Automated classification of near‐fault acceleration pulses using wavelet packets

Chang, Zhiwang; Luca, Flavia De; Goda, Katsuichiro

doi:10.1111/mice.12437

Cited by 30 publications

(21 citation statements)

References 51 publications

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“…Using a new algorithm 26 for classifying acc-pulses and non-acc-pulses, this study first discussed the characteristics of the two types of velocity pulses that are considered to be caused by forward directivity and then the effects on the inelastic displacement ratio (C R ) were investigated. The main findings are as follows:…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, the dataset consists of 320 ground motions each with two horizontal components, which are the same as those used in Chang et al 26 They were recorded in earthquake events with moment magnitude (M w ) ≥5.5 and at least one of the two horizontal components has PGV value of larger than 30 cm/s. Specifically, the dataset consists of 320 ground motions each with two horizontal components, which are the same as those used in Chang et al 26 They were recorded in earthquake events with moment magnitude (M w ) ≥5.5 and at least one of the two horizontal components has PGV value of larger than 30 cm/s.…”

Section: Seismological Features Of Acc-pulses and Non-acc-pulsesmentioning

confidence: 99%

“…For classifying acc-pulses and non-acc-pulses, two main steps are required, see Figure 2. More details about this algorithm can be found in Chang et al 26 The main procedures for performing such a classification are as follows: 1. In the first step, for a velocity time-history shown in Figure 2A, the wavelet packet transform (WPT) is used to remove the high-frequency content.…”

Section: Pulse Classification Algorithmmentioning

confidence: 99%

“…Yet after examining their acceleration time-histories more carefully, the two dominant velocity pulses are observed to contain significantly different frequency content. In this regard, a new algorithm 26 for automatically classifying acc-pulses and non-acc-pulses can be implemented to perform a comparative study to reveal how the velocity pulses of different characteristics may affect the inelastic response of structures. The velocity pulses having different frequency content can cause different impacts on the structures.…”

Section: Introductionmentioning

confidence: 99%

“…24,25 No systematic statistical analyses have been carried out. In this regard, a new algorithm 26 for automatically classifying acc-pulses and non-acc-pulses can be implemented to perform a comparative study to reveal how the velocity pulses of different characteristics may affect the inelastic response of structures. Following the compilation of the two groups of velocity pulses, the characteristics of acc-pulses and non-acc-pulses are studied, and the effects on the inelastic displacement ratio (C R ) are systematically investigated.…”

Section: Introductionmentioning

confidence: 99%

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

Chang

Luca

Goda

2019

Earthq Engng Struct Dyn

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Seismological Features Of Acc-pulses and Non-acc-pulsesmentioning

confidence: 99%

Section: Pulse Classification Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Chang

Luca

Goda

2019

Earthq Engng Struct Dyn

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Automated parameterization of velocity pulses in near‐fault ground motions

Chang,

Wu,

Goda

2023

Earthq Engng Struct Dyn

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Proper parameterization of near‐fault ground motions is of critical importance in earthquake engineering, and this process is traditionally performed by directly fitting an analytical pulse model to the original motion. Yet such a process is usually limited by the trial‐and‐error procedure, which is strongly dependent on the initial guesses and may converge to local rather than global minimums. In this study, we propose a progressive (step‐by‐step) iterative approach that can achieve a fully automated parameterization of the velocity pulse contained in near‐fault motions. Assuming that a velocity pulse can be characterized by a pulse model with four key parameters, the approach is conducted by iteratively matching the pulse model to the smoothed ground motion, and the parameterized pulse is analytically derived by best fitting to the smoothed motion not only in the time domain but also in the spectral domain. Specifically, the velocity time history of interest is initially smoothed by a moving average filter so that the low‐frequency content can be filtered out of the original motion, from which the pulse amplitude as well as its epoch is accordingly determined. The coherent velocity pulse is then progressively extracted by performing the nonlinear least‐square‐fitting of the pulse model to the filtered low‐frequency content, during which the remaining parameters, that is, the pulse period, the number of cycles and the phase of the pulse, are estimated successively. Finally, the above procedure is applied repeatedly to the original ground motion by changing an empirical factor controlling the extent of smoothing of the motion so that convergence to local minimums that frequently occurs in the trial‐and‐error procedure could be largely avoided, and best match of the spectrum of the extracted pulse to that of the original motion can be acquired. Fitting quality of the velocity pulses is examined by comparing with existing methods. Prospective applications of the proposed procedure include the stochastic simulations of near‐fault ground motions and parametric investigations of the influence of velocity pulses on various engineered structures.

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

Mazza

Labernarda

2022

Structural Contr & Hlth

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Summary Concave surface sliders (CSSs) are considered as an effective solution for retrofitting adjacent buildings irregular in plan that could undergo significant seismic pounding due to torsional displacements. This is because during the sliding phase there is coincidence between the projection of the gravity mass centre of the superstructure and the stiffness centre of the CSSs. However, unexpected torsional pounding, with amplification in a near‐fault site, may be induced by variability of friction force and lateral stiffness of the CSSs, depending on the axial load and friction coefficient changes during an earthquake. In this work, structural pounding between fixed‐base and base‐isolated reinforced concrete (RC) L‐shaped buildings, placed adjacent to form T‐ and C‐shaped plans, is investigated. A simulated design of the original fixed‐base framed structures is preliminarily carried out in accordance to a former Italian code, for a medium‐risk seismic zone and a typical subsoil class. Then, seismic retrofitting with CSSs is carried out, to attain performance levels imposed by the current Italian code in a high‐risk seismic zone and for moderately‐soft subsoil. A computer code for the pounding analysis between fixed‐base and base‐isolated test structures is developed, in order to compare effects of nonlinear models of the CSSs that consider constant and variable axial load combined with friction coefficient at breakaway and stick–slip and as function of the sliding velocity, axial pressure and rising temperature at the sliding interface. Attention is focused on the pulse‐type nature of near‐fault earthquakes generally observed in the velocity time histories but largely overlooked in the acceleration ones. To this end, automated classification algorithms using wavelet analysis are adopted to compile three datasets of seismic input distinguishing between no‐pulse and velocity‐pulse, the latter further categorised into non‐acceleration and acceleration pulses and rotated along the direction most likely to contain strong pulses.

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Automated classification of near‐fault acceleration pulses using wavelet packets

Cited by 30 publications

References 51 publications

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

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

Automated parameterization of velocity pulses in near‐fault ground motions

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

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