Adaptable dual control systems. A comparative parametric analysis

Structural control through energy dissipation systems has been increasingly implemented internationally in the last years and has proven to be a most promising strategy for earthquake safety of the structures. The control concept is based on the integration of passive damping devices within the structure for the necessary energy dissipation and the elastic response of the primary system. Adaptable dual control systems (ADCS) presented in this paper, consist of tension-only bracing members with closed circuit and a hysteretic damper of steel plates. The implementation of ADCS in frame structures enables a dual function of the component members, leading to two practically uncoupled systems, i.e. the primary frame, responsible for the static vertical and horizontal forces and the bracing-damper mechanism, for the earthquake forces and the necessary energy dissipation. ADCS are investigated and compared in their energy dissipation behavior for three differing confi gurations of the bracing-damper mechanism. In all cases the hysteretic damper utilizes effectively the relative displacements between its connection joints, i.e. a bracing and a primary frame's member, through its own yielding deformations for the necessary energy dissipation. In the present paper parametric dynamic analyses of the SDOF system's responses have been performed, based on three representative international earthquake motions of differing frequency contents. A nonlinear link parameter, defi ned as the ratio of the stiffness to the yield force of the hysteretic damper, DR, characterizes the behavior of the controlled systems in each confi guration. Optimum DR values are proposed for each system confi guration in achieving high energy dissipation capacity, while preventing possible increase of the maximum base shear and relative displacements.