The two methods, the linear and nonlinear bucking analyses, to determine the critical
load of a long-span arch bridge of concrete-filled steel tubes were presented. A 3D FE model of
Maocaojie arch bridge in Hunan, as an example, was set up, and its stability was analyzed using
finite element program ANSYS. The effects of geometry nonlinearity, material nonlinearity and
initial defects of the structure on the stability of this arch bridge were investigated. The results show
that large displacement occurs at arch top when loading reaches to the load of stability loss, so the
effect of large displacement should be considered in the analysis of stability; and the material
nonlinearity and initial defects of the structure make its stability decrease.