Placement and tuning of resonance dampers on footbridges
Author(s): |
Stehen Krenk
Anders Bronden Anders Kristensen |
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Medium: | conference paper |
Language(s): | English |
Conference: | Footbridge 2005 (Second International Congress), Venezia, 06-08 December 2005 |
Published in: | Footbridge 2005 |
Year: | 2005 |
Abstract: | The placement and tuning of multiple tuned mass dampers is discussed with reference to the newly designed Langelinie Footbridge, presently under construction in Copenhagen. First the principles of resonance dampers are briefly reviewed, and a novel result for the calibration is presented. It has been shown that classical frequency tuning combined with minimization of the relative motion of the damper mass leads to an increase of the damping relative to the classical procedure with about 12 pct. The two design approaches: i) minimum resonance for frequency dependent load, and ii) robustness against resonance by sufficient damping ratio, are discussed. A simple two-step procedure is presented for design of multiple dampers on footbridges: first the properties of tuned mass dampers for the relevant free vibration modes are estimated by generalizing the simple basic equations to modal vibrations, and then the parameters are fine tuned by vibration analyses including the suspended masses from the resonant dampers for the other modes. Usually a single correction is sufficient to obtain equal damping in the combined system. |