Abstract
SUMMARYViscous fluid dampers have proved to be effective in suppressing unwanted vibrations in a range of engineering structures. When dampers are fitted in a structure, a brace is typically used to attach them to the main structure. The stiffness of this brace can significantly alter the effectiveness of the damper, and in structures with multiple dampers, this can be a complex scenario to model. In this paper, we demonstrate that the effects of the brace compliance on the damper performance can be modelled by way of a first‐order filter. We use this result to formulate a procedure that calculates the stiffness required by the supporting brace to provide a specified effectiveness of the damping action. The proposed procedure assumes that viscous dampers have been sized in a previous design step based on any optimal methodology in which, as is usually the case, the presence of supporting braces and their dynamic effects were neglected. Firstly considering a one degree‐of‐freedom system, we show that the proposed method ensures a desired level of damper efficiency for all frequencies within a selected bandwidth. Then the analysis is extended to the case of multi‐degree‐of‐freedom systems to show that the design criteria can be applied in a straightforward and successful manner to more complex structures. © 2014 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.
Highlights
The idea of incorporating damping devices into a structure that can absorb a considerable portion of the vibration energy has been used for many decades [1,2,3]
This paper focuses on the design of supporting braces for structures provided with linear viscous fluid dampers
We propose a new method for selecting brace stiffnesses
Summary
The idea of incorporating damping devices into a structure that can absorb a considerable portion of the vibration energy has been used for many decades [1,2,3]. The authors concluded that a ratio between the damper parameters and braces stiffness approximately in the range 1:0–1:5 and a ratio between the braces and storey stiffness in the region of 10 are recommendable for near-optimal solutions Their formulation is based on the study of the steady-state harmonic motion of an SDOF oscillator fitted with a brace–damper system at its undamped natural frequency only. We use the first-order filter observation to determine the stiffness required by the supporting brace such that the resulting brace–damper assembly will behave with a desired level of efficiency within a predefined frequency bandwidth By adopting this approach, we believe that this simple method can be used as an additional tool, which is complementary to conventional damper design strategies.
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