Aerostatic Stability Analysis Of The Construction Phase For Long-Span Suspension Bridges

As the main type of the long-span bridges, suspension bridge is light and flexible. It is prone to aerostatic instability. Especially in the construction phase, girders were hinged temporarily, the stiffness was much more lower than that of the compeleted bridge so as the critical wind speed of aerostatic instability, and the speed may be lower than that of the aerodynamic instability.There is some engineering significance to study the problem of aerostatic stability of long-span suspension bridge.Firstly, the two kinds of theory of aerostatic stability are introduced, and the linear method prescibed by Wind-resistent Design Specification for Highway Bridge is used to calculate the critical wind speed of aerostatic stability and the nonlinear method is based on the finite element theory. Considering the nonlinearity of geometry and static wind loads, the calculation procedure of aerostatic stability of long-span suspension bridge is performed by finite element analysis software.Secondly, on the basis of the project The Fourth Bridge of Nanjing Yangtze River, main span 1418m, using the procedure above to make a full-process analysis on the aerostatic stability of the compeleted bridge and typical erection phases, considering the effect of different wind attack angles and combinations of aerostatic force factors, and to analyze the nonlinear behaviors of the structure under the critical wind speed.Finally, the effect of spatial distribution on wind speed of the aerostatic stability of the compeleted bridge and typical erection phases were discussed. It is showed that the aerostatic stability analysis is conservative regardless of the effect.