Conference Paper Analytical Study of Viscoelastic Dampers Subjected to Long-Duration Excitations Considering Heat Generation and Transfer

OSABEL, DAVE M  ,  Osabel, Dave M  ,  佐藤, 大樹  ,  Sato, Daiki  ,  笠井, 和彦  ,  KASAI, KAZUHIKO

It is well-known that viscoelastic dampers are effective passive energy dissipation devices for earthquake and wind loadings. The energy dissipated is converted into small amount of heat; consequently, softening the viscoelastic material as temperature rises. In a typical earthquake, the temperature rise is barely affecting the damper. However, heat generation, conduction and convection can occur and control the rise of temperature when dampers are subjected to long- duration loadings such as wind. Though these effects were observed in experiments and full-scale measurements, complex relationship of several parameters makes it difficult to predict the damper behavior. This paper presents the previously proposed analytical methods that considered the effects brought by long duration loadings. First method combines three-dimensional heat transfer analysis and static analysis using common finite-element model of the damper to estimate its dynamic properties. The second method combines one-dimensional heat transfer analysis and viscoelastic constitutive rule using fractional time-derivatives of stress and strain, and it calculates step-by-step the force-deformation time histories of the damper. Using these methods, dampers of different configurations were investigated; as well as the effects of ambient temperature. This paper also presents the modified algorithm for calculating fractional time-histories of stress and strain by approximating a uniform strain distribution in the viscoelastic material at every time-step.

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