Application of wavelet for seismic wave analysis in Kathmandu Valley after the 2015 Gorkha earthquake, Nepal

AbstractIn this paper, we estimate the seismogenic energy during the Nepal Earthquake (25 April 2015) and studied the ground motion time-frequency characteristics in Kathmandu valley. The idea to analyze time-frequency characteristic of seismogenic energy signal is based on wavelet transform which we employed here. Wavelet transform has been used as a powerful signal analysis tools in various fields like compression, time-frequency analysis, earthquake parameter determination, climate studies, etc. This technique is particularly suitable for non-stationary signal. It is well recognized that the earthquake ground motion is a non-stationary random process. In order to characterize a non-stationary random process, it is required immeasurable samples in the mathematical sense. The wavelet transformation procedures that we follow here helps in random analyses of linear and non-linear structural systems, which are subjected to earthquake ground motion. The manners of seismic ground motion are characterized through wavelet coefficients associated to these signals. Both continuous wavelet transform (CWT) and discrete wavelet transform (DWT) techniques are applied to study ground motion in Kathmandu Valley in horizontal and vertical directions. These techniques help to point out the long-period ground motion with site response. We found that the long-period ground motions have enough power for structural damage. Comparing both the horizontal and the vertical motion, we observed that the most of the high amplitude signals are associated with the vertical motion: the high energy is released in that direction. It is found that the seismic energy is damped soon after the main event; however the period of damping is different. This can be seen on DWT curve where square wavelet coefficient is high at the time of aftershock and the value decrease with time. In other words, it is mostly associated with the arrival of Rayleigh waves. We concluded that long-period ground motions should be studied by earthquake engineers in order to avoid structural damage during the earthquake. Hence, by using wavelet technique we can specify the vulnerability of seismically active region and local topological features out there.

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A Study of Elasto-Plastic Response of Single Degree of Freedom System Using Artificial Ground Motions With Given Time-Frequency Characteristics

ASME 2010 Pressure Vessels and Piping Conference: Volume 8 ◽

10.1115/pvp2010-25381 ◽

2010 ◽

Cited By ~ 1

Author(s):

Ichiro Ichihashi ◽

Akira Sone ◽

Arata Masuda ◽

Daisuke Iba

Keyword(s):

Ground Motion ◽

Response Spectrum ◽

Ground Motions ◽

Frequency Characteristics ◽

Earthquake Ground Motion ◽

Time Frequency ◽

Displacement Response ◽

Earthquake Ground Motions ◽

Design Response Spectrum ◽

The Given

In this paper, a number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motion as well as the given target response spectrum are generated using wavelet transform. The maximum non-dimensional displacement of elasto-plastic structures excited these artificial earthquake ground motions are calculated numerically. Displacement response, velocity response and cumulative input energy are shown in the case of the ground motion which cause larger displacement response. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes lager maximum displacement response of elasto-plastic structure are suggested.

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An Ensemble of Ground Motions Simulation Based on Discrete Stationary Wavelet Transform

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.166-169.2408 ◽

2012 ◽

Vol 166-169 ◽

pp. 2408-2411

Author(s):

Quan Bai ◽

Liang Hua Fu ◽

Wen Bo Bao ◽

Sheng Ji Jin ◽

Da Sheng Zhang

Keyword(s):

Wavelet Transform ◽

Discrete Wavelet Transform ◽

Ground Motion ◽

Ground Motions ◽

Earthquake Ground Motion ◽

Response Analysis ◽

Discrete Wavelet ◽

Superposition Method ◽

Stationary Characteristic ◽

Simulation Based

Simulation of earthquake ground motion was a hot topic for structure seismic response analysis. According to the problems in simulating ground motion history with harmony superposition method, such as more interference of human factors and simulated ground motion history didn’t have frequency non-stationary characteristic, a novel method of ground motion simulation based on stationary discrete wavelet transform was presented. Using stationary discrete wavelet transform, the parent ground motion history was decomposed into different frequency bands, and the coefficients were modified. Using inverse stationary discrete wavelet transform, an ensemble of ground motions were simulated whose statistics closely resemble those of the parent history. Through a numerical example, the statistic characteristics of simulated histories were compared with the original values, and the feasibility and correctness of presented method was illustrated.

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Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

Bulletin of Earthquake Engineering ◽

10.1007/s10518-021-01077-1 ◽

2021 ◽

Author(s):

Fabio Sabetta ◽

Antonio Pugliese ◽

Gabriele Fiorentino ◽

Giovanni Lanzano ◽

Lucia Luzi

Keyword(s):

Ground Motion ◽

Ground Motions ◽

Strong Motion ◽

Stochastic Simulations ◽

Model Parameters ◽

Motion Model ◽

Arias Intensity ◽

Time Frequency ◽

Ground Motion Model ◽

Ground Motion Records

AbstractThis work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

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Building Seismic Vulnerability Study for China High Rises

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.2301 ◽

2013 ◽

Vol 353-356 ◽

pp. 2301-2304

Author(s):

Fan Wu ◽

Ming Wang ◽

Xin Yuan Yang

Keyword(s):

Ground Motion ◽

Structural Damage ◽

Seismic Vulnerability ◽

Fragility Curves ◽

Response Spectrum ◽

Earthquake Ground Motion ◽

Published Data ◽

Rapid Urbanization ◽

High Rise ◽

Story Drift

High-rise buildings, as a result of rapid urbanization in China, become one of popular structure kind. However, there have been few seismic vulnerability studies on high-rise buildings, and few fragility curves have been developed for the buildings. Based on the published data of more than 50 high rises and super high rises, the structural information such as building heights, mode periods, locations and sites, the maximum design story drift ratios, are collected and analyzed. The vulnerability analysis for high rises uses response spectrum displacement as seismic ground motion input, since the structures have comparatively long natural period. Using statistics and regression analysis, the relationship between the maximum story drift ratio and response spectrum displacement is established. Based on height groups and earthquake design codes, the fragility curves of different performance levels can be developed. These curves can provide good loss estimation of high rise structural damage under earthquake ground motion.

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The 30 October 2020 Samos (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions

10.21203/rs.3.rs-215817/v1 ◽

2021 ◽

Author(s):

Aybige Akinci ◽

Daniele Cheloni ◽

AHMET ANIL DINDAR

Keyword(s):

Ground Motion ◽

Structural Damage ◽

Ground Motions ◽

Aegean Sea ◽

Peak Ground Velocity ◽

Ground Shaking ◽

Local Site ◽

Eastern Aegean ◽

Motion Characteristics ◽

Eastern Aegean Sea

Abstract On 30 October 2020 a MW 7.0 earthquake occurred in the eastern Aegean Sea, between the Greek island of Samos and Turkey’s Aegean coast, causing considerable seismic damage and deaths, especially in the Turkish city of Izmir, approximately 70 km from the epicenter. In this study, we provide a detailed description of the Samos earthquake, starting from the fault rupture to the ground motion characteristics. We first use Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data to constrain the source mechanisms. Then, we utilize this information to analyze the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and spectral pseudo-accelerations. Modelling of geodetic data shows that the Samos earthquake ruptured a NNE-dipping normal fault located offshore north of Samos, with up to 2.5-3 m of slip and an estimated geodetic moment of 3.3 ⨯ 1019 Nm (MW 7.0). Although low PGA were induced by the earthquake, the ground shaking was strongly amplified in Izmir throughout the alluvial sediments. Structural damage observed in Izmir reveals the potential of seismic risk due to the local site effects. To better understand the earthquake characteristics, we generated and compared stochastic strong ground motions with the observed ground motion parameters as well as the ground motion prediction equations (GMPEs), exploring also the efficacy of the region-specific parameters which may be improved to better predict the expected ground shaking from future large earthquakes in the region.

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Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations

Bulletin of the Seismological Society of America ◽

10.1785/0120210101 ◽

2021 ◽

Author(s):

Alan Poulos ◽

Eduardo Miranda ◽

Jack W. Baker

Keyword(s):

Stochastic Process ◽

Ground Motion ◽

Ground Motions ◽

Gaussian White Noise ◽

Response Spectra ◽

Orientation Dependence ◽

Stochastic Simulations ◽

Earthquake Ground Motion ◽

Significant Duration ◽

Simulated Ground Motions

ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.

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A Study on Maximum Responses and Their Variances of Elasto-Plastic Structures Subjected to Synthesized Ground Motions

Volume 8: Seismic Engineering ◽

10.1115/pvp2014-28133 ◽

2014 ◽

Author(s):

Akira Sone ◽

Ichiro Ichihashi ◽

Arata Masuda

Keyword(s):

Wavelet Transform ◽

Coefficient Of Variation ◽

Response Spectrum ◽

Ground Motions ◽

Frequency Characteristics ◽

Target Response ◽

Maximum Displacement ◽

Time Frequency ◽

Earthquake Ground Motions ◽

The Given

A number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motions as well as the given target response spectrum are generated using wavelet transform. The coefficient of variation (C.O.V..) of maximum displacement on elasto-plastic SDOF systems excited by these artificial ground motions are numerically evaluated.

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SEISMIC COLLAPSING ANALYSIS OF ONE-STORY WOODEN KINDERGARTEN STRUCTURE AGAINST STRONG EARTHQUAKE GROUND MOTION

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2015.96 ◽

2015 ◽

Vol 2 (1) ◽

Author(s):

Tomiya Takatani ◽

Hayato Nishikawa

Keyword(s):

Ground Motion ◽

Strong Earthquake ◽

Process Analysis ◽

Ground Motions ◽

Seismic Intensity ◽

Earthquake Ground Motion ◽

Intensity Level ◽

Wooden Structure ◽

Old Japanese ◽

Upper Level

3-D collapsing process analysis of an old Japanese-style one-story wooden structure under two strong earthquake ground motions with a seismic intensity level was car-ried out in order to investigate the seismic performance of this one-story wooden structure without/with seismic retrofit. As a result, this wooden structure collapsed against a strong earthquake ground motion with the JMA seismic intensity “6 upper” level.

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