The results show that the frame system of the spatial string structure contributes to the linear stiffness,and stressing of the cables increases the geometric stiffness.

Four fundamental methods for analysis of P-Δ effect and their characteristics were summarized in this paper,such as the finite element method based on geometric stiffness,the finite element iteration method based on equivalent horizontal forces,the finite element method based on reduction elastic flexural stiffness,and the structural displacement and internal forces enhancement coefficient method.

Reckoning in the geometric stiffness of the rope,the spatial lateral stability of the bridge was analyzed and diverse measures were put forward to improve its lateral stability.

This paper inferred the geometry firm degree formation which influence clasticity con-struction,in depth alternately each other,transport load acting.

Then based on linearity and nonlinearity theory, the live load influence is analyzed for a bridge, which includes the comparison of the influence between initial geometric stiffness, cable sag and large displacement.

In this paper, a improved geometric stiffness matrix of a column element considering axial force-lateral displacement effects is derived.