Simulation-based site amplification model for shallow bedrock sites in Korea

2021 ◽  
pp. 875529302098198
Author(s):  
Muhammad Aaqib ◽  
Duhee Park ◽  
Muhammad Bilal Adeel ◽  
Youssef M A Hashash ◽  
Okan Ilhan
Keyword(s):  
Linear Models ◽  
Site Response ◽  
Site Amplification ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Nonlinear Site Response ◽  
Simulation Based ◽  
Linear And Nonlinear ◽  
Input Motion ◽  
Nonlinear Components

A new simulation-based site amplification model for shallow sites with thickness less than 30 m in Korea is developed. The site amplification model consists of linear and nonlinear components that are developed from one-dimensional linear and nonlinear site response analyses. A suite of measured shear wave velocity profiles is used to develop corresponding randomized profiles. A VS30 scaled linear amplification model and a model dependent on both VS30 and site period are developed. The proposed linear models compare well with the amplification equations developed for the western United States (WUS) at short periods but show a distinct curved bump between 0.1 and 0.5 s that corresponds to the range of site natural periods of shallow sites. The response at periods longer than 0.5 s is demonstrated to be lower than those of the WUS models. The functional form widely used in both WUS and central and eastern North America (CENA), for the nonlinear component of the site amplification model, is employed in this study. The slope of the proposed nonlinear component with respect to the input motion intensity is demonstrated to be higher than those of both the WUS and CENA models, particularly for soft sites with VS30 < 300 m/s and at periods shorter than 0.2 s. The nonlinear component deviates from the models for generic sites even at low ground motion intensities. The comparisons highlight the uniqueness of the amplification characteristics of shallow sites that a generic site amplification model is unable to capture.

Earthquake site response estimation: A weak-motion case study

1992 ◽  
Vol 82 (6) ◽  
pp. 2283-2307
Author(s):  
E. H. Field ◽  
K. H. Jacob ◽  
S. E. Hough
Keyword(s):  
Site Response ◽  
Spectral Ratio ◽  
Large Degree ◽  
One Dimensional ◽  
Loma Prieta Earthquake ◽  
Cross Spectrum ◽  
Downward Bias ◽  
Dimensional Models ◽  
The Cross ◽  
Input Motion

Abstract Using weak-motion recordings of aftershocks of the 1989 Loma Prieta earthquake recorded in Oakland, California, near the failed Nimitz Freeway, two methods have been applied to estimate the site response of an alluvium site and three mud-over-alluvium sites. The first estimate is the traditional spectral ratio, and the second utilizes the cross spectrum. Recordings obtained at a nearby bedrock site are used as estimates of the sediment site input motions. While the two site response estimates produce similar peaks and troughs, there is an approximate factor of 2 difference in amplitudes. This discrepancy is evidence that there is a much greater level of noise than would be expected from the pre-event ambient noise. We interpret this as signal-generated noise produced by scattering from heterogeneities, which causes the true sediment site input to differ significantly from the bedrock site recording. Given this level of noise, the cross-spectrum estimate suffers a severe downward bias (by a factor of 2 in this study) and should probably not be used when the input motion is estimated from a bedrock site recording. The spectral-ratio estimates are relatively unbiased, but the level of noise introduces a large degree of uncertainty. Therefore, inferences about site response from individual spectral ratios should probably be avoided. On the other hand, ensemble averages of the estimates significantly reduce the scatter to reveal resonances that agree quite well in frequency and overall shape with those of one-dimensional models whose parameters were determined independently. A discrepancy of higher observed amplitudes than predicted by theory remains unexplained but most likely results from the effects of boundary layer topography, which are not accounted for by the simple one-dimensional models.

Significance of site natural period effects for linear site amplification in central and eastern North America: Empirical and simulation-based models

2020 ◽  
Vol 36 (1) ◽  
pp. 87-110 ◽  
Author(s):  
Youssef M. A. Hashash ◽  
Okan Ilhan ◽  
Behzad Hassani ◽  
Gail M. Atkinson ◽  
Joseph Harmon ◽  
...  
Keyword(s):  
North America ◽  
Site Response ◽  
Reference Conditions ◽  
Site Amplification ◽  
Empirical Models ◽  
Response Analysis ◽  
Eastern North America ◽  
Natural Period ◽  
Motion Models ◽  
Simulation Based

This article evaluates linear simulation-based and empirical site amplification models including site natural period dependency parameters to account for the distinctive amplification behavior near site fundamental frequencies resulting from the sharp impedance contrast between soil and underlying hard bedrock in central and eastern North America (CENA). The simulation-based amplification models are developed using 581,685 frequency-domain linear analyses generated from a parametric study and include VS30-scaling and site natural period ( Tnat) parameters. The empirical models are derived from residuals analyses of ground-motion models for two reference conditions: B/C boundary ( VS30 = 760 m/s) and CENA hard-rock condition ( VS = 3000 m/s). The simulation-based and empirical models are compared for 8 site profiles in CENA to measured horizontal-to-vertical (H/V) component response spectral (RS) ratios, the mean of linear simulations for similar sites, and one-dimensional (1D) linear site response analysis for four of these sites. Comparisons between observed and estimated site amplification behaviors highlight model dependency on Tnat in CENA. Model consistencies and differences related to the distinct linear amplification features near site fundamental frequency are discussed.

Linear and nonlinear components of human electroretinogram

1984 ◽  
Vol 51 (5) ◽  
pp. 952-967 ◽  
Author(s):  
C. L. Baker ◽  
R. F. Hess
Keyword(s):  
Steady State ◽  
Spatial Frequency ◽  
Step Response ◽  
Linear Component ◽  
Fast Wave ◽  
Uniform Field ◽  
Nonlinear Component ◽  
Symmetric Component ◽  
Linear And Nonlinear ◽  
Nonlinear Components

We compared electroretinographic (ERG) responses to uniform-field and a variety of pattern stimuli using both transient and steady-state analyses. Evidence is provided that for all of these stimuli, the peak at high temporal frequencies in the steady-state response corresponds to the fast wave of the transient response and that the peak at low temporal frequencies corresponds to the slow wave of the step response. A variety of contrast-modulated grating stimuli were used to demonstrate that the fast, high-frequency response can be regarded as the sum of two components, an "odd-symmetric" component, which behaves linearly and is independent of spatial frequency, and an "even-symmetric" component, which behaves nonlinearly and has a band-pass spatial-frequency dependence. The prevailing distinction that is made between pattern and uniform-field ERGs is a consequence of the fact that the uniform-field ERG is dominated by the odd-symmetric (linear) component, whereas the so-called pattern (contrast reversal) ERG reveals the even-symmetric (nonlinear) component in isolation. Since a uniform field can also drive the nonlinear component, the present dichotomy ("luminance" versus "pattern") can be better understood in terms of the linear and nonlinear components of the response rather than in terms of the stimuli that produce them.

NGA-West2 Equations for Predicting Vertical-Component PGA, PGV, and 5%-Damped PSA from Shallow Crustal Earthquakes

2016 ◽  
Vol 32 (2) ◽  
pp. 1005-1031 ◽  
Author(s):  
Jonathan P. Stewart ◽  
David M. Boore ◽  
Emel Seyhan ◽  
Gail M. Atkinson
Keyword(s):  
Site Response ◽  
Vertical Component ◽  
Site Amplification ◽  
Intensity Measures ◽  
Global Database ◽  
Crustal Earthquakes ◽  
Anelastic Attenuation ◽  
Nonlinear Site Response ◽  
Active Tectonic ◽  
Geometric Spreading

We present ground motion prediction equations (GMPEs) for computing natural log means and standard deviations of vertical-component intensity measures (IMs) for shallow crustal earthquakes in active tectonic regions. The equations were derived from a global database with M 3.0–7.9 events. The functions are similar to those for our horizontal GMPEs. We derive equations for the primary M- and distance-dependence of peak acceleration, peak velocity, and 5%-damped pseudo-spectral accelerations at oscillator periods between 0.01–10 s. We observe pronounced M-dependent geometric spreading and region-dependent anelastic attenuation for high-frequency IMs. We do not observe significant region-dependence in site amplification. Aleatory uncertainty is found to decrease with increasing magnitude; within-event variability is independent of distance. Compared to our horizontal-component GMPEs, attenuation rates are broadly comparable (somewhat slower geometric spreading, faster apparent anelastic attenuation), VS30-scaling is reduced, nonlinear site response is much weaker, within-event variability is comparable, and between-event variability is greater.

scholarly journals Two dimensional nonlinear site response analyses

1992 ◽  
Vol 25 (3) ◽  
pp. 222-229
Author(s):  
Tam Larkin ◽  
John Marsh
Keyword(s):  
Material Properties ◽  
Site Response ◽  
Two Dimensional ◽  
Ground Response ◽  
One Dimensional ◽  
Nonlinear Site Response ◽  
Seismic Site Response ◽  
Ground Conditions ◽  
Alluvial Material ◽  
Computer Studies

This paper presents the results of computer studies of the seismic site response of two dimensional alluvial valleys with a variety of geometries and material properties. The alluvial material is modelled as a nonlinear hysteretic solid and results are presented to illustrate the effect of material nonlinearity on surface ground response. Comparative studies with one dimensional analyses are presented and conclusions drawn as to ground conditions that are appropriate to one dimensional site analyses.

Relative Differences between Nonlinear and Equivalent-Linear 1-D Site Response Analyses

2016 ◽  
Vol 32 (3) ◽  
pp. 1845-1865 ◽  
Author(s):  
Byungmin Kim ◽  
Youssef M. A. Hashash ◽  
Jonathan P. Stewart ◽  
Ellen M. Rathje ◽  
Joseph A. Harmon ◽  
...  
Keyword(s):  
Peak Velocity ◽  
Site Response ◽  
Practical Significance ◽  
Response Analysis ◽  
Site Conditions ◽  
One Dimensional ◽  
Equivalent Linear ◽  
Stable Continental Regions ◽  
Input Motion ◽  
Relative Differences

This study investigates the conditions for which one-dimensional (1-D) nonlinear (NL) site response analysis results are distinct from equivalent-linear (EL) results and provides guidance for predicting when differences are large enough to be of practical significance. Relative differences in spectral accelerations and Fourier amplitudes computed from NL and EL analyses are assessed for a range of site conditions and for suites of input motions appropriate for active crustal and stable continental regions. Among several considered parameters, EL/NL differences are most clearly dependent on shear strain index ( I γ), defined as the ratio of input motion peak velocity to time-averaged shear-wave velocity in the top 30 m of the soil profile. For small I γ (generally under 0.03%), EL and NL results are practically identical, whereas at larger strains, differences can be significant for frequencies >0.3 Hz. Frequency-dependent I γ values are recommended for conditions above which NL analyses are preferred to EL.

κ0 for soil sites: Observations from KiK-net sites and their use in constraining small-strain damping profiles for site response analysis

2019 ◽  
Vol 36 (1) ◽  
pp. 111-137 ◽  
Author(s):  
Boqin Xu ◽  
Ellen M Rathje ◽  
Youssef Hashash ◽  
Jonathan Stewart ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Site Response ◽  
Strong Motion ◽  
Small Strain ◽  
Site Amplification ◽  
Site Response Analysis ◽  
Response Analysis ◽  
One Dimensional

Small-strain damping profiles developed from geotechnical laboratory testing have been observed to be smaller than the damping inferred from the observed site amplification from downhole array recordings. This study investigates the high-frequency spectral decay parameter ( κ0) of earthquake motions from soil sites and evaluates the use of κ0 to constrain the small-strain damping profile for one-dimensional site response analysis. Using data from 51 sites from the Kiban-Kyoshin strong motion network (KiK-net) array in Japan and six sites from California, a relationship was developed between κ0 at the surface and both the 30-m time-averaged shear wave velocity ( V s30) and the depth to the 2.5 km/s shear wave velocity horizon ( Z2.5). This relationship demonstrates that κ0 increases with decreasing V s30 and increasing Z2.5. An approach is developed that uses this relationship to establish a target κ0 from which to constrain the small-strain damping profile used in one-dimensional site response analysis. This approach to develop κ0-consistent damping profiles for site response analysis is demonstrated through a recent site amplification study of Central and Eastern North America for the NGA-East project.

Analysis of Site Response and Building Damage Distribution Induced by the 31 October 2002 Earthquake at San Giuliano di Puglia (Italy)

2013 ◽  
Vol 29 (2) ◽  
pp. 497-526 ◽  
Author(s):  
Rodolfo Puglia ◽  
Marco Vona ◽  
Peter Klin ◽  
Chiara Ladina ◽  
Angelo Masi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Site Response ◽  
Spectral Element ◽  
Site Amplification ◽  
Damage Distribution ◽  
Numerical Predictions ◽  
Definition Of ◽  
Subsoil Model ◽  
Molise Earthquake ◽  
Input Motion

This paper concerns the analysis of the site amplification that significantly influenced the non-uniform damage distribution observed at San Giuliano di Puglia (Italy) after the 2002 Molise earthquake (MW = 5.7). In fact, the historical core of the town, settled on outcropping rock, received less damage than the more recent buildings, founded on a clayey subsoil. Comprehensive geotechnical and geophysical investigations allowed a detailed definition of the subsoil model. The seismic response of the subsoil was analyzed through 2-D finite-element and 3-D spectral-element methods. The accuracy of such models was verified by comparing the numerical predictions to the aftershocks recorded by a temporary seismic network. After calibration, the seismic response to a synthetic input motion reproducing the main shock was simulated. The influence of site amplification on the damage distribution observed was finally interpreted by combining the predicted variation of ground motion parameters with the structural vulnerability of the buildings.

A comparative study on linear and nonlinear site response analysis

2006 ◽  
Vol 50 (8) ◽  
pp. 1193-1200 ◽  
Author(s):  
Haydar Arslan ◽  
Bilge Siyahi
Keyword(s):  
Comparative Study ◽  
Site Response ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Nonlinear Site Response ◽  
Linear And Nonlinear

Equivalent linear and nonlinear site response analysis for design and risk assessment of safety-related nuclear structures

2014 ◽  
Vol 275 ◽  
pp. 107-121 ◽  
Author(s):  
Chandrakanth Bolisetti ◽  
Andrew S. Whittaker ◽  
H. Benjamin Mason ◽  
Ibrahim Almufti ◽  
Michael Willford
Keyword(s):  
Risk Assessment ◽  
Site Response ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Nonlinear Site Response ◽  
Equivalent Linear ◽  
Linear And Nonlinear ◽  
Nuclear Structures
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