Recent studies predict that Nankai-Trough earthquake to be a huge one. As a mitigating measure, passive dampers are widely adopted to control structural vibrations of buildings. These devices work effectively against the inter-story shear deformation of the building frame. In contract, they are less effective when building deformation is mainly characterized as flexural or bending deformation. It is, therefore, important to study the effective damper deformation in order to evaluate vibration control performance. This paper aims to clarify the relationship between the effective damper deformation and damper ductility demand when the damper works effectively.
