Flutter, Buffeting And Aerostatic Stability Analysis For Long-span Cable-stayed Bridges

Nowadays, cable-stayed bridge construction is developing into an extra long-span and flexible phase. The nonlinear time domain analysis method has therefore become a necessary choice and a developing trend for the refined analysis of bridge buffeting and flutter. In this paper, the status quo is reviewed about the research on buffeting and flutter vibration of the long-span bridge at the first place, and the last and the most a further research is done to resolve the problems and shortcomings in the time domain analysis. Based on the present theory on buffeting and flutter vibration, the practical flutter time domain analysis method of long-span bridges is developed. A full set of wind-resistance solution of bridge is put forward using ANSYS software. The dissertation is mainly focused on the following aspects:1. In this thesis, wavelet method is applied to the simulation of the stochastic wind field; performing the effective simulation of spatial stochastic wind field in order to consider the effect of the coupled vibration of the towers, cables and girders.2. According to the demand of wind-resistance analysis for the bridges, a full set of practical method of flutter time analysis is brought forward for cable-stayed bridges. It contains : (1) For the FEM model, the research determined the geometrical properties of complex thin-walled beams, replaced the triple-girder model with a new single spine girder model using ANSYS Beam18x element to check the shortcomings of the former one, and introduced the nonlinear cable element with 3 nodes and 13 DOFs to analyze the effects of cable vibration. (2) In the aspect of wind load, according to the practical principle, the paper introduced the quasi-steady theory of self-excited force formula of cables, transforming the Scanlan's self-excited force model to aerodynamic stiffness, aerodynamic damping and time integral item (It can be ignored), which can be simulated by MATRIX27 element of ANSYS software in order to take self-excited forces of cables and girders into consideration. (3) The thesis paper developed the buffeting analysis method in time domain, and performed the entire computation process of dead load to aerostatic stability analysis to buffeting analysis in time domain. The effects of geometric non-linearity and additive attack angle produced by aerostatic loads are included. The research firstly reckoned the instantaneous change in wind attack angle, and modified the aerostatic forces, self-excited forces and buffeting forces.3. Based on the ANSYS software, the bridge wind-resistance analysis program named WIND RESPONSE with ANSYS interface is introduced. It contains the module of time domain buffeting analysis, which makes bridge wind-resistance analysis more practical.4. In the research, the wind tunnel test of full-aeroelastic bridge model and nonlinear buffeting analysis in time domain of HangZhou bay bridge is done and some conclusions are obtained.5. By the method and program of this research paper, the buffeting analysis of Hang Zhou bay bridge...