Study On Full-modal Coupled Flutter And Buffeting Of Long Span Bridges

Nowadays, with the suspension bridge developing toward super long-span and extremelygentle, the wind-included vibrations of bridge structure have become more and more serious.Bridge buffeting is inevitable, during the construction phase and the operational phase, whichnot only relates to the safety during the construction phase, but also affects the fatigue life of thestructure and the driving comfort during the operational phase. The existing buffeting analysismethods of bridge structure can be divided into frequency domain and time domain. Thebuffeting analysis method in frequency domain has been widely used because it is simple,practical and effective, but it ignores geometric nonlinearity and nonlinear characteristic ofaeroelastic dynamic. In recent years, with the development of computer technology, thebuffeting analysis method in time domain has been applied by more and more researchers,because it can reflect the schedules of structural vibration and include geometric nonlinearityand nonlinear characteristic of aeroelastic dynamic. In China, the majorities of long-spansuspension bridges are located on the southeast coastal areas, which are suffered from strongtropical storms and typhoons in different degree. The study of bridge buffeting is particularlyimportant.In this thesis, taking the Xihoumen Bridge as a project example, the bridge buffetingduring the operational phase is studied, based on filed monitoring. And field monitoring datasand the numerical results are compared. The main research content includes the following:(1) The bridge structure buffeting histories and current status are reviewed; the theories offrequency domain and time domain for buffeting analysis are discussed deeply.(2) The turbulent characteristics of the Meihua typhoon wind are analyzed, including:average wind speed, average wind angle, turbulence intensity, turbulent integral scale,turbulence power spectrum, spatial correlation of turbulent wind, time-frequency characteristicsof turbulent wind, in order to simulate the wind loads more accurately.(3) The finite element model of the Xihoumen Bridge is established in ANSYS, throughthe finite element method. The dynamic characteristics of Xihoumen Bridge are analyzed,including: static analysis of finite element model of the Xihoumen Bridge, finite element modelupdating biased on field measurement frequency and mode, modal analysis of finite elementmodel of the Xihoumen Bridge.(4) The grider of the Xihoumen Bridge buffeting response is analyzed through complete quadratic combination in frequency domain method (CQC method). And field monitoring datasand the numerical results are compared. At the same time, factors (aerodynamic self-excitedforces, aerodynamic admittance function, spatial correlation) that influence the calculations ofbuffeting response are analyzed.(5) Three-dimensional fluctuating wind field of Xihoumen Bridge is simulated byharmonic synthesis method, in order to get the turbulent wind schedule of each node (includinglongitudinal and vertical). Turbulence power spectrum and spatial correlation of turbulent windsimulated are tested.(6) The grider of the Xihoumen Bridge buffeting response is analyzed through completequadratic combination in time domain method. And field monitoring datas and the numericalresults are compared, including the schedule of buffeting response and the power spectrum ofbuffeting response, in order to determine the effectiveness of buffeting analysis in frequencydomain method.