Feasibility Study of a Novel Modal Decomposition Method for Low-Frequency Structure with Nonproportionally Distributed Rate-Independent Linear Damping

Compared with conventional linear viscous damping (LVD), rate-independent linear damping (RILD) mitigates floor response acceleration in low-frequency structures more effectively without compromising the control performance of displacement responses during long-period or low-frequency earthquakes. Although theoretical and experimental attempts have been made to overcome the noncausality of RILD devices and realize RILD using passive or semiactive devices, only a few studies have highlighted the impulse-response precursor and modal analysis method of multistory structures incorporated into RILD devices. This study investigated the impulse-response precursor of a noncausal RILD system and proposed a novel modal decomposition method for the structures equipped with nonproportionally distributed RILD devices. Additionally, real-time hybrid simulation was conducted to validate the effectiveness of the proposed modal analysis method and the feasibility of realizing ideal RILD using mechanical devices. This study is the first to demonstrate the differences between RILD and LVD devices in terms of controlling the modal responses of low-frequency structures and how RILD can lower the floor response acceleration more effectively compared to LVD.