Effect of Vibration Reduction of Suspension Typed Tuned Mass Damper with Double Pendulum Lengths and Analysis of Footbridges on Pedestrian Induced Vibration
Date Issued
2015
Date
2015
Author(s)
Jhang, Jing
Abstract
A simple pendulum consists of a mass which hangs from a string and fixes at a pivot point. By applying Newton''s secont law, the equation of motion for the pendulum could be obtained. In this study, the nonlinear and linear equation of motion of a pendulum and pendulum-structure system subjected to external forces is derived. The time history analysis is simulated using state-space method. The amplitude of angular displacement is small so that the equation of motion could be reduced as a simple harmonic equation of motion. This assumption is confirmed by comparing the time history analysis, frequency sensitivity analysis, and design parameter sensitivity analysis results. Passive tuned-mass dampers (TMDs) are a very efficient solution for the control of structural vibrations subjected to long-duration, narrowband excitations. In this study, a suspension typed tuned mass damper with double pendulum lengths is proposed. The pendular mass is suspensed by cables and linked with viscous dampers. The main advantage of the proposed double pendulum lengths TMD is that, it allows control of structural vibrations in both principal directions with different natural frequencies. Numerical results show that, under various wind force excitations, the level of response reduction achieved by the proposed double pendulum lengths TMD is much better than a single pendulum lengths TMD in both directions. Vibration behavior of the footbridge due to pedestrian loading has arised the attraction in these years. The cases of London Millennium bridge, Toda Park bridge in Japan, etc… show that the dynamic action of pedestrian loading should be taken into consideration in design procedures. According to those European footbridge design codes and some relative researches, the method of modeling pedestrian loadings acting on the footbridge is accomplished. Analysis and design procedures of a practical footbridge vibration reduction by TMD is performed in this study. These evaluation methods of footbridge vibration reduction are proposed for engineering applications.
Subjects
tuned mass damper
bidirectional
nonlinear
Footbridges vibration
Type
thesis
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