Free field ground motions at various depths derived from actual seismograph records by using elastodynamic infinite elements

2010 ◽  
Vol 37 (5) ◽  
pp. 689-700 ◽  
Author(s):  
Sakda Katawaethwarag ◽  
Pisidhi Karasudhi
Keyword(s):  
Ground Motions ◽  
Free Field ◽  
Infinite Elements

Conditioned Simulation of Ground-Motion Time Series at Uninstrumented Sites Using Gaussian Process Regression

2021 ◽  
Author(s):  
Aidin Tamhidi ◽  
Nicolas Kuehn ◽  
S. Farid Ghahari ◽  
Arthur J. Rodgers ◽  
Monica D. Kohler ◽  
...  
Keyword(s):  
Time Series ◽  
Gaussian Process ◽  
Ground Motion ◽  
San Francisco ◽  
Earthquake Engineering ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Free Field ◽  
Gaussian Process Regression ◽  
Motion Time

ABSTRACT Ground-motion time series are essential input data in seismic analysis and performance assessment of the built environment. Because instruments to record free-field ground motions are generally sparse, methods are needed to estimate motions at locations with no available ground-motion recording instrumentation. In this study, given a set of observed motions, ground-motion time series at target sites are constructed using a Gaussian process regression (GPR) approach, which treats the real and imaginary parts of the Fourier spectrum as random Gaussian variables. Model training, verification, and applicability studies are carried out using the physics-based simulated ground motions of the 1906 Mw 7.9 San Francisco earthquake and Mw 7.0 Hayward fault scenario earthquake in northern California. The method’s performance is further evaluated using the 2019 Mw 7.1 Ridgecrest earthquake ground motions recorded by the Community Seismic Network stations located in southern California. These evaluations indicate that the trained GPR model is able to adequately estimate the ground-motion time series for frequency ranges that are pertinent for most earthquake engineering applications. The trained GPR model exhibits proper performance in predicting the long-period content of the ground motions as well as directivity pulses.

Soil-structure interaction at CDMG and USGS accelerograph stations

1989 ◽  
Vol 79 (1) ◽  
pp. 1-14
Author(s):  
C. B. Crouse ◽  
Behnam Hushmand
Keyword(s):  
Soil Structure ◽  
Transfer Functions ◽  
Ground Motions ◽  
Free Field ◽  
Soil Structure Interaction ◽  
Imperial Valley ◽  
Structure Interaction ◽  
Fundamental Frequencies ◽  
Vibration Tests ◽  
40 Hz

Abstract Forced harmonic and impulse-response vibration tests were conducted at several California accelerograph stations operated by the California Division of Mines and Geology (CDMG) and U.S. Geological Survey (USGS) to determine the extent to which soil-structure interaction may be affecting the recorded ground motions. The results of the tests on the foundations comprising USGS Station 6 in the Imperial Valley and CDMG Cholame 1E and Fault Zone 3 stations in the Cholame Valley indicated the presence of highly damped fundamental frequencies between 20 and 40 Hz. However, at the much larger Differential Array station, a masonry-block structure approximately 6 km southwest of Station 6, a moderately damped fundamental frequency of 12 Hz was observed. Approximate transfer functions between earthquake motions recorded at the stations and the free-field motions were computed from the response data obtained from the forced harmonic vibration tests. For the three smaller stations, these functions showed peak amplification factors ranging from 1.25 to 1.4 at frequencies between 20 and 40 Hz. The amplification at smaller frequencies was insignificant. For the Differential Array station, the amplification factor was 1.5 at 12 Hz and was roughly 0.6 for frequencies between 14 and 25 Hz. These results suggest that soil-structure interaction will have little effect on ground motions recorded at the smaller stations provided that most of the energy in these motions is confined to frequencies less than approximately 20 Hz. However, at the Differential Array station, soil-structure interaction probably has had, and will continue to have, a significant influence on the motions recorded at this station.

Empirical Site Amplification Modelling for Horizontal and Vertical Ground Motions in Taiwan

2020 ◽  
Author(s):  
Chun-Hsiang Kuo ◽  
Shu-Hsien Chao ◽  
Che-Min Lin ◽  
Jyun-Yan Huang ◽  
Kuo-Liang Wen
Keyword(s):  
Ground Motion ◽  
Amplification Factor ◽  
Ground Motions ◽  
Free Field ◽  
Site Amplification ◽  
Amplification Factors ◽  
Taipei Basin ◽  
Vertical Ground Motions ◽  
Vertical Ground ◽  
Site Amplification Factor

<p>Site amplification behavior are important in ground motion prediction. Seismic waves were amplified and caused significant building damages in the Taipei Basin by the 1986 Hualien offshore (subduction interface) and the 1999 Chi-Chi earthquakes (crustal), for which both of the epicentral distances were nearly 100 km. To understand local site amplifications in Taiwan, empirical site amplification factors for both horizontal and vertical ground motions are studied using recently constructed strong motion and site databases for the free-field TSMIP stations. Records of large magnitude earthquakes of M<sub>W</sub> larger than 5.5 from 1991 to 2016 were selected for this study. Site amplification factors at site conditions with Vs30 between 120 m/s to 1600 m/s and bedrock accelerations up to 0.8 g were evaluated using ratios of spectral accelerations at different periods. The reference site condition, i.e. the engineering bedrock, is assumed as Vs30 of 760 m/s (B/C boundary) in this study. Our empirical site amplification form are borrowed from the site response function of ASK14 and CY14 ground motion models in NGA-West2 project with slight modification. Therefore our site amplification model includes a linear amplification term and a nonlinear deamplification term. The coefficients of the empirical models were obtained by a nonlinear regression analysis using the selected Taiwan data. Site amplification factor is a function of Vs30 and spectral intensity in the model. Similar linear site amplification factor to the NGA models is derived in our model; however, more significant soil nonlinearity behavior than the NGA models is likely captured from the empirical data. The amplification factor in vertical component is smaller than that in horizontal.</p>

Effects of SSI on EPR™ In-Structure Response for a Rock Site: Coherent and Incoherent High Frequency Ground Motion

2010 ◽  
Author(s):  
James J. Johnson ◽  
Oliver Schneider ◽  
Werner Schuetz ◽  
Philippe Monette ◽  
Alejandro P. Asfura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Free Field ◽  
Response Spectra ◽  
Frequency Content ◽  
Structure Response ◽  
Standard Design ◽  
Rock Site ◽  
High Frequency Content

Recently, probabilistic seismic hazard assessments (PSHAs) performed for hard sites world-wide have yielded uniform hazard response spectra (UHRS) with significant high frequency content, i.e., frequency content greater than 10 Hz. This high frequency content is frequently due to near-field relatively low magnitude events. It is well known that these high frequency ground motions are not damaging to ductile structures, systems, and components (SSCs). One method of addressing the effect of these high frequency ground motions on structure response is to take into account the incoherency of ground motion. Over the past 25 years, free-field ground motion has been recorded providing an adequate basis for the development of ground motion coherency functions necessary to assess the effect of incoherence on nuclear power plant structures. The subject of this study was the AREVA NP EPR™ (European Power Reactor) nuclear island (NI) standard design. The effect of incoherency of ground motion on in-structure response spectra (ISRS) was assessed for the NI founded on a stiff rock site and subjected to high frequency enhanced input for hard rock sites. The ISRS at numerous locations and directions in the structures were calculated and compared. SSI is shown to be an important phenomenon for structures founded on stiff sites and subjected to high frequency ground motions.

Free-Field Particle Velocity Recordings of the January 31, 1986 Northeastern Ohio Earthquake

1987 ◽  
Vol 58 (4) ◽  
pp. 111-117
Author(s):  
R. Street ◽  
A. Zekulin ◽  
M. Mann
Keyword(s):  
Ground Motion ◽  
Particle Velocity ◽  
Ground Motions ◽  
Free Field ◽  
Motion Model ◽  
Ground Motion Model ◽  
Western Pennsylvania ◽  
Coal Fields

Abstract The January 31, 1986 earthquake in northeastern Ohio triggered eight biast monitors in the coal fields of southeastern Ohio and one in western Pennsylvania at epicentral distances of 128 to 297 kilometers from the earthquake. Recordings of the free-field ground motions exhibit predominant frequencies of 1 to 10 Hz, and are consistent with the ground motion model proposed by Nuttli and Herrmann (1984) for the propagation of Lg waves.

scholarly journals Empirical Spectral Amplification Function for a Reference Site Near Keddara Dam in Algeria using Strong Motion Data.

2021 ◽  
Author(s):  
Faouzi Gherboudj ◽  
Toufiq Ouzandja ◽  
Rabah Bensalem
Keyword(s):  
Ground Motion ◽  
Reference Site ◽  
Ground Motions ◽  
Free Field ◽  
Strong Motion ◽  
Ambient Vibration ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Strong Motion Data ◽  
Motion Data

Abstract This paper deals with empirical spectral amplification function for a reference site (STK) near Keddara dam in Algeria using local strong ground motion of earthquakes of magnitudes Mw 4.0-6.8. Amplification function is obtained as the 5% damped mean spectral ratio of surface observed and the rock predicted ground motions and it is compared to the ambient vibration HVSR which shows a good agreement in terms of fundamental frequency and curve tendency. In addition, recorded ground motions are compared to surface predicted motion with modified GMPE, the site term of the local ground motion prediction equation is adjusted based on the obtained amplification function of the free field STK site. Examples of the M 6.8, M5.4 and M4.7 earthquakes show clearly the advantage of using the adjusted Ground Motion Prediction Equations (GMPE) for predicting surface ground motion. Site effect characterization and the adjusted GMPE presented in this study provide the basis elements toward partially non ergodic site specific-Probabilistic seismic hazard assessment (PSHA) application based on local strong motion data in Algeria.

scholarly journals Free Field Surface Motion at Different Site Types due to Near-Fault Ground Motions

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Jagabandhu Dixit ◽  
D. M. Dewaikar ◽  
R. S. Jangid
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Free Field ◽  
Response Spectra ◽  
Response Analysis ◽  
Acceleration Response ◽  
Surface Motion ◽  
Near Fault ◽  
Acceleration Response Spectra ◽  
Site Category

Seismic hazards during many disastrous earthquakes are observed to be aggravating at the sites with the soft soil deposits due to amplification of ground motion. The characteristics of strong ground motion, the site category, depth of the soil column, type of rock strata, and the dynamic soil properties at a particular site significantly influence the free field motion during an earthquake. In this paper, free field surface motion is evaluated via seismic site response analysis that involves the propagation of earthquake ground motions from the bedrock through the overlying soil layers to the ground surface. These analyses are carried out for multiple near-fault seismic ground motions at 142 locations in Mumbai city categorized into different site classes. The free field surface motion is quantified in terms of amplification ratio, spectral relative velocity, and spectral acceleration. Seismic site coefficients at different time periods are also evaluated for each site category due to near-fault ground motions from the acceleration response spectra of free field surface motion at each site and the corresponding acceleration response spectra at a reference rock outcrop site.

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