The Research On Geometric Nonlinearity And Stability Of Rigid Frame And Continuous Girder Bridge With High-pier And Long-span

In recent years, with the rapid development of the road and bridge in our country, as one of the main bridge, long-span rigid frame and continuous girder bridges constantly promoted and applied in our country., and in the direction of the high pier large-span development gradually. However, with pier slenderness ratio increases and the further extension of the main beam, displacement effects can’t be ignored, It is necessary to carry out the geometric nonlinear analysis. On the other hand, due to the structure gradually soft, stability of the bridge can’t be ignored.In this paper the characteristics, the domestic and foreign development situation and future development trend of long-span rigid frame and continuous girder bridge are briefly introduced. Described the development and the basic characteristics of geometric nonlinear theory, Compared the different points of U.L method and T.L method, derived the U.L of incremental equilibrium equation, While discussed the solution of several nonlinear equations. When we analysis the stability of bridges, usually two types of stability problems are taken into account, The first kind of stability problem is that branch point instability, The second kind of stability problem is that extreme point instability, he first kind of stability problem is the eigenvalue problem and is more convenient to solve. It’s critical load are similar to the limit load of second kind of stability. Therefore, the analysis of the first kind of stability problem has important engineering significance.Based on bridge of Aizhai, using the large bridge software MIDAS/CIVIL finite element model, take nonlinear theory as a foundation, analysis of geometric nonlinear effect on high pier cantilever state and the state of the bridge of the displacement and internal force, and compared to the result of linear conditions, analysis Influence of geometric nonlinear effects on bridges two states. Based on the stability theory, analysis the stability of high pier, cantilever state and the state of whole bridge. Consider influence on the stability of wind load, the strength of concrete, the high pier wall thickness and the single and double limb, and the results are discussed and analyzed, provide some meaningful guidance for the design and construction of similar bridges.