Experimental Research On Aerodynamic Performance Of Bridge Interfered By Rough Waves

The quality of large span structure of sea-crossing bridge is more and more light, the stiffness of the structure is more and more small and the damping of the structure is more and more low. This situation results in a sensitivity of bridge structure on the wind-induced effect more and more big, but also in strong wind conditions, often accompanied by the surging waves, which makes the bridge structure bridge structure in the wind and wave reaction more complex. If the bridge girder is near the sea surface, and the waves are fairly high, significant influence on wind flows and bridge aerodynamic performance may be incurred by waves. Generally speaking, the higher wave the lower deck i.e."low bridge and high wave", the aerodynamic effects are more obvious. However, the related investigations are rarely observed all over the world until now.The characteristics of wind flows and bridge deck aerodynamic performances are investigated by using wind tunnel tests in this report. The models of waves and bridge decks in wind tunnel tests are all rigid ones, i.e. the changes of waves and decks are ignored. The major contents of the researches are as follows:(1) The first chapter simply introduces the topic background, the research status and the content and significance of the article.(2) The second chapter briefly describes the basic principle of wave action. According to the principle and only considering the extreme wave under the condition of double wave, chooses two kinds of wave shape:sine wave and triangle wave.(3) The third chapter describes some related theories of bridge wind resistance. It mainly includes the near wind characteristics and the static and dynamic effect on bridge structure. It focus on average wind and fluctuating wind characteristics and three component coefficient of bridge section. It provides theoretical support for the later research on the characteristics of wind flows and bridge deck aerodynamic performances.(4) The forth chapter investigates the characteristics of wind flows under the condition of the wave interference by using wind tunnel tests:the object of study is sine wave1and triangle wave2. Keep the measuring points do not move in the wind tunnel and move the waves in the direction of the wind. At the same time, measure the points’ characteristics of wind flows and analyze the changing of the characteristics including three-dimensional fluctuating wind speed, attack angle and static pressure under different waveform waves in the wind field. The main conclusions are as follows:The flow field near region after wave is very complex, the parameters pulsation is large and the attack angle effect is obvious; Wind field characteristics in this region are greatly influenced by the waves, especially when the wave peak is near the station, the effect is very obvious, as well as the measuring point is closer to sea level, the aerodynamic interference effect more apparent.(5) The fifth chapter investigates the calm wind load effect of the girder under the condition of the wave interference by using wind tunnel tests:the objects of study are the two waveform and the cross section1. These papers mainly analyze the difference between with interference and without interference. What’s more we can get some useful information for wind resistance design. The main conclusions are as follows:Due to the aerodynamic interference wave, the three component coefficient is relatively higher than that of no interference condition. The impact on the three component coefficient is large, especially when the waves move to nearby area below the main girder, the significant effect is most. Generally speaking, the higher of the wave is, the steeper the wave is, the lower the girder wave is, the interference of wave effect is more obvious.(6) In this paper, the research methods and conclusions can provide useful reference for the wind-resistant design of large span cross-sea bridges.