• Journal of the Korean Geotechnical Society
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• v.34 no.9
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• pp.43-49
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• 2018

Seismic hazard assessments are performed on a variety of infrastructure projects. One component of a seismic hazard assessment is the attenuation relationship. Several attenuation relationships have been developed over the decades to predict peak ground acceleration under a variety of site conditions. For example, many attenuation relationships were designed to estimate peak ground acceleration, as well as other intensity measures, under a variety of soil conditions, mostly using the average shear wave velocity for the upper 30 m of earth material as a classification scheme. However, certain types of infrastructure, such as tunnels and nuclear power plants, are typically founded on and in bedrock. Using data from Japan, we developed a simple correlation to estimate peak ground acceleration for rock sites and compare the results from another popular attenuation relationship. Results indicate the popular attenuation relationship to be less than the proposed model for distances less than 200 km.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.581-586
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• 1997

The objective of this study is to investigate the behavior of a 1/5-scale 3-story nonductile reinforced concrete frame subjected to earthquake excitation. For this purpose, Taft N21E earthquake accelerogram was simulated by using 3m${\times}$5m shaking table. When the input acceleration is compared to that of output, it can be found that simulation of shaking table is excellent. From the results of test with Taft N21E earthquake accelerogram adjusted to peak ground acceleration(PGA) 0.06g and 0.12g(maximum acceleration in korea seismic code) the model responded in elastic behavior and it is found that the existing building in our country are safe against the levels of PGA 0.06g and 0.12g.

• Earthquakes and Structures
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• v.6 no.2
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• pp.141-161
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• 2014

This article presents a new generation of empirical ground motion models for the prediction of response spectral accelerations in soil conditions, specifically developed for the Vrancea intermediate-depth seismic source. The strong ground motion database from which the ground motion prediction model is derived consists of over 800 horizontal components of acceleration recorded from nine Vrancea intermediate-depth seismic events as well as from other seventeen intermediate-depth earthquakes produced in other seismically active regions in the world. Among the main features of the new ground motion model are the prediction of spectral ordinates values (besides the prediction of the peak ground acceleration), the extension of the magnitudes range applicability, the use of consistent metrics (epicentral distance) for this type of seismic source, the extension of the distance range applicability to 300 km, the partition of total standard deviation in intra- and inter-event standard deviations and the use of a national strong ground motion database more than two times larger than in the previous studies. The results suggest that this model is an improvement of the previous generation of ground motion prediction models and can be properly employed in the analysis of the seismic hazard of Romania.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.95-101
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• 2018

The objective of this study is to evaluate the liquefaction cyclic shear stress ratio considering the soil uncertainty. In this study, the probabilistic ground response analysis and the cyclic shear stress ratio analysis for the liquefaction potential evaluation are performed considering the soil variability. The statistical properties of input ground parameters were analyzed to investigate the parameters affecting the seismic response analysis. The Probabilistic analysis was carried out by Monte Carlo Simulation method. The ground response analysis was performed considering the soil variability and the probability distribution characteristics of the ground acceleration. The probability distribution of the peak ground acceleration by seismic characteristics was presented. The differences of liquefaction shear stress ratio results according to soil variability were compared and analyzed. The maximum acceleration of the ground by the deterministic method was analyzed to be overestimation of the ground amplification phenomenon. Also, the shear stress ratio was overestimated.

• Interaction and multiscale mechanics
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• v.5 no.1
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• pp.75-90
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• 2012

This paper investigates the effects of sports ground materials on the transfer characteristics of the landing impact force using a coupled foot-shoe-ground interaction model. The impact force resulting from the collision between the sports shoe and the ground is partially dissipated, but the remaining portion transfers to the human body via the lower extremity. However, since the landing impact force is strongly influenced by the sports ground material we consider four different sports grounds, asphalt, urethane, clay and wood. We use a fully coupled 3-D foot-shoe-ground interaction model and we construct the multi-layered composite ground models. Through the numerical simulation, the landing impact characteristics such as the ground reaction force (GRF), the acceleration transfer and the frequency response characteristics are investigated for four different sports grounds. It was found that the risk of injury, associated with the landing impact, was reduced as the ground material changes from asphalt to wood, from the fact that both the peak vertical acceleration and the central frequency monotonically decrease from asphalt to wood. As well, it was found that most of the impact acceleration and frequency was dissipated at the heel, then not much changed from the ankle to the knee.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• Geomechanics and Engineering
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• v.31 no.2
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• pp.183-195
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• 2022

Under the effects of the near-field earthquakes, the incident angle of the incoming wave could be different. In this study, the influences of some parameters such as incident angle, basin edge, peak ground acceleration level of the bedrock motion as well as different clay types with different consistency on the amplification behavior of the shallow basins are investigated. To attain this goal, the numerical analyses of the basins filled with three different clay types are performed using a fully nonlinear method. The two dimensional models of the basins are subjected to a set of strong ground motions with different peak ground acceleration levels and three different incident angles of 30◦, 45◦ and 90◦ with respect to the horizontal axes. The results show the dominant effect of the obliquely subjected waves at most cases. The higher effect of the 45◦ incident angle on the basin response was concluded. In the other part of this study, the spectral amplification curves of the surface points were compared. It was seen that the maximum spectral amplification of different surface points occurs at different periods. Also, it is affected by the increase in the peak acceleration level of the incoming motions.

• Earthquakes and Structures
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• v.18 no.2
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• pp.163-170
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• 2020

Floor acceleration plays a major role in the seismic design of nonstructural components and equipment supported by structures. Large floor acceleration may cause structural damage to or even collapse of buildings. For precision instruments in high-tech factories, even small floor accelerations can cause considerable damage in this study. Six P-wave parameters, namely the peak measurement of acceleration, peak measurement of velocity, peak measurement of displacement, effective predominant period, integral of squared velocity, and cumulative absolute velocity, were estimated from the first 3 s of a vertical ground acceleration time history. Subsequently, a new predictive algorithm was developed, which utilizes the aforementioned parameters with the floor height and fundamental period of the structure as the new inputs of a support vector regression model. Representative earthquakes, which were recorded by the Structure Strong Earthquake Monitoring System of the Central Weather Bureau in Taiwan from 1992 to 2016, were used to construct the support vector regression model for predicting the peak floor acceleration (PFA) of each floor. The results indicated that the accuracy of the predicted PFA, which was defined as a PFA within a one-level difference from the measured PFA on Taiwan's seismic intensity scale, was 96.96%. The proposed system can be integrated into the existing earthquake early warning system to provide complete protection to life and the economy.

• Earthquakes and Structures
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• v.10 no.6
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• pp.1391-1404
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• 2016

Peninsular Malaysia lying on the stable Sunda Plate has traditionally been considered safe with low to moderate seismicity. However, far field Sumatran mega-earthquakes have been shown to be capable of triggering ground motions felt in high rise structures in the major Malaysian cities while seismic impact from local earthquakes of moment magnitude 3.8 have reportedly induced nominal structural damages to nearby buildings. This paper presents an overview of the recent seismic activities in and around Peninsular Malaysia with reference to prominent earthquakes generated by far field interplate and local intraplate sources. Records of ground motion data and seismic hazard assessment (SHA) results available in the literature have been analyzed and discussed. The peak ground acceleration (PGA) values from historical records for few local intraplate events were observed to be higher than those for the events from Sumatran Subduction Zone. This clearly points to the need for a detailed and comprehensive SHA incorporating both far field and local sources. Such an analysis would contribute the knowledge required for secure and reliable infrastructure design and safeguard the Malaysian people and economy.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.31-43
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• 2004

Seismic risk assessment of bridge is presented using fragility curves which represent the probability of damage of a structure virsus the peak ground acceleration. In theseismic fragility analysis, the structural damage is defined using the rotational ductility at the base of the bridge pier, which is obtained through nonlinear dynamic analysis for various input earthquakes. For the assessment of seismic risk of bridge, peak ground accelerations are obatined for various return periods from the seismic hazard map of Korea, which enables to calculate the probability density function of peak ground acceleration. Combining the probability density function of peak ground acceleration and the seismic fragility analysis, seismic risk assessment is performed. In this study, seismic fragility analysis is developed as a function of not the surface motion which the bridge actually suffers, but the rock outcrop motion which the aseismic design code is defined on, so that further analysis for the seismic hazard assessment may become available. Besides, the effects of the friction pot bearings and the friction pendulum bearings on the seismic fragility and risk analysis are examined. Lastly, three regions in Korea are considered and compared in the seismic risk assessment.