Strength reduction factor for inelastic-displacement estimation and design of self-centering viscous-hysteretic systems.

This study focuses on developing strength reduction factor R μ spectrum, a maximum inelastic displacement (MID) estimation method and a displacement-based design method for single-degree-of-freedom (SDOF) bilinear structures with self-centering viscous-hysteretic devices (SC-VHDs). The effects of design parameters on R μ spectrum are statistically investigated under near-fault pulse-like ground motions (NFPG) and far-field ground motions (FFG), and its prediction formula is fitted according to the statistical data. Following proposed R μ spectrum, a MID estimation method and a performance-based design method are proposed, respectively. Next, three SC-VHD frames are designed step-by-step to verify the proposed design method, and then their MIDs are calculated step-by-step to validate the MID estimation method. Finally, a risk assessment is conducted on a SC-VHD frame and a conventional frame to compare their collapse performance and the performance exceeding 0.2% residual drift in the probability framework. The results indicate that R μ spectrum is primarily affected by the ductility ratio, period and viscous damping ratio, while the parameters of ring springs have little effect on it. R μ spectrum under the NFPE is significantly lower than that under the FFE except for periods from 0.2 s to 0.6 s. The R μ spectrum formula and the MID estimation method both have errors that are typically less than 10%. The designed SC-VHD frame can achieve the target performance, and its probability of collapse and exceeding 0.2% residual drift in a period of 50-year is significantly smaller than that of the conventional frame. • Strength reduction factor spectrum is developed for self-centering viscous-hysteretic systems. • A maximum inelastic displacement estimation method is proposed. • A displacement-based design method is proposed. [ABSTRACT FROM AUTHOR]