Swing story-lateral force resisting system connected with dampers: Novel seismic vibration control system for building structures

This study proposes a vibration control system consisting of a swing story subsystem, a lateral force resisting subsystem, and connecting dampers. The swing story subsystem comprising hinged columns connected to continuous beams is employed to resist the gravity load, and perimeter moment-resisting frames the lateral force. Dampers are adopted to transfer lateral forces between the two subsystems and are used to dissipate seismic energy. The main characteristic of the system is that both the fundamental and higher-mode responses can be reduced remarkably compared with conventional moment-resisting frame structures. This paper establishes equations of motion of the proposed swing story control system, and the dampers are optimally designed by a multiobjective optimization algorithm with the combination of the stability maximization and H2 criteria. To avoid instability of the flexible swing stories, sufficient stiffness is required for the dampers, and buckling analysis is thus conducted to determine the required minimum stiffness. Excellent vibration control effects of the proposed system are verified through numerical analyses of three-story and nine-story benchmark structures.