engleski

Efficiency of Seismic Damping Devices for Braced Structures

This paper describes the influence of dampers on structural response due to the dynamic earthquake load for a typical multistory steel structure with braces. Responses of different kinds of dampers are considered, depending on the excitation. The main purpose of structure isolation is to ensure elastic response of the structure while at the same time the areas of expected large plastic deformations and loss of input energy should be localized. Firstly, we consider viscous dampers which will be implemented in the models of earthquake bracing. Parameters defining damping force-velocity relations are varied in the numerical models. After the implementation of viscous dampers the Wen rheological model will be applied. With this kind of model we can control the initial stiffness of the damping device in elastic response and also the stiffness after yielding. This model describes more appropriately the response of real damping devices, but it is more complex for numerical analyses. Earthquake load comprises a wide range of frequencies significant for structures. In this paper this kind of load is modeled with a time history record of the real earthquake recorded at the Lexington Dam station during Loma Prieta earthquake in 1989. Additionally, as a simplification, the real earthquake excitation is replaced by a harmonic function with frequencies in the range of dominant eigen-frequencies. Forces and displacements obtained by conducted analyses are compared for different models in order to evaluate damper efficiency.

viscous damping; bracing; seismic load; force-displacement hysteresis

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