Spacial Stability Analysis And Program Design For The Large-Span Continuous Rigid Frame Bridge

With the accelerated development of public transportation, large-span continuous frame bridge is highly favored among the bridge engineers by virtue of its unique advantages such as large-span capacity, good co-working performance, reasonable force-bearing mechanism, convenient construction, etc. facing this development trend of large span and high pier, the stability analysis of bridge structures is a key factor to determine whether the design is reasonable. In this paper, we have systematically studied the theories of stability concerning this type of bridge.We have deduced a geometrical stiffness matrix, considering interacting influence of axial force, bending moment and P-Δeffect, based on the principle of stationary potential energy, so a new tangential stiffness matrix is developed and we have compiled a set of corresponding nonlinear programs.In this paper, we have discussed the Eigen value analysis and geometrical nonlinear stability analysis considering shear lag effect. Such analysises are based on the stability theory of spatial three-dimensional bar system FEM, we adopted techniques of mixed-language programming using VB and FORTRAN to compile the static stability analysis program, which can run under linear and nonlinear condition, not only can it deal with continuous frame bridge, it can also calculate those which can be simplified as plane and spatial bar system. Reliability of this program has been inspected and verified compared with ANSYS results; its calculational accuracy can meet the requirements of actual project, so this program can be put into actual application.