MITIGATION OF 3-DIMENSIONAL VIBRATION OF INCLINED SAG CABLE USING DISCRETE OIL DAMPERS - II - APPLICATION

The hybrid method developed in part I of this paper for three dimensio nal free and forced vibrations of an inclined sag cable with multi-pai rs of oil dampers is now applied to cables in a real cable stayed brid ge. Damper performance is evaluated in terms of the achievable maximum modal damping ratio and the possible maximum reduction of resonant re sponse of a cable in both in-plane and out-of-plane vibrations. Effect s of both cable properties and damper parameters, such as cable sag, c able inclination, damper stiffness, and damper location, are discussed . Optimum parameters for oil dampers, such as damper damping coefficie nt and damper direction, are sought within a range of practical intere st. The sensitivity study is also carried out to see the influence of small deviation of damper direction on damper performance. Finally, an investigation is performed to see how a proper arrangement of two pai rs of oil dampers can overcome insufficient damping ratio problem in t he first in-plane mode of a long cable due to frequency avoidance. (C) 1998 Academic Press.