scholarly journals Numerical Analysis of Seismic Site Effects in Loess Region of Western China under Strong Earthquake Excitations

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Tuo Chen ◽  
Zhijian Wu ◽  
Yanhu Mu ◽  
Ping Wang ◽  
Qiyin Zhu
Keyword(s):  
Numerical Analysis ◽  
Ground Motion ◽  
Site Effects ◽  
Seismic Damage ◽  
Gansu Province ◽  
Seismic Excitation ◽  
Western China ◽  
Response Analysis ◽  
Mountainous Area ◽  
Seismic Site Effects

The Loess Plateau is one of the most tectonically and seismically active areas in the world. Observations from past strong earthquakes, particularly the Minxian–Zhangxian and Wenchuan earthquakes, have shown distinctive evidence of seismic site effects in the mountainous area of southeastern Gansu province. In this study, seismic damage in the loess areas of southeastern Gansu province induced by these earthquakes was investigated and briefly described. Different types of ground motion were selected, and the one-dimensional equivalent linear method was used for numerical analysis of the ground motion effects in the loess regions. Moreover, seismic response analysis of a typical loess tableland was conducted. The results showed that the seismic responses of a typical loess tableland under different seismic excitations have totally different dynamic characteristics. Moreover, the seismic damage in loess regions was more serious under far-field seismic excitation compared with near-field seismic excitation with the same peak acceleration. Through this study, the quantitative assessment of ground motion effects can be approximately estimated and the mechanism of site amplification effects on ground motion is further explained.

The Effect of Site Condition on Ground Motion in Gansu Province during the Wenchun Ms8.0 Earthquake

2012 ◽  
Vol 594-597 ◽  
pp. 1658-1667
Author(s):  
Zhi Jian Wu ◽  
Lan Min Wang ◽  
Ping Wang ◽  
Hang Shi ◽  
Tuo Chen
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Design ◽  
Site Effects ◽  
Strong Motion ◽  
Gansu Province ◽  
Response Analysis ◽  
Site Condition ◽  
Seismic Response Analysis ◽  
Ground Acceleration

Based on mobile strong motion array observation, borehole exploration and site seismic response analysis, the site effects of mountainous topography in southeastern Gansu and the topography of loess tableland on ground motion were investigated in details. The analysis on acceleration records of aftershocks showed that the peak ground acceleration at top of the mountain is nearly 2 times of that at the foot of it. The seismic response analysis of sites shows that the loess tableland may amplify PGA by 1.44-2.0 times. Therefore, site effects of mountains and loess topography on ground motion should been taken account into seismic design.

Modeling nonlinear site effects in physics-based ground motion simulations of the 2010–2011 Canterbury earthquake sequence

2020 ◽  
Vol 36 (2) ◽  
pp. 856-879 ◽  
Author(s):  
Christopher A de la Torre ◽  
Brendon A Bradley ◽  
Robin L Lee
Keyword(s):  
Wave Propagation ◽  
Ground Motion ◽  
Site Effects ◽  
Ground Motions ◽  
Site Amplification ◽  
Earthquake Sequence ◽  
Response Analysis ◽  
Site Specific ◽  
Ground Motion Simulations ◽  
Empirical Ground

This study examines the performance of nonlinear total stress one-dimensional (1D) wave propagation site response analysis for modeling site effects in physics-based ground motion simulations of the 2010–2011 Canterbury, New Zealand earthquake sequence. This approach explicitly models three-dimensional (3D) ground motion phenomena at the regional scale, and detailed site effects at the local scale. The approach is compared with a more commonly used empirical VS30-based method of computing site amplification for simulated ground motions, as well as prediction via an empirical ground motion model. Site-specific ground response analysis is performed at 20 strong motion stations in Christchurch for 11 earthquakes with 4.7≤ MW≤7.1. When compared with the VS30-based approach, the wave propagation analysis reduces both overall model bias and uncertainty in site-to-site residuals at the fundamental period, and significantly reduces systematic residuals for soft or “atypical” sites that exhibit strong site amplification. The comparable performance in ground motion prediction between the physics-based simulation method and empirical ground motion models suggests the former is a viable approach for generating site-specific ground motions for geotechnical and structural response history analyses.

scholarly journals Seismic response analysis for Romanian extra-carpathian sedimentary areas

2021 ◽  
pp. 83-92
Author(s):  
Gheorghe Marmureanu ◽  
Carmen Ortanza Cioflan ◽  
Bogdan Felix Apostol
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Site Effects ◽  
Spectral Characteristics ◽  
Response Analysis ◽  
Seismic Events ◽  
Seismic Response Analysis ◽  
Local Conditions ◽  
Sedimentary Deposits ◽  
New Perspective

The seismic response of the ground motion is analysed using processed recordings and related spectral characteristics. The analysis is carried out for few representative different sites, with different geological local conditions. Data used are recordings from the last strongest seismic events (1986, August 30, Mw = 7.1, 1990, May 30, Mw = 6.9 and 1990, May 31, Mw=6.4). The approach used herein to assess the particular features of the seismic effects could open a new perspective in microzoning and risk studies. In the context of Vrancea-intermediate depth seismicity, whose effects are encountered at long epicentral distances, the choice of these sites is fully justified. Therefore the paper intends to focus on the particularities in the site effects that occur due to the sedimentary deposits’ oscillation under strong seismic ground motion for different areas. The spectral amplification factors are introduced in order to have a quantitative representation with respect to the variability of site effects.

scholarly journals Numerical Analysis of Ground Motion Effects in the Loess Regions of Western China

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Tuo Chen ◽  
Wei Ma ◽  
Jianzhou Wang
Keyword(s):  
Numerical Analysis ◽  
Ground Motion ◽  
Soil Structure ◽  
Seismic Vulnerability ◽  
Field Investigation ◽  
Western China ◽  
Triaxial Tests ◽  
High Porosity ◽  
Special Soil

Loess is widely distributed in the western part of China and its area comprises 6.6% of Chinese territory. Because of the characteristics of high porosity, low strength, and weak cementation, the loess is characterized by high seismic vulnerability which has been observed and confirmed by many researchers at home and abroad. The postquake field investigation and the laboratory study have shown that the ground motion effects, including the amplification effects and slope effects, were obvious in loess sites. Moreover, the causes of landslides, seismic subsidence, and liquefaction were mainly attributed to this special soil structure and properties. In this paper, based on the data of shear wave velocity of typical loess in Lanzhou region, combining the results of dynamic triaxial tests, the numerical analysis of ground motion effects in the loess regions is analyzed. The results reveal how the ground motion effects are checked and demonstrated the important role of numerical simulations while studying the characteristics of ground motions.

scholarly journals Does the One-Dimensional Assumption Hold for Site Response Analysis? A Study of Seismic Site Responses and Implication for Ground Motion Assessment Using KiK-Net Strong-Motion Data

2019 ◽  
Vol 35 (2) ◽  
pp. 883-905 ◽  
Author(s):  
Marco Pilz ◽  
Fabrice Cotton
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Site Response ◽  
Three Dimensional ◽  
Strong Motion ◽  
Site Response Analysis ◽  
Response Analysis ◽  
One Dimensional ◽  
Ground Motion Variability ◽  
The One

The one-dimensional (1-D) approach is still the dominant method to incorporate site effects in engineering applications. To bridge the 1-D to multidimensional site response analysis, we develop quantitative criteria and a reproducible method to identify KiK-net sites with significant deviations from 1-D behavior. We found that 158 out of 354 show two-dimensional (2-D) and three-dimensional (3-D) effects, extending the resonance toward shorter periods at which 2-D or 3-D site effects exceed those of the classic 1-D configurations and imposing an additional amplification to that caused by the impedance contrast alone. Such 2-D and 3-D effects go along with a large within-station ground motion variability. Remarkably, these effects are found to be more pronounced for small impedance contrasts. While it is hardly possible to identify common features in ground motion behavior for stations with similar topography typologies, it is not over-conservative to apply a safety factor to account for 2-D and 3-D site effects in ground motion modeling.

The Random Response Analysis of Structure Subjected to Non-Stationary Seismic Excitation

2012 ◽  
Vol 446-449 ◽  
pp. 3287-3290
Author(s):  
Hao Wu ◽  
Xun An Zhang
Keyword(s):  
Ground Motion ◽  
Random Excitation ◽  
Seismic Excitation ◽  
Earthquake Ground Motion ◽  
Response Analysis ◽  
Rock Surface ◽  
Random Response ◽  
Spectrum Prediction ◽  
Hilbert Huang Transform ◽  
Evolutionary Spectrum

The evolutionary power spectrum which can reflect the non-stationary characteristics of earthquake ground motion is estimated by the Hilbert-Huang Transform (HHT), and with reference to the experiential statistical method, an evolutionary spectrum prediction model for given earthquake magnitude and distance is established based on the 121 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U S. The pseudo excitation method is adopted to acquire the solution for structure random response under specific non-stationary seismic excitation. The results demonstrate that the non-stationary contents included in seismic excitation will enlarge greatly the random response of structure in comparison with uniform modulation random excitation.

National Mitigation Strategy against Earthquakes in Central Asia

2020 ◽  
Author(s):  
Sung-Woo Moon ◽  
Farkhod Hakimov ◽  
Jong Kim ◽  
Klaus Reicherter ◽  
Hans-Balder Havenith ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Central Asia ◽  
Ground Motion ◽  
Urban Areas ◽  
Site Effects ◽  
Site Response ◽  
Engineering Properties ◽  
Response Analysis ◽  
Earthquake Scenarios ◽  
Geological Conditions

<p>Throughout history, earthquakes have caused extensive damages in urban areas with important infrastructures and high population density. Especially, earthquakes have extensively damaged many regions of Central Asia (e.g., Tashkent in 1966, and Almaty in 1911). Hence, the estimation of the seismic hazard of the urban areas in Central Asia is very important due to the high level of seismicity in Central Asia and the rapid construction of new buildings. The high earthquake-induced damages in the cities often result from the local geological conditions and engineering properties of the soils that can produce significant site effects. Such seismic effects combined with the high vulnerability of buildings can result in extreme disasters during earthquakes. Therefore, geotechnical engineers/seismologists should decide to divide the city into specific microzones depending on their site effects and soil properties. However, conventional approaches in Central Asia have been proposed, based on (1) general engineering geological information; (2) the building code based on the estimates of the ground motions in terms of MSK-64 scale developed in 1978; and (3) the quantitative assessment only mapping and overlaying the data.</p><p>By characterizing the soft layers of their nature, thickness, and structure, and assessing the numerical model developed for the high-seismicity area of Central Asia, we can better assess specific site effects in each region of Central Asia. In addition, to predict the essential consequences of earthquakes, physically-based ground motion simulations should be developed by numerical simulations considering all possible processes of seismic wave propagation. Compared to empirical ground-motion predictions, numerical simulations of earthquake scenarios will provide much more flexible and better-suited solutions for most applications – especially those involving complex city environments. The ground-motion prediction equations or stochastic ground-motion estimates integrate characteristics of the earthquake source, path, attenuation, and site effects via approximate or statistical approaches. This method will provide rapid solutions that may be valid for a well-known context and would also be applied in Central Asia, for comparison with the numerical simulations. Finally, the quantitative approach for microzoning map incorporated with numerical simulation/site response analysis, for infrastructures (e.g., buildings, bridges, and dams) will be significantly useful in the future.</p>

scholarly journals Summary of Research on Site Response Analysis

2021 ◽  
Vol 276 ◽  
pp. 02024
Author(s):  
Jing Cai ◽  
Jianqi Lu ◽  
Shanyou Li
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Reference Site ◽  
Site Response ◽  
Response Analysis ◽  
Observation Data ◽  
Empirical Methods ◽  
Theoretical Methods ◽  
Advantages And Disadvantages ◽  
Soil Site

A large number of seismic observation data and macroscopic survey of earthquake damage indicate that soil site may amplify the intensity of ground-motion and thus aggravate the damage to the structures on the soil site[1]. The influence of site response on ground motion is one of the most important topics in earthquake engineering. The methods of predicting the site effects can be divided into two groups with respect to theoretical methods and empirical methods. The theoretical methods of predicting site effects are to analyse the site response to ground motion based on the theory of seismic wave propagation in which the detailed soil information is required. Whereas the empirical methods predicting the site effects by empirical prediction model which is determined using observed seismic data or ground pulsation data. According to whether the reference site is introduced, the empirical methods can be further divided into the reference site method and the non-reference site method. This article introduces in detail the principles, advantages and disadvantages of various methods of analysing site effects, which is of reference value for further research on site ground motion response.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

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