Time Domain Buffeting Analysis Of Long-span Cable-stayed Bridges Based On Rational Functions

With the increasing development of the national economy and the continuous improvement of the level of bridge construction,the span record of modern long-span bridges is constantly being refreshed.The increase of span makes the bridge softer,less damping,more sensitive to the effects of wind,and the problem of wind-induced vibration of the bridge is increasingly prominent.Buffeting caused by stochastic wind is a limiting vibration.Although buffeting does not cause the destruction of structure,due to its high frequency of occurrence,the wind speed is relatively low,which can lead to structural functional obstacles such as causing fatigue failure of structure,affecting drive comfort,etc.,so buffeting analysis has become an increasingly important issue in bridge wind resistance analysis.In this thesis taking the SuTong Yangzte bridge as an example,the buffeting response of long-span cable-stayed bridges is studied in two different ways respectively in the time domain.The major work done in this thesis includes the following sections :(1)Introducing the characteristics and development history of cable-stayed bridges,pointing out the issue of wind resistance for long-span bridges,and reviewing the study of windinduced vibration problems of bridges briefly.(2)Simplifying the three-dimensional stochastic wind field of the cable-stayed bridge into three one-dimensional fluctuating stochastic fields distributed along the main girder and the tower as separate lines reasonably.WAWS method is used to simulate the time history of the stochastic wind speeds of the main girder and the bridge tower.(3)Time domain analysis of buffeting response of SuTong Yangzte bridge is carried out on the ANSYS platform.The wind load is treated as static wind force,buffeting force and selfexcited force.During the dynamic analysis,the effect of self-excited force is considered by using MATRIX27 element in ANSYS.(4)The self-excited force is processed in the time domain based on rational function,and two different state-space model are used to calculate the buffeting response of SuTong Yangzte bridge.The impact of self-excited force and aerodynamic transfer functions on the buffeting response of the bridge is discussed.