Wind Dynamical Analysis Of Han River North Bridge

With the development of the times and the economy, modern bridges are of the characteristics of large-span, low-rigid, light-weight and small-damp. So the bridge performance against wind becomes more and more impendence. This dissertation takes Han River Project as the research background, and chiefly studies the wind fluctuating performance of the structure. The main contents of this dissertation are as follows:(1) Summery is made on the present research state-of-the-arts about wind vibration on bridge and simulation of wind velocity nationally and worldwide.(2) The theories about wind load are presented, and particularly introduction is made on Monte-Carlo numerical simulation theory. Then a five-point-arch model is employed to validate the program on wind velocity simulation. It provides the foundation of the subsequent chapters.(3) Block Lanczos method is used to analysis the dynamic property of Han River Bridge, which includes following states: steel tube closure state, steel tube construction completion state and final completion state. A comparison is presented on the results, which mainly consist of frequencies and modes about all the three states. Finally, the calculated values are compared with measured value, the error is analysed and possible reasons are suggested.(4) Time-procedure analysis is employed in the fourth chapter. In order to examine the correctness of finite element calculation program, a tower model is set up; finally the program is validated by compare with the Chinese code value. Then this method is used to calculate the wind dynamic performance of Han River North Bridge at three construction states. By contrast, the results, which consist of displacement and stress distribution on each arch rib sections, as well as Gust response Coefficient, help us find the critical loading cases. In the end some suggestions are put forward to improve the situation.The research suggests that: the critical state is when the steel tube rib is closuring. At this time the bridge has the lowest basic frequency and stiffness, so the structural response under wind is very severe, even the stresses at some regions approach steel yield stress. When the whole steel tube rib construction is completed, stiffness of the structures achieve great enhancement, and the basic frequency became the highest in three construction states. At this time the wind respond decline much more. When the bridge is completed, the lowest basic frequency decreases, and the wind responde goes up relative to previous case.