In the design of long span bridge, it is important to consider the dynamic response of a bridge to the wind load including the aerodynamic instability such as flutter phenomena, vortex-induced oscillasion and buffeting phenomena.
In this thesis, the experimental study to the response of the 2-D rectangular sections is conducted varing the width to depth(B/D) ratio. Based on the results obtained, the study to response of the box-girder sections according to the different shapes is also performed. By using the elastically supported model, behaviors related to velocity of wind, surface steady pressure and surface unsteady pressure etc. are measured. The response dependes principally upon the B/D ratio and the angle of attack in the rectangular section. Aerodynamic motions are observed in galloping when the B/D ratio is rather than or equal to 2.5, but in unstable flutter when the B/D ratio is greater than 2.5 because of the wake bubble and flow reattachment on the side face. Moreover, it is found that the aerodynamic stability of the box-girder sections is influenced by the geometric shape and the angle of attack. For all sections, the aerodynamic stability is increased as the seperation of flow is restricted and decreased as the angle of attack is increased.
