Using a spatial composite finite element method, combining three-dimensional solid element and bar element, the mechanical analysis of a two-span curved PC continuous box girder bridge is conducted.

Stiffness matrix and equivalent nodal force formula, which take into account of the influence of shear lag, are derived subsequently on the basis of the definition of stiffness coefficient.

In this paper, a new type of super_element based on the thin_walled bars theory is presented for the lateral stability analysis of the reinforced concrete truss_beam bridge with a box_section.