Large Span Steel Box Irregular Shape Arch Bridge Internal Force Analysis And Stability Study

Arch bridge is a bridge form with a long history, with the development of science and technology, based on the aesthetic considerations make modern arch bridge is developing towards large span, complex system, so as the main compression artifacts, the stability of the arch bridge is becoming more and more outstanding, become the main factor of restricting its development. The arch rib in the pressure at the same time also absorb a certain amount of bending moment, torque and shearing force, force form complex, thus in the process of construction and operation stability problems of the more prominent. This paper, taking a "M" shape different arch bridge in shenyang as an example the main research content is as follows:(1)、the analysis of bridge structure system, according to the actual circumstance of the bridge structure features and professional software MIDAS CIVIL bridge structure is adopted to establish the whole bridge finite element model, and the actual construction process simulation. Through the static analysis of the bridge with the state of the bridge, the bridge internal force, stress, displacement and derrick process of design calculation, finally ensure the smooth progress of bridge construction, and into the bridge after high-speed driving comfort and safety.(2)、the whole bridge internal force calculating and analyzing the stress and displacement of arch rib each section by stress and the steel beam combined with the junction of bending shear change. Analyzed the change and the displacement of members of the whole bridge derrick mechanical characteristics and the safety factor of the derrick.(3)、two types of stability analysis of the whole bridge, in which the first kind of stability for the eigenvalue problems, to practical engineering has important guiding significance. But its theoretical significance is very big, but in practice due to the structure of the initial defects and problems existing in the material itself, studies its theoretical significance is not big, therefore, to the second category of buckling analysis, and so on the analysis to consider the influence of geometric nonlinearity, such ability can concluded that the results of engineering has a realistic significance.This paper, taking a "M" shape arch bridge as the engineering background, through the first kind of stability analysis, studied the structural parameters affect the stability of the bridge, to master the various structural parameters on the effect of arch bridge stability. Also number of Ⅱ arch rib on the stability of the geometric nonlinear stability analysis. The results show that the stability of the whole bridge safety stock is higher, the stability of weak position for Ⅱ arch rib, the arch rib because of the existence of arch cross brace so instability forms mainly in-plane instability, working under the action of a stability coefficient is 38.73. A few not line in the complex system bridge great influence factors on the stability analysis, must be considered. Through calculation and analysis:with the bartender is proportional to the force, including the confirmed the existence of the force on the stability of the structure is very useful. The paper of the alien arch bridge of stability analysis, results show that the stability of the construction process to achievesafety standards.(4)、Several factors influence the stable of the special-shaped arch bridge are analyzed, including the spacing between the sizes of derrick, the influence of rise-span ratio and the influence of the Angle of the arch rib, calculation and analysis results show that the stability factor of the arch rib and showed a trend of decline, with the increase of derrick spacing increases derrick spacing can save material, reduce the project cost, but is decreased the stability of the structure, so the design should be considered when choosing a derrick spacing, the rise-span ratio was between 0.3 and 0.5 for optimal, when rise-span ratio greater than 0.5, the structure stability coefficient increases accordingly. In arch rib Angle 0°-16° stability increases accordingly,16° after basic remain unchanged. So when choosing Angle should be according to the actual need to select the optimal Angle.