Constant ductility inelastic displacement ratios for the design of self-centering structures with flag-shaped model subjected to pulse-type ground motions

Previous studies on the inelastic displacement ratio mainly focused on the structures with conventional hysteretic models. For the self-centering structure, a flag-shaped (FS) hysteretic behavior normally can be obtained. The research on the inelastic displacement ratio of this type of structure is however limited. The main purpose of this study is to investigate the inelastic displacement ratio of the self-centering structure with FS hysteretic model subjected to near-fault pulse-type ground motions for the seismic design of structures. The inelastic displacement ratio for the FS model (C-mu,C-FS) is calculated based on the nonlinear dynamic analysis of single degree of freedom (SDOF) systems subjected to 100 near-fault pulse-type ground motions. For comparison, the C-mu,C-FS spectra for far-fault ground motions are also calculated and discussed. The comparison results show that pulse-type ground motions lead to much larger C-mu,C-FS compared to far-fault ground motions, particularly for the acceleration-sensitive spectral region of near-fault pulse-type ground motions. Extensive statistical studies are further carried out to examine the influences of structural and pulse-type ground motion characteristics on the C-mu,C-FS spectra. Finally, a simplified equation is developed to estimate the inelastic displacement ratio for the design of self-centering structures under pulse-type ground motions.