Mitigating the Stay Cable Vibration under Deck Excitation

The mitigation of in-plane stay oscillation in cable-stayed bridges is commonly addressed by placing an external mechanical damper, linear or nonlinear, on each stay cable. The current widely used by researchers in the theoretical model assumed that the dampers are fixed outside of the deck, is not reasonable to consider the bridge deck-cable-damper coupled vibration impact. Hence, in consideration of the impacts of coupling, through theoretical analysis amended to establish an accurate stay cable coupled vibration damper model, is a comprehensive understanding of deck-cable-damper coupled vibration damper characteristics to determine a reasonable external damping parameters of the fundamental guarantee. In this paper, a new analytical model is developed in order to investigate the coupling effects among deck-cable-damper, which have thus far been omitted from previous models of parametric excitation of inclined cables. To investigate affection of modal damping of the cable-DAD system subject to the coupling motion of DAD with deck, the normalized damping ratio is numerically calculated by a trial-and-error process of the normalized damper coefficient for the different support assumption conditions. The result shows that the external damping c_v should be increase deeply to provide the same non-dimensional modal damping, and hence overestimating its value steadily in the old model, this matches well with the actual occurrence in bridge engineering. Our study reflects the importance of such effects.