Global optimization of locally installed adaptive negative stiffness amplifying damper in steel frames through rocking wall

Abstract

As a newly-developed damper system, negative stiffness amplifying damper (NSAD) is validated to be of high efficiency. Compared to the strategy of arranging multiple NSADs at multi-stories with much labor cost and sophisticated designing methodologies, this paper proposed a novel but simple strategy of using a single NSAD and a rocking wall (RW), where a global response control effect can be achieved. Seismic responses of typical steel frames with different NSAD and RW arrangement were first demonstrated in this study. Parametric study was conducted to find optimized design parameters of this system. Specifically, the larger the support stiffness the more significant displacement reduction can be achieved at the optimal damping ratios, which are in the range of 1.0–2.0 for all cases. To avoid excessive displacement amplification effect, absolute values of negative stiffness ratios not exceeding 0.3 are recommended. The optimal damping ratio is in the range of 10−0.5 to 10°.1 (i.e., 0.32 to 1.26). On the other hand, the larger the support stiffness and absolute value of negative stiffness, the more significant acceleration reduction can be achieved. Large adaptive NSAD displacement ratio, say larger than 1.5, should be avoided from the perspective of reducing structural displacement responses.