Near‐fault acceleration pulses and non‐acceleration pulses: Effects on the inelastic displacement ratio

Abstract

Summary Near‐fault ground motions can impose particularly high seismic demands on the structures due to the pulses that are typically observed in the velocity time‐histories. The velocity pulses can be further categorized into either a distinct acceleration pulse (acc‐pulse) or a succession of high‐frequency, one‐sided acceleration spikes (non‐acc‐pulse). The different characteristics of velocity pulses imply different frequency content of the ground motions, potentially causing different seismic effects on the structures. This study aims to investigate the characteristics of the two types of velocity pulses and their impacts on the inelastic displacement ratio (CR) of single‐degree‐of‐freedom systems. First, a new method that enables an automated classification of velocity pulses is used to compile a ground motion dataset which consists of 74 acc‐pulses and 45 non‐acc‐pulses. Several intensity measures characterizing different seismological features are then compared using the two groups of records. Finally, the influences of acc‐pulses and non‐acc‐pulses on the CR spectra are studied; the effects of pulse period and hysteretic behavior are also considered. Results indicate that the characteristics of the two types of velocity pulses differ significantly, resulting in clearly distinct CR spectral properties between acc‐pulses and non‐acc‐pulses. Interestingly, mixing acc‐pulses and non‐acc‐pulses can lead to local “bumps” that were found in the CR spectral shape by previous studies. The findings of this study highlight the importance of distinguishing velocity pulses of different types when selecting near‐fault ground motions for assessing the nonlinear dynamic response of structures.

Effects of the Predominant Pulse on the Inelastic Displacement Ratios of Pulse‐Like Ground Motions Based on Wavelet Analysis

“…Ratios. e inelastic displacement ratios usually have a clear "bump" at the medium period region due to the influence of the predominant velocity pulse [19]. Previous studies have shown that the pulse period is an important parameter influencing the locations of the bump.…”

“…e pulse period and the pulse intensity are the two key parameters to describe the pulse features. Many studies have analyzed the effects of the pulse period [18][19][20], ground motion parameters [15,17,21], and structural characteristics, such as nonlinear behavior [20,22,23] and soil-structure interaction [24]. However, to the best of our knowledge, there is no study on the impact of pulse intensity.…”

Effects of near‐fault acceleration and non‐acceleration pulses on pounding between in‐plan irregular fixed‐base and base‐isolated buildings

“…8,9 Yet, amplification of the torsional response is observed when the pulse period is close to the fundamental torsional period of the structure 10 and orientation of the strongest velocity pulse can occur along a direction different from the strike-normal and strike-parallel ones. 11,12 Nowadays, time-frequency domain [11][12][13][14][15] and response spectrum 16,17 methods are available in the literature to detect pulses in ground motions and, more recently, to retain the impulsive effect of the original ground motion on structures. 18 At the same time, pulse indicators are proposed to characterise pulse-like and non-pulse-like near-fault earthquakes.…”

“…Attention is focused on the pulse-type and non-pulse-type near-fault earthquakes, 11 identifying potential pulses in the acceleration time-histories by means of an automated algorithm. 13…”

Quantitative Identification of Pulse‐Like Ground Motions Based on Hilbert–Huang Transform

“…is recognition method greatly improves the efficiency of recognition [19]. For the effect of pulse on the structure, some scholars further divided the velocity pulses into distinct acceleration pulses and nonacceleration pulses according to the impact of earthquake on the structure and the content of different frequency components of ground motion [20].…”