scholarly journals NGA-West2 Empirical Fourier and Duration Models to Generate Adjustable Response Spectra

2019 ◽  
Vol 35 (1) ◽  
pp. 61-93 ◽  
Author(s):  
Sanjay Singh Bora ◽  
Fabrice Cotton ◽  
Frank Scherbaum
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Amplitude Spectrum ◽  
Response Spectra ◽  
Duration Model ◽  
Fourier Amplitude ◽  
Crustal Earthquakes ◽  
Active Tectonic ◽  
Random Vibration Theory ◽  
Fourier Amplitude Spectrum

Adjustment of median ground motion prediction equations (GMPEs) from one region to another region is one of the major challenges within the current practice of seismic hazard analysis. In our approach of generating response spectra, we derive two separate empirical models for a) Fourier amplitude spectrum (FAS) and b) duration of ground motion. To calculate response spectra, the two models are combined within the random vibration theory (RVT) framework. The models are calibrated on recordings obtained from shallow crustal earthquakes in active tectonic regions. We use a subset of NGA-West2 database with M3.2–7.9 earthquakes at distances 0–300 km. The NGA-West2 database expanded over a wide magnitude and distance range facilitates a better constraint over derived models. A frequency-dependent duration model is derived to obtain adjustable response spectral ordinates. Excellent comparison of our approach with other NGA-West2 models implies that it can also be used as a stand-alone model.

Update of the Chiou and Youngs NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

2014 ◽  
Vol 30 (3) ◽  
pp. 1117-1153 ◽  
Author(s):  
Brian S.-J. Chiou ◽  
Robert R. Youngs
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Response Spectra ◽  
Rupture Directivity ◽  
Crustal Earthquakes ◽  
Aleatory Variability ◽  
Source Distance ◽  
Active Tectonic ◽  
Peak Ground Motion ◽  
Horizontal Ground Motion

We present an update to our 2008 NGA model for predicting horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The update is based on analysis of the greatly expanded NGA-West2 ground motion database and numerical simulations. The updated model contains minor adjustments to our 2008 functional form related to style of faulting effects, hanging wall effects, scaling with the depth to top of rupture, scaling with sediment thickness, and the inclusion of additional terms for the effects of fault dip and rupture directivity. In addition, we incorporate regional differences in far-source distance attenuation and site effects between California and other active tectonic regions. Compared to our 2008 NGA model, the predicted medians by the updated model are similar for M > 7 and are lower for M < 5. The aleatory variability is larger than that obtained in our 2008 model.

Vertical Ground Motion Model for PGA, PGV, and Linear Response Spectra Using the NGA-West2 Database

2016 ◽  
Vol 32 (2) ◽  
pp. 979-1004 ◽  
Author(s):  
Yousef Bozorgnia ◽  
Kenneth W. Campbell
Keyword(s):  
Ground Motion ◽  
Response Spectra ◽  
Peak Ground Velocity ◽  
Motion Model ◽  
Acceleration Response ◽  
Ground Acceleration ◽  
Ground Motion Model ◽  
Crustal Earthquakes ◽  
Active Tectonic ◽  
Vertical Ground

We summarize the development of the NGA-West2 Bozorgnia-Campbell empirical ground motion model (GMM) for the vertical components of peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped elastic pseudo-absolute acceleration response spectra (PSA) at vertical periods ranging from 0.01 s to 10 s. In the development of the vertical GMM, similar to our 2014 horizontal GMM, we used the extensive PEER NGA-West2 worldwide database. We consider our new vertical GMM to be valid for shallow crustal earthquakes in active tectonic regions for magnitudes ranging from 3.3 to 7.5–8.5, depending on the style of faulting, and for distances as far as 300 km from the fault.

Summary of the BA18 Ground‐Motion Model for Fourier Amplitude Spectra for Crustal Earthquakes in California

2019 ◽  
Vol 109 (5) ◽  
pp. 2088-2105 ◽  
Author(s):  
Jeff Bayless ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Motion Model ◽  
Fourier Amplitude ◽  
Ground Motion Model ◽  
Crustal Earthquakes ◽  
Magnitude Scaling ◽  
Finite Fault

Abstract We present a summary of the Bayless and Abrahamson (2018b) empirical ground‐motion model (GMM) for shallow crustal earthquakes in California based on the Next Generation Attenuation‐West2 database (Ancheta et al., 2014). This model is denoted as BA18. Rather than the traditional response spectrum GMM, BA18 is developed for the smoothed effective amplitude spectrum (EAS), as defined by the Pacific Earthquake Engineering Research Center (Goulet et al., 2018). The EAS is the orientation‐independent horizontal‐component Fourier amplitude spectrum of ground acceleration. The model is developed using a database dominated by California earthquakes but takes advantage of crustal earthquake data worldwide to constrain the magnitude scaling and geometric spreading. The near‐fault saturation is guided by finite‐fault numerical simulations, and nonlinear site amplification is incorporated using a modified version of Hashash et al. (2018). The model is applicable for rupture distances of 0–300 km, M 3.0–8.0, and over the frequency range 0.1–100 Hz. The model is considered applicable for VS30 in the range 180–1500  m/s, although it is not well constrained for VS30 values >1000  m/s. Models for the median and the aleatory variability of the EAS are developed. Regional models for Japan and Taiwan will be developed in a future update of the model. A MATLAB program that implements the EAS GMM is provided in the Ⓔ supplemental content to this article.

An Empirical Method for Estimating Source Vicinity Ground-Motion Levels on Hard Bedrock and Annual Exceedance Probabilities for Inland Crustal Earthquakes with Sources Difficult to Identify in Advance

2021 ◽  
Vol 111 (5) ◽  
pp. 2408-2425 ◽  
Author(s):  
Reiko Tajima ◽  
Hiroto Tanaka ◽  
Changjiang Wu
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Strong Motion ◽  
Specific Area ◽  
Response Spectra ◽  
Empirical Method ◽  
Fault Rupture ◽  
Vertical Array ◽  
Uniform Hazard Spectra ◽  
Crustal Earthquakes

ABSTRACT The locations and scales of the seismic sources of inland crustal earthquakes without surface fault traces (Mw≲6.5 in Japan) are difficult to identify in advance, even by conducting detailed surveys, and in such a case, it seems rational to uniformly evaluate ground-motion levels in the regions with similar seismogenic conditions. For such earthquakes, we first developed a technique to estimate ground-motion levels in a specific area by calculating the response spectra corresponding to nonexceedance probabilities (NEPs) based on probability density functions derived using strong-motion records. These records were used in the analysis after adjustments to the condition of being and on hard bedrock (VS≈2000–3000  m/s) in the source vicinity. Next, we developed an empirical method to estimate the correspondence between the NEP spectrum levels and their annual exceedance probabilities (AEPs) by considering annual occurrence frequencies for the target event group. Moreover, we showed an example that applied our approach to all over Japan, where a large number of downhole records on stiff baserock (VS≈700–3000  m/s) have been obtained by the KiK-net, a dense nationwide network of vertical array stations (pairs of surface and downhole recordings). In the example, we demonstrated that the empirical AEP spectral levels using our method are consistent with AEP response spectra, that is, uniform hazard spectra, derived from the probabilistic seismic hazard analysis using the kinematic fault rupture modeling method in a previous study.

Digitization noise and accelerograph pen offset associated with Japanese accelerograms

1983 ◽  
Vol 73 (4) ◽  
pp. 1187-1196
Author(s):  
C. B. Crouse ◽  
Trevor Matuschka
Keyword(s):  
United States ◽  
Ground Motion ◽  
Amplitude Spectrum ◽  
Simple Algorithm ◽  
Noise Spectrum ◽  
Fourier Amplitude ◽  
Long Period ◽  
Best Estimate ◽  
Direction Of Movement ◽  
Fourier Amplitude Spectrum

abstract Ground-motion accelerograms recorded in Japan between 1956 and 1978 were recently processed. Preprocessing studies of the accelerograms were required that consisted of: (1) evaluation of the long-period digitization noise in the accelerograms, and (2) correction for initial offset of the recording pen in the SMAC accelerograph. Long-period digitization noise present in each accelerogram was identified from the Fourier Amplitude Spectrum of the uncorrected accelerogram. Similar investigations with United States accelerograms recorded on 70-mm film revealed that the noise in both sets of data had similar characteristics. In nearly all cases, the noise spectrum was proportional to the period, which suggested that fatigue and carelessness of the operator during digitization may have been responsible for the observed period dependence. Correction for initial pen offset was necessary for some Japanese accelerograms because the pen arm was not parallel to the direction of movement of the recording paper. To account for pen offset, values of the initial pen rotation were assumed, and the accelerograms were corrected using a simple algorithm. Our best estimate of the true offset was based not only on the offset which best removed the slanted appearance, but also the offset inferred from the original accelerogram.

Damping Scaling Factors for Elastic Response Spectra for Shallow Crustal Earthquakes in Active Tectonic Regions: “Average” Horizontal Component

2014 ◽  
Vol 30 (2) ◽  
pp. 939-963 ◽  
Author(s):  
Sanaz Rezaeian ◽  
Yousef Bozorgnia ◽  
I. M. Idriss ◽  
Norman Abrahamson ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Ground Motion ◽  
Damping Ratio ◽  
Response Spectra ◽  
Elastic Response ◽  
Site Conditions ◽  
Crustal Earthquakes ◽  
Nonstructural Systems ◽  
Elastic Response Spectra ◽  
Active Tectonic ◽  
Functional Forms

Ground motion prediction equations (GMPEs) for elastic response spectra are typically developed at a 5% viscous damping ratio. In reality, however, structural and nonstructural systems can have other damping ratios. This paper develops a new model for a damping scaling factor ( DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE for damping ratios between 0.5% to 30%. The model is developed based on empirical data from worldwide shallow crustal earthquakes in active tectonic regions. Dependencies of the DSF on potential predictor variables, such as the damping ratio, spectral period, ground motion duration, moment magnitude, source-to-site distance, and site conditions, are examined. The strong influence of duration is captured by the inclusion of both magnitude and distance in the DSF model. Site conditions show weak influence on the DSF. The proposed damping scaling model provides functional forms for the median and logarithmic standard deviation of DSF, and is developed for both RotD50 and GMRotI50 horizontal components. A follow-up paper develops a DSF model for vertical ground motion.

Selection of random vibration theory procedures for the NGA-East project and ground-motion modeling

2021 ◽  
Vol 37 (1_suppl) ◽  
pp. 1420-1439
Author(s):  
Albert R Kottke ◽  
Norman A Abrahamson ◽  
David M Boore ◽  
Yousef Bozorgnia ◽  
Christine A Goulet ◽  
...  
Keyword(s):  
Ground Motion ◽  
Time Domain ◽  
Random Vibration ◽  
Amplitude Spectrum ◽  
Motion Modeling ◽  
Peak Response ◽  
Vibration Theory ◽  
Random Vibration Theory ◽  
The Time Domain ◽  
The Impact

Traditional ground-motion models (GMMs) are used to compute pseudo-spectral acceleration (PSA) from future earthquakes and are generally developed by regression of PSA using a physics-based functional form. PSA is a relatively simple metric that correlates well with the response of several engineering systems and is a metric commonly used in engineering evaluations; however, characteristics of the PSA calculation make application of scaling factors dependent on the frequency content of the input motion, complicating the development and adaptability of GMMs. By comparison, Fourier amplitude spectrum (FAS) represents ground-motion amplitudes that are completely independent from the amplitudes at other frequencies, making them an attractive alternative for GMM development. Random vibration theory (RVT) predicts the peak response of motion in the time domain based on the FAS and a duration, and thus can be used to relate FAS to PSA. Using RVT to compute the expected peak response in the time domain for given FAS therefore presents a significant advantage that is gaining traction in the GMM field. This article provides recommended RVT procedures relevant to GMM development, which were developed for the Next Generation Attenuation (NGA)-East project. In addition, an orientation-independent FAS metric—called the effective amplitude spectrum (EAS)—is developed for use in conjunction with RVT to preserve the mean power of the corresponding two horizontal components considered in traditional PSA-based modeling (i.e., RotD50). The EAS uses a standardized smoothing approach to provide a practical representation of the FAS for ground-motion modeling, while minimizing the impact on the four RVT properties ( zeroth moment, [Formula: see text]; bandwidth parameter, [Formula: see text]; frequency of zero crossings, [Formula: see text]; and frequency of extrema, [Formula: see text]). Although the recommendations were originally developed for NGA-East, they and the methodology they are based on can be adapted to become portable to other GMM and engineering problems requiring the computation of PSA from FAS.

An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra

2008 ◽  
Vol 24 (1) ◽  
pp. 173-215 ◽  
Author(s):  
BrianS-J. Chiou ◽  
Robert R. Youngs
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Hanging Wall ◽  
Response Spectra ◽  
Horizontal Component ◽  
Smooth Functions ◽  
Soil Response ◽  
New Model ◽  
Crustal Earthquakes ◽  
Aleatory Variability

We present a model for estimating horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The model provides predictive relationships for the orientation-independent average horizontal component of ground motions. Relationships are provided for peak acceleration, peak velocity, and 5-percent damped pseudo-spectral acceleration for spectral periods of 0.01 to 10 seconds. The model represents an update of the relationships developed by Sadigh et. al. (1997) and incorporates improved magnitude and distance scaling forms as well as hanging-wall effects. Site effects are represented by smooth functions of average shear wave velocity of the upper 30 m ( VS30) and sediment depth. The new model predicts median ground motion that is similar to Sadigh et. al. (1997) at short spectral period, but lower ground motions at longer periods. The new model produces slightly lower ground motions in the distance range of 10 to 50 km and larger ground motions at larger distances. The aleatory variability in ground motion amplitude was found to depend upon earthquake magnitude and on the degree of nonlinear soil response, For large magnitude earthquakes, the aleatory variability is larger than found by Sadigh et. al. (1997).

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