉桥属典型空间结构，其斜拉索数量较多，直接确定每根斜拉索无应力长度非常困难。以六塔、双幅、空间四索面的嘉绍大桥为研究对象，首先基 于刚度等效原则，将主桥空间结构等效简化为平面结构，确定其等效合理成桥索力；其次提出索力分配原则，将所确定的平面成桥索力转化为空间索力；最后利用悬链线方程求出每根斜拉索 的无应力长度。经实践验证，该方法可快速、准确地确定各斜拉索的无应力长度。

关键词: 桥梁工程, 多塔、分幅、不对称索面斜拉桥, 无应力索长, 成品索长, 等效刚度, 悬链线方程