Flutter Analysis Of Long-Span Suspension Bridge During Erection

With the increase of span, flutter stability has become a very important factor in design and construction of suspension bridges. Particularly in the early stage of construction, the stiffness of structure is less than that of the final state, which makes flutter critical wind speed drop sharply. By taking the Huangpu Southern Branch Suspension Bridge crossing Zhujiang River in Guangzhou as example, the flutter stability of construction stage and final state is discussed and some useful conclusions are drawn.Contents of this paper are as follows:First of all, based on the state-space method, the three-dimensional flutter equations are assembled, then computer program is compiled to solve the equations and two simple examples are taken to prove the program's preciseness; After then, the flutter critical wind speed of construction stage of Southern Branch Bridge is calculated, meanwhile the variation regularity of the flutter critical wind speed is discussed when structural stiffness and damp setting is different; With the increase of suspension span, the effect of nonlinear factor on flutter stability should not be overlooked, so flutter critical wind speed taking account of nonlinear factor of aerodynamic force and dynamic response is also calculated, relevant impact degree of different nonlinear factors are discussed too; At last, the influence of using secondary cable and non-symmetric construction on flutter stability is studied.