A study on countermeasures against wind-induced cable vibrations in cable-stayed bridge by changing vibration modes: 3rd report, design method of a control device

In order to suppress vibrations of stay cables in cable-stayed bridges, the authors developed a new vibration reduction method called "Changing vibration modes method" using a permanent magnet. The authors have confirmed its effectiveness in former reports by both theoretical analyses and wind tunnel tests. In second report, the authors analyzed cable vibrations by taking account of only an unstable mode and clarified how the design parameters such as a gap and magnetic force affect the control efficiency. In this report, accuracy of the analysis is further improved by introducing the higher modes effects as an "equivalent aerodynamic damping". Then, a design procedure of the parameters is proposed on the basis of the improved analysis, and its validity is shown by wind tunnel test results.