Wind-Induced Buffeting Analysis For Long-Sapn Highway Cable-Stayed Bridge

With the the development of design theory, and the advancement of building materials and construction techniques, modern long-span cable-stayed bridge is progressing towards extra long-span and extremely flexible. The problem of wind-induced vibration on bridge is prominently protruding day by day. Of all the wind-induced vibration problems, impact of buffeting on the safety of construction, the security and driving comfort at the using stage, and the fatigue of structural members can’t be neglected. Therefore, buffeting response analysis of long-span cable-stayed bridge is undoubtedly necessary. Currently, there’re two methods to analyze the response of buffeting on bridge structure:frequency domain analysis and time domain analysis. Each has its advantages, while the time-domain method is widely applied as its unique superiority that it can simulate the time history of vibration response on bridge structure, and simultaneously reflect the geometric nonlinearity as well as the aerodynamic nolinearity of structure.This thesis takes a long-span highway cable-stayed bridge as an engineering example, and conducts the linear time-domain buffeting analysis of long-span highway cable-stayed bridge at completed stage and typical construction stage(involving the largest double cantilever stage and the largest single cantilever stage).The major work of this thesis includes the following sections:1. Considering the structural features of long-span cable-stayed bridge, and combining the natural characteristics of fluctuating wind, the three-dimensional fluctuating wind field is properly simplified, and the corresponding simulating program is written to achieve the simulation of wind field on long-span cable-stayed bridge.2. The finite element method for the dynamic characteristics analysis of bridge structure is introduced. And the large general-purpose finite element analysis software ANSYS is used to establish the three dimensional finite element model and caculate the dynamic characteristics, providing basic model for time domain buffeting analysis.3. The static analysis of wind is conducted. Based on the theory of quasi-steady aerodynamic force proposed by Scanlan, buffeting force is caculated and loaded upon the established finite model for buffeting analysis in time domain. During the analysis, the influence of aerodynamic admittance function is considered by adopting the plate aerodynamic admittances function proposed by Liepmann, while the effect of self-excited force is considered by using Matrix27element in ANSYS in form of the element aerodynamic damping matrix and stiffness matrix. In additon, other factors such as wind velocity and attack angle are also taken into account.4. The work and results of this thesis are summarized, some conclusions gained from the study are given, and the problems to be resolved in further research are put forward.