Constant Ductility Site‐Specific Yield Point Spectra for Seismic Design

Abstract

Displacement-based seismic design (DBSD) is an iterative process because the strength and stiffness of a structure are needed to be adjusted in order to achieve a specific performance level, which is extremely inconvenient for designers in practice. Yield point spectra-based seismic design is treated as an alternative design method in which yield displacement as a basic parameter will not lead to an iterative process even though the lateral strength or stiffness of a structure changes during the whole design process. Along this line, this study focuses on investigating the yield point spectra (YPS) for structures located at different soil sites. YPS are computed for EPP systems under 601 earthquake ground motions. YPS for four soil sites are quantitatively analyzed by considering the influence of the vibration period, ductility factor, damping ratio, postyield stiffness ratio, and P-delta effect. The results indicate that compared with the effects of the damping ratio, the effects of the postyield stiffness ratio and P-delta effect on YPS are more profound. Finally, a prediction equation is proposed accounting for four soil sites and six ductility factors.

Constant-ductility energy factors of SDOF systems subjected to mainshock–aftershock sequences

“…This trend is confirmed by the outcome of relevant studies (e.g. Ji et al, 2019), in which the residual displacement ratio was systematically evaluated for structural systems located on soft soil sites. Moreover, such a trend becomes more evident when the bilinear system is anticipated to experience significant inelastic deformations, that is, μ = (5).…”

“…For the entire period range, the mean energy factor of the bilinear systems was found to be influenced by the post-yield stiffness and its low values lead to increased seismic demand in terms of g. This trend is confirmed by the outcome of relevant studies (e.g. Ji et al, 2019), in which the residual displacement ratio was systematically evaluated for structural systems located on soft soil sites. Moreover, such a trend becomes more evident when the bilinear system is anticipated to experience significant inelastic deformations, that is, m = (5).…”

“…The use of those demand indices is quite broad since they constitute an intrinsic part of several contemporary schemes being used either for design or assessment purposes. Stemming from the rather basic, though widely used, strength reduction factor (Newmark and Hall, 1973) and the ductility factor (Park, 1989), numerous relevant indices of varying complexity have been proposed to characterize the inelastic response of structures accounting for force- and/or displacement-related seismic demand (Ji et al, 2019; Katsanos and Vamvatsikos, 2017; Tjhin et al, 2007; Tsiavos and Stojadinović, 2019). For example, the yield displacement was selected as a demand index for contemporary seismic design (Ji et al, 2019; Tjhin et al, 2007) and assessment (Tsiavos and Stojadinović, 2019).…”