Nonlinear Analysis Of Spatial Stability Of Reinforced Concrete Arch Bridge

Stability can be divided into two forms, which are the first class stability and second class stability. The first instability is also called linear elastic buckling, and the second category is also called extreme point buckling instability.Tied arch bridge not only has a larger capacity as normal arch bridges but also has the ability to adapt to a variety of foundations. Arch has advantages such as high capacity, easy construction, good economic returns, etc. This structure in the bridge construction has been widely applied. But as bending structures, stability of the arch must be considered seriously in the design calculation process. In recent years, with the use of new technologies and new materials and the span of arch increasing, stability problem has become particularly prominent.In this paper, Arch development process and the status of tied arch bridge Research, and Theory and nonlinear finite element method, and Arch stability theory and the calculation of stability are elaborated. In this paper, Based on Lu Yu Bridge, The overall stability of the arch and the whole arch of the bridge parameters on the stability was Discussed and Analyzed. The main work is as follows:1. Using large-scale finite element software ANSYS Software, This article established the stability of the entire bridge model of Lu Yu Bridge. When establishing the bridge model, this article disperses real bridge into spatial frame structure. Link8 element is be used to simulate boom. Space beam element Beaml88 is be used to simulate rib, tie beam, support beams and cross ribs. Pick arm and the other sidewalk, and two bridge deck pavement are converted into line load uniformly distributed in both sides of the beam line. The total number of nodes for the full-bridge is 576 and is divided into 382 units.2. By linear elastic theory, in the dead load and full load four trains road covered bridge in the state, the eigenvalue stability of entire bridge of Lu Yu is calculated. And get the first safety factor. By geometric nonlinear theory, geometric nonlinear buckling analysis has been done, and got the safety factor and the buckling mode under different conditions.3. By Concrete Association with the European Standards (CEB-FIP Mode code) nonlinear relationship between stress and strain of material and geometric nonlinear theory, writer does the dual nonlinear analysis to calculate the stability of Lu Yu Bridge. And stability coefficients were obtained in various operating conditions and failure modes. The double nonlinear buckling analysis showed that including in the material nonlinearity; the entire bridge has a larger safety factor reduction. Relative eigenvalue analysis, the reduction rate is about 28% to 49%. Nonlinear stability analysis of the stability safety factor well below the elastic eigenvalue buckling analysis of the value.4. Five factors including the number of horizontal brace, rib roll angle, wide-span ratio, initial geometric imperfections, and span ratio on the stability of the bridge phase space are discussed. And looking into the mechanism of the influence of each parameter. Analysis shows that:Arrangement and stiffness of the crossbars directly affect the overall stability of double-rib arch bridge. The inner rib angle should not be too large, and selecting the bridge must be considered the lateral stability and ultimate strength of the opposite. With the wide-span ratio decreases, the tied arch bridge down the stability of the main arch. Defects in the same initial conditions, the effect of double nonlinearity on the stability safety factor have greater impact than the simple geometric nonlinear large Double nonlinear structure will significantly reduce the ultimate bearing capacity. Span ratio has greater impact on the stability of the structure. In practical engineering, designers can choose the right parameters to improve the reinforced concrete arch bridge stability.5. In this paper, based on research results at home and abroad, aim to the nonlinear stability of reinforced concrete arch bridge, conclusions which are summarized by the actual engineering calculation can provide theoretical guidance on similar bridges.