The Akashi Kaikyo Bridge, whose main towers have already been completed, is now under construction. These towers are about 300 meters above sealevel, so that they are very flexible and their natural frequency i s lower than that of other towers of Honshu-Shikoku bridges. Consequently there arose an extremely important problem regarding how to control the vibration due to the wind. In the process of designing, a great variety of experimental and analytical studies were carried out. Based on their results, several types of damping device, such as TND, AND, and so on were installed on the towers to reduce the vibration. In this report, the outline of the vibration control design adapted for the towers will first be described, followed by the results of the field test and observation of the wind response performed on the towers under erection.
