Optimization On Arch Axis And Stability Analysis Of Special-shape Arch Bridge

Along with the development of the society, bridge structure does not only satisfy the function of traffic but also is a structure of space art in the society. Bridge style becomes more rich and varied because people pay great attention to bridge aesthetics increasingly. Some novel special-shape arch bridge have been coming to people base on the traditional arch bridge. Generally speaking, compared with the traditional arch bridge, the special-shape arch bridge pursue the visual beauty and inevitably will have to sacrifice some of the rationality of the structure stress at the same time. It will lose individuality and characteristic of the bridge design according to emphasis of reasonable of structure stress. It masks the bridge design more reasonable that find a balance between mechanics and aesthetics of bridge structure.Tong-Tai bridge, over Zhang Jia-kou Qing-Shui river is a special -shape arch bridge with arch oblique cross the main girder. The arch's span is 180 m and the rise-span ratio is 0.3451; The main girder's span is 190 mand the plane radius is 600 m. Base on the project, solving the reasonable axis of arch, optimizing the reasonable approximate axis of the arch, and analysing the stability of the structure, the treated main items include:(1) Studying the method to solve the reasonable axis of arch. There are two methods in this paper. Method one, the second order differential equation, which solved by numerical method; Method tow, the approximate truss numerical method. There is an additional bending moment at anchoring point on the arch whose hangers are collocated oblique and not on the arch axis (such as Tong-Tai bridge). Base on the approximate truss numerical method, it proposes another modified approximate truss numerical method to solve the problem of additional bending moment. This method is practical and useful.(2) Optimizing the axis of arch bridge. Base on Tong-Tai bridge on Zhang Jia-kou Qing-Shui river, this paper solves the reasonable approximate axis of the arch by using modified approximate truss numerical method. According to the final finished bridge state, optimize the axis of the arch by using several single node loads to make the arch's stress more reasonable. The difference between maximum envelope stress of both side of arch is 0.093MPa. This method is simple and useful.(3) Analysing the stability of the structure. Studying on the stability theory of long span arch bridge. It includes in-plane buckling and lateral buckling, analytical method and numerical method, follower force effect, and finite element method analysis of first kind stability problem including linear elastic analysis and geometric nonlinear analysis. It solves the stability problem of Tong-Tai bridge, using the professional bridge program TDV RM2006. The whole structure has good stability because of big cross section and follower force effect.