Student Zone

2021 ◽  
Vol 40 (5) ◽  
pp. 386-387
Author(s):  
Ravi Pangeni
Keyword(s):  
Earthquake Engineering ◽  
Site Effects ◽  
Geotechnical Earthquake Engineering ◽  
Site Characteristics ◽  
Seismic Site Effects ◽  
Hands On ◽  
Basin Geometry ◽  
Student Training ◽  
Microtremor Measurements ◽  
Effects Assessment

A student training program, Engineering Seismology and Seismic Microzonation for Seismic Site Effects Assessment, was held 18–22 January 2020 in Lalitpur, Nepal. It was created through the collaboration of Thammasat University and Tribhuvan University, with support from Geoscientists Without Borders® (GWB). The goal of the program was to connect students with modern geophysical instrumentation and software through training. It specifically advanced theoretical and hands-on field-based knowledge pertaining to geotechnical earthquake engineering aspects and applications. The training served as part of a broader GWB project, Seismic Site Effects Study in Nepal, encompassing basin geometry, site characteristics, and the study of seismic site effects through microtremor measurements in Kathmandu Valley.

scholarly journals Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects

2018 ◽  
Vol 7 (9) ◽  
pp. 375 ◽  
Author(s):  
Han-Saem Kim ◽  
Chang-Guk Sun ◽  
Hyung-Ik Cho
Keyword(s):  
Site Effects ◽  
Focal Depth ◽  
Earthquake Hazard ◽  
Earthquake Damage ◽  
Site Classification ◽  
Topographical Effects ◽  
Seismic Site Effects ◽  
Moderate Earthquake ◽  
Seismic Amplification ◽  
Earthquake Moment

The 2017 Pohang earthquake (moment magnitude scale: 5.4) was South Korea’s second strongest earthquake in decades, and caused the maximum amount of damage in terms of infrastructure and human injuries. As the epicenters were located in regions with Quaternary sediments, which involve distributions of thick fill and alluvial geo-layers, the induced damages were more severe owing to seismic amplification and liquefaction. Thus, to identify the influence of site-specific seismic effects, a post-earthquake survey framework for rapid earthquake damage estimation, correlated with seismic site effects, was proposed and applied in the region of the Pohang earthquake epicenter. Seismic zones were determined on the basis of ground motion by classifying sites using the multivariate site classification system. Low-rise structures with slight and moderate earthquake damage were noted to be concentrated in softer sites owing to the low focal depth of the site, topographical effects, and high frequency range of the mainshocks.

scholarly journals Influence of Structure on the Aseismic Stability and Dynamic Responses of Liquefiable Soil

2021 ◽  
Author(s):  
Pengfei Dou ◽  
Chengshun Xu ◽  
Xiuli Du ◽  
Su Chen
Keyword(s):  
Earthquake Engineering ◽  
Damping Ratio ◽  
Free Field ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Seismic Stability ◽  
Geotechnical Earthquake Engineering ◽  
Liquefiable Soil ◽  
Porewater Pressure ◽  
Lateral Displacements

Abstract In previous major earthquakes, the damage and collapse of structures located in liquefied field which caused by site failure a common occurrence, and the problem of evaluation and disscusion on site liquefaction and the seismic stability is still a key topic in geotechnical earthquake engineering. To study the influence of the presence of structure on the seismic stability of liquefiable sites, a series of shaking table tests on liquefiable free field and non-free field with the same soil sample was carried out. It can be summarized from experimental results as following. The natural frequency of non-free field is larger and the damping ratio is smaller than that of free field. For the weak seismic loading condition, the dynamic response of sites show similar rules and trend. For the strong ground motion condition, soils in both experiments all liquefied obviously and the depth of liquefaction soil in the free field is significantly greater than that in the non-free field, besides, porewater pressure in the non-free field accumulated relately slow and the dissapited quikly from analysis of porewater pressure ratios(PPRs) in both experiments. The amplitudes of lateral displacements and acceleration of soil in the non-free field is obviously smaller than that in the free field caused by the effect of presence of the structure. In a word, the presence of structures will lead to the increase of site stiffness, site more difficult to liquefy, and the seismic stability of the non-free site is higher than that of the free site due to soil-structure interaction.

Engineering observations on ground motion at the Van Norman Complex after the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S333-S349 ◽  
Author(s):  
J. P. Bardet ◽  
C. Davis
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Northridge Earthquake ◽  
Peak Acceleration ◽  
Geotechnical Earthquake Engineering ◽  
1994 Northridge Earthquake

Abstract During the 1994 Northridge earthquake, the Van Norman Complex yielded an unprecedented number of recordings with high acceleration, in the close proximity of the fault rupture. These strong-motion recordings exhibited the pulses of the main event. One station recorded the largest velocity ever instrumentally recorded (177 cm/sec), resulting from a 0.86 g peak acceleration with a low frequency. Throughout the complex, the horizontal accelerations reached peak values ranging from 0.56 to 1.0 g, except for the complex center, where the peak acceleration did not exceed 0.43 g. The vertical acceleration reached maximum peak values comparable with those of the horizontal acceleration. The acceleration response spectra in the longitudinal and transverse directions were significantly different. Such a difference, which is not yet well documented in the field of geotechnical earthquake engineering, indicates that the amplitude and frequency content of the ground motion was directionally dependent in the Van Norman Complex.

DEM Simulations in Geotechnical Earthquake Engineering Education

2012 ◽  
pp. 100-109
Author(s):  
J. S. Vinod
Keyword(s):  
Engineering Education ◽  
Granular Materials ◽  
Earthquake Engineering ◽  
Laboratory Experiments ◽  
Computational Models ◽  
Cyclic Behavior ◽  
Advanced Mathematics ◽  
Loading Conditions ◽  
Geotechnical Earthquake Engineering ◽  
Element Method

Behaviour of geotechnical material is very complex. Most of the theoretical frame work to understand the behaviour of geotechnical materials under different loading conditions depends on the strong background of the basic civil engineering subjects and advanced mathematics. However, it is fact that the complete behaviour of geotechnical material cannot be traced within theoretical framework. Recently, computational models based on Finite Element Method (FEM) are used to understand the behaviour of geotechnical problems. FEM models are quite complex and is of little interest to undergraduate students. A simple computational tool developed using Discrete Element Method (DEM) to simulate the laboratory experiments will be cutting edge research for geotechnical earthquake engineering education. This article summarizes the potential of DEM to simulate the cyclic triaxial behaviour of granular materials under complex loading conditions. It is shown that DEM is capable of simulating the cyclic behavior of granular materials (e.g. undrained, liquefaction and post liquefaction) similar to the laboratory experiments.

Utilization of Classification Techniques for the Determination of Liquefaction Susceptibility of Soils

2016 ◽  
pp. 124-160 ◽  
Author(s):  
J. Jagan ◽  
Prabhakar Gundlapalli ◽  
Pijush Samui
Keyword(s):  
Support Vector Machine ◽  
Earthquake Engineering ◽  
Relevance Vector Machine ◽  
Least Square ◽  
Support Vector ◽  
Ground Acceleration ◽  
Geotechnical Earthquake Engineering ◽  
Liquefaction Susceptibility ◽  
Input Variables

The determination of liquefaction susceptibility of soil is a paramount project in geotechnical earthquake engineering. This chapter adopts Support Vector Machine (SVM), Relevance Vector Machine (RVM) and Least Square Support Vector Machine (LSSVM) for determination of liquefaction susceptibility based on Cone Penetration Test (CPT) from Chi-Chi earthquake. Input variables of SVM, RVM and LSSVM are Cone Resistance (qc) and Peak Ground Acceleration (amax/g). SVM, RVM and LSSVM have been used as classification tools. The developed SVM, RVM and LSSVM give equations for determination of liquefaction susceptibility of soil. The comparison between the developed models has been carried out. The results show that SVM, RVM and LSSVM are the robust models for determination of liquefaction susceptibility of soil.

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