scholarly journals Seismic response analysis of loess site under far-field bedrock ground motion of the Wenchuan earthquake

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254871
Author(s):  
Tuo Chen
Keyword(s):  
Ground Motion ◽  
Seismic Waves ◽  
Linear Method ◽  
Soil Layer ◽  
Resonance Phenomenon ◽  
Amplification Coefficient ◽  
Response Analysis ◽  
Topographic Effects ◽  
Far Field ◽  
Short Period

In this paper, considering the far-field seismic input, an accelerogram recorded in the bedrock at Wuquan Mountain in Lanzhou city during the 2008 Wenchuan Ms8.0 earthquake was selected, and numerical dynamic analyses were conducted. The one-dimensional equivalent linear method was implemented to estimate the ground motion effects in the loess regions. Thereafter, slope topographic effects on ground motion were studied by applying the dynamic finite-element method. The results revealed the relationship between the PGA amplification coefficients and the soil layer thickness, which confirmed that the dynamic response of the sites had obvious nonlinear characteristics. The results also showed that there was an obvious difference in the dynamic magnification factor between the short-period and long-period structures. Moreover, it was found that the amplification coefficient of the observation point at the free surface was greater than the point inside the soil at the same depth, which mainly occurred in the upper slope. Through this study, the quantitative assessment of ground motion effects in loess regions can be approximately estimated, and the amplification mechanism of the far-field ground motion mechanism can be further explained. In addition to the refraction and reflection theory of seismic waves, the resonance phenomenon may help explain the slope topographic effect through spectrum analysis.

Study on Far-Field Ground Motion Characteristics

2013 ◽  
Vol 438-439 ◽  
pp. 1471-1473
Author(s):  
Gong Lian Chen ◽  
Wen Zheng Lu ◽  
Lei Wang ◽  
Qi Wu
Keyword(s):  
Ground Motion ◽  
Seismic Design ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Engineering Application ◽  
Seismic Attenuation ◽  
Far Field ◽  
Propagation Process ◽  
Ground Acceleration ◽  
Motion Characteristics

In order to study the far-field ground motion characteristics and the attenuation of seismic waves, the peak ground acceleration (velocity, displacement), time of duration and response spectrum of the seismic waves were analyzed in this paper. Through the investigation of earthquake wave propagation process, the seismic attenuation low was analyzed. This study can provide technical support for the seismic design of long period structures and related engineering application.

scholarly journals Study on the influence of seafloor soft soil layer on seismic ground motion

2020 ◽  
Author(s):  
Jingyan Lan ◽  
Juan Liu ◽  
Xing Song
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Sea Water ◽  
Response Spectrum ◽  
Soft Soil ◽  
Free Field ◽  
Soil Layer ◽  
Response Analysis ◽  
Peak Acceleration ◽  
Seismic Response Analysis

Abstract. In the complex medium system of sea area, the overlying sea water and the surface soft soil have a significant impact on the seafloor ground motion, which brings great seismic risk to the safety of offshore engineering structures. In this paper, four sets of typical free field models are constructed and established, which are land model, land model with surface soft soil, sea model and sea model with surface soft soil. The dynamic finite difference method is used to carry out two-dimensional seismic response analysis of typical free field based on the input forms about P and SV wave. By comparing the seismic response analysis results of four groups of calculation models, the effects of overlying seawater and soft soil on peak acceleration and acceleration response spectrum are studied. The results show that when SV wave is input, the peak acceleration and response spectrum of the surface of soft soil on the surface and the seabed surface can be amplified, while the overlying sea water can significantly reduce the ground motion. When P wave is used, the effect of overlying seawater and soft soil on peak acceleration and response spectrum of surface and seabed can be ignored. The peak acceleration decreases first and then increases from the bottom to the surface, and the difference of peak acceleration calculated by four free field models is not obvious. The results show that the overlying sea water and the surface soft soil layer have little effect on the peak acceleration of ground motion below the surface.

Simplified Method of Isolated Structure Collapse Capacity Part, (I): Ground Motion Intensity Measure

2013 ◽  
Vol 275-277 ◽  
pp. 1466-1470
Author(s):  
Yang Liu ◽  
Wen Guang Liu ◽  
Wen Fu He ◽  
Qiao Rong Yang
Keyword(s):  
Correlation Coefficient ◽  
Ground Motion ◽  
Ground Motions ◽  
Near Field ◽  
Far Field ◽  
Intensity Measure ◽  
Maximum Deformation ◽  
Average Value ◽  
Short Period ◽  
Ground Motion Intensity Measure

The equivalent velocity spectrum as a new ground motion intensity measure (IM) characterization parameter is proposed in this paper. 44 far field ground motions and 20 near-field high-speed pulse seismic waves were used for single-degree-freedom (SDOF) nonlinear time history analysis, respectively. The correlations between five IMs and maximum deformation for SDOF at various periods and different yield coefficients were analyzed. The results show that for the structures with medium-to-long period, the correlation coefficient average value of the proposed equivalent speed and maximum deformation is more than 0.6, and maximum of those is more than 0.9. The correlation coefficient average value by using the proposed equivalent speed under far field ground motions is more than those under near field ground motions. The P-delta effect on the correlation coefficients between proposed IM for the structures with medium-to-short period is significant

A Far-Field Ground-Motion Model for the North Australian Craton from Plate-Margin Earthquakes

2021 ◽  
Author(s):  
Trevor I. Allen
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Peak Ground Velocity ◽  
Far Field ◽  
Motion Model ◽  
Ground Acceleration ◽  
Depth Dependence ◽  
Ground Motion Model ◽  
Plate Margin ◽  
Short Period

ABSTRACT The Australian territory is just over 400 km from an active convergent plate margin with the collision of the Sunda–Banda Arc with the Precambrian and Palaeozoic Australian continental crust. Seismic energy from earthquakes in the northern Australian plate-margin region are channeled efficiently through the low-attenuation North Australian craton (NAC), with moderate-sized (Mw≥5.0) earthquakes in the Banda Sea commonly felt in northern Australia. A far-field ground-motion model (GMM) has been developed for use in seismic hazard studies for sites located within the NAC. The model is applicable for hypocentral distances of approximately 500–1500 km and magnitudes up to Mw 8.0. The GMM provides coefficients for peak ground acceleration, peak ground velocity, and 5%-damped pseudospectral acceleration at 20 oscillator periods from 0.1 to 10 s. A strong hypocentral depth dependence is observed in empirical data, with earthquakes occurring at depths of 100–200 km demonstrating larger amplitudes for short-period ground motions than events with shallower hypocenters. The depth dependence of ground motion diminishes with longer spectral periods, suggesting that the relatively larger ground motions for deeper earthquake hypocenters may be due to more compact ruptures producing higher stress drops at depth. Compared with the mean Next Generation Attenuation-East GMM developed for the central and eastern United States (which is applicable for a similar distance range), the NAC GMM demonstrates significantly higher short-period ground motion for Banda Sea events, transitioning to lower relative accelerations for longer period ground motions.

scholarly journals A Study on Microzonation of Sejong City Area by Site Amplification Caused by Gyeongju Type Earthquake

2020 ◽  
Vol 20 (6) ◽  
pp. 221-228
Author(s):  
JunSung Lee ◽  
HyungChoon Park ◽  
HyunJu Oh
Keyword(s):  
Seismic Waves ◽  
Double Resonance ◽  
Ground Vibration ◽  
Site Amplification ◽  
Resonance Phenomenon ◽  
Response Analysis ◽  
Target Area ◽  
Ground Response Analysis ◽  
Natural Period ◽  
Ground Conditions

When an earthquake occurs, ground amplification is caused by the soil. For the same earthquake, the magnitude of ground vibration experienced by buildings varies depending on the ground conditions. In this study, ground response analysis was performed for 120 locations in Sejong City, using Gyeongju earthquake waves, which reflect the characteristics of possible seismic waves in Korea. By creating a map using the Peak Ground Accelation (PGA) that the structure will experience and the ground natural period for each location, a map of the building type (building layer) that is likely to be earthquake-prone was determined based on the double resonance phenomenon, and the seismic hazard in the target area was assessed. The microzonation map based on the characteristics of these ground amplifications could be used for selecting the priority for inspection or the priority for anti-seismic reinforcement in the event of an earthquake.

Cost Savings of Implementing Site-Specific Ground Motion Response Analysis in the Design of Short-Period Mississippi Embayment Bridges

2018 ◽  
Vol 34 (3) ◽  
pp. 1155-1175
Author(s):  
Clinton M. Wood ◽  
Ethan R. B. Baker
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Design Procedure ◽  
Cost Savings ◽  
Response Analysis ◽  
Period Range ◽  
Site Specific ◽  
Motion Response ◽  
State Highway ◽  
Short Period

Deep dynamic site characterization and a site-specific ground motion response analysis (SSGMRA) were conducted for a bridge site in Monette, Arkansas. The SSGMRA indicated the design acceleration response spectrum determined using the American Association of State Highway and Transportation Officials (AASHTO) general seismic procedure could be reduced by one third for the short-period range due to attenuation of the short-period ground motions. The steel girder pile-bent bridge, originally designed using the AASHTO general seismic design procedure, was redesigned using the updated seismic demands estimated from SSGMRA. A cost-savings analysis was then conducted to determine the potential savings associated with conducting the SSGMRA. By designing based on the results of the SSGMRA, a potential gross savings of $205,000, or 7% of the original bridge construction cost, could be achieved for the study bridge. Items that contributed most to the cost savings were the pile and embankment construction.

Ground Motion at a Semi-Cylindrical Valley Partially Filled with a Crescent-Shaped Soil Layer Under Incident Plane SH Waves

2017 ◽  
Vol 11 (03) ◽  
pp. 1750007 ◽  
Author(s):  
Ning Zhang ◽  
Yufeng Gao ◽  
Denghui Dai
Keyword(s):  
Ground Motion ◽  
Soil Layer ◽  
Topographic Effects ◽  
Soil Amplification ◽  
Alluvial Valley ◽  
Sh Waves ◽  
Topographic Amplification ◽  
Incident Plane ◽  
Irregular Topography ◽  
Plane Sh Waves

To elucidate the ground motion amplification due to soil and topographic effects, an analytical formulation based on wavefunction expansion is derived for the scattering of plane SH waves by a semi-cylindrical valley partially filled with a crescent-shaped soil layer. The site responses consisting of both soil and topographic effects from the partially filled alluvial valley and the pure topographic contribution from the homogeneous valley of the same geometry are calculated and compared. It is found that the soil amplification effects are usually larger than the topographic amplification effects within the alluvial valley, while the topographic effects dominate the amplification pattern of ground motions outside the alluvial valley. Generally, the maximum soil amplification generally far outweighs the maximum topographic amplification. The material parameters and filling degree of the soil layer are found to affect the magnitude and the pattern of ground motion amplitude on the valley surface depending on the irregular topography, the frequency content and obliquity of the wave incidence.

scholarly journals Study on the influence of the seafloor soft soil layer on seismic ground motion

2021 ◽  
Vol 21 (2) ◽  
pp. 577-585
Author(s):  
Jingyan Lan ◽  
Juan Liu ◽  
Xing Song
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Response Spectrum ◽  
Soft Soil ◽  
Free Field ◽  
Soil Layer ◽  
P Wave ◽  
Response Analysis ◽  
Peak Acceleration ◽  
Seismic Response Analysis

Abstract. In the complex medium system of the sea area, the overlying seawater and the surface soft soil have a significant impact on the seafloor ground motion, which brings great seismic risk to the safety of offshore-engineering structures. In this paper, four sets of typical free-field models are constructed and established, comprising a land model, land model with surface soft soil, sea model and sea model with surface soft soil. The dynamic finite-difference method is used to carry out two-dimensional seismic response analysis of a typical free field based on the input forms of P and SV waves. By comparing the seismic response analysis results of four groups of calculation models, the effects of overlying seawater and soft soil on the peak acceleration and acceleration response spectrum are studied. The results show that when an SV wave is input, the peak acceleration and response spectrum of the surface of soft soil on the surface and the seabed surface can be amplified, while the overlying seawater can significantly reduce the ground motion. When the P wave is used, the effect of overlying seawater and soft soil on the peak acceleration and response spectrum of the surface and seabed can be ignored. The peak acceleration decreases first and then increases from the bottom to the surface, and the difference of peak acceleration calculated by four free-field models is not obvious. The results show that the overlying seawater and the surface soft soil layer have little effect on the peak acceleration of ground motion below the surface.

Sign in / Sign up

Export Citation Format

Share Document