Aerostatic And Aerodynamic Stability Of Super-Long-Span Suspension Bridge

Due to small stiffness and low damping, super-span suspension bridges are susceptible to wind. As well as the flutter stability, the aerostatic stability is also a governing factor in design and construction of super-long-span suspension bridges, considering that the critical wind velocity for the aerostatic instability may be lower than the flutter velocity.In this thesis, the aerostatic stability and flutter stability of a CRFP-cable suspension bridge with main span of 3500m is studied, which can provide some references for wind-resistant design of super-long-span suspension bridges.Firstly, the methods of aerostatic stability analysis and flutter stability analysis for super-long-span bridges are reviewed.Then, the method that combines increment and double iteration is used to carry out nonlinear aerostatic instability analysis. The effect of nonlinearity, initial attack angle, cross cable and girder section are discussed. The mechanism of aerostatic instability for super-long-span suspension bridges is explored.At last, the multi-mode flutter analysis of the bridge is performed by the state-space method. Comparing the results of three different flutter analysis methods, it is found that multi-mode flutter analysis is more practical and precise. The effect of stiffness reduction of stiffening girder and structural damping are discussed in detail. The study also shows that flutter stability in erection phase of super-long-span suspension bridge can be greatly improved by cross cable.