The Analysis Of Nonlinear Stabilization For High Pier And Long Span Continuous Rigid Frame Bridge

In the recent years, with the development of Science & Technology and transportation enterprise, long span continuous rigid frame bridge with thin-walled high piers is commonly built in China, owning to their advantages on economy and construction. However, the stability problem of the bridge, especially in the stage of cantilever construction is more remarkable. Based on Fengshihe Bridge of Jishao highway in Henan province, this thesis focuses on the nonlinear stability of continuous rigid frame bridge with high Piers during the construction of cantilever, by use of finite element program ANSYS.Firstly, the thesis reviews the investigation development on stability of bridges and the existing status; Then two types of basic theories of stability about bridge structure are introduced and the thesis indicates most stability problems come up against in practice belong to the second type stability problem; The nonlinear FEM compution method and process of the nonlinear stability problem are studied furtherly. Subsequently by utilizing the current finite element program ANSYS, two types of finite element models, i.e., beam model and shell model, are established for the nonlinear stability comparative analysis in the cantilever construction stage.Secondly, structure dynamic characteristic analysis on two models under the effects of grativity is performed, and the similar modes indicate that the models are reliable. In analysis of structure stability, the eigenvalue caculated by general method adapts to the case that constant load and live load are variable at the same time, but because constant load is invariable, the above result is conservative. In regard to this, live load is applied by iterative method till the eigenvalue is equal to one in the thesis. The eigenvalue caculated by this method of applying load is more precise.At last, the second type nonlinear stability analysis on cantilever constructon is performed. The first order displacement eigenvector of buckling from linear stability analysis is regarded as initial geometry defect, and compares results whether or not initial geometry defect is considered. The conclusion can be reached that the influence of initial geometry defect on ultimate bearing capacity of structure is weak. But after comparing the result from the case of only geometric nonlinearity with that from the other case of geometrical and material nonlinearity simultaneously, the conclusion is come to that material nonlinearity have a strong influence upon ultimate bearing capacity of structure. Therefore, the suggestion...