Abstract: The lateral stability of large span arch bridg is almost absolutely in charge of the safety of construction and a bridge with the increase of the bridge span．X-style arch Bridge Can improves the lateral stability of a bridge．In the paper．according to linear elastic theory and geometrically nonlinear behavior，the lateral stability of CaiYuanBaYangtse Bridge is analyzed and calculated by the finite element of space beams and cables．At the same time．the stability influence ofthe angle of toe-in of the arch rib is explored by the analysis the finite models．It gets the suitable values ofthe angle of toe-in ofthe arch rib that have great influence on the lateral stability and the resoults may be used as a base of design of X-style arc bridge．

Key words: finite element, X-style arch bridge, stability, equivalent load

摘要： 随着拱桥跨度的增加，拱桥的横向稳定问题成为拱桥安全性的重点，而提篮拱与相同跨度直立平行肋拱相比，将大大提高拱桥的稳定性，而得以在大跨径拱桥中使用．本文对菜园坝大桥施工及成桥状态，采用空间杆件(索)单元，研究了线弹性状态及几何非线形的稳定性安全系数，并研究了拱肋内倾角的大小对其稳定性的影响，得到了基于面外稳定性的合理内倾角值，为此类桥梁的设计提供了理论基础．

关键词: 有限元, 提篮拱, 稳定性, 等效荷载