• Geomechanics and Engineering
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• 제21권1호
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• pp.35-51
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• 2020

In this study, the seismic response analysis of embankment dams was investigated through numerical modeling. The seismic behavior of dams under main earthquake records and wavelet-based records were studied. Earthquake records were decomposed using de-noising method (DNM) and down-sampling method (DSM) up to five levels. In decomposition process, low and high frequencies of the main earthquake record were separated into two signals. Acceleration response, spectral acceleration, and Fourier amplitude spectrum at the crest of embankment dams under different decomposition levels were evaluated. The seismic behavior under main and decomposed earthquake records was compared. The results indicate an acceptable agreement between the seismic responses of embankment dams under wavelet-based decomposed records and main earthquake motions. Dynamic analyses show that the DNM-based decomposed earthquake records have a better performance compared to DSM-based records. DNM-based records up to level 4 and DSM-based records up to level 2 have a high accuracy in assessment of seismic behavior of embankment dams. The periods corresponding to the maximum values of acceleration spectra and the frequencies corresponding to the maximum values of Fourier amplitude spectra of embankment dam crest under main and decomposed records are in good agreement. The results demonstrate that the main earthquake records can be replaced by wavelet-based decomposed records in seismic analysis of embankment dams.

• 한국지반공학회지:지반
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• 제1권1호
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• pp.13-20
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• 1985

SHAKE 프로그램을 이용하여 연약지반으로 분포되어 있는 방콕지역에 대한 지진표답을 지표면의 가속도응답 스펙트럼과 최대 가속도로서 분석하였다. 기초암반의 최대 가속도와 부월주기가 증가됨에 따라 지표면의 최대 가속도는 증가되고 그 값은 0.3g 로 수관되었다. 아울러 지진응답 스펙트럼의 성질에 대해서도 설명되었다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.12-19
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• 1998

Response spectrum analysis method is widely used for seismic analysis of building structure. Analysis of structural vibration for equipment, machine and moving loads are executed by time history analysis. This method is very complex, difficult and tedious. In this study, maximum response of structure for this case are simply and fast. calculated by mode shape and response spectrum for excitation. At first, Response spectrum and time history analysis for some earthquake is carried and investigate the error of maximum displacement response for R. S. A. Secondly, The process for response spectrum analysis in excitation are calculated, and maximum model response are combined by CQC (Complete Quadratic Combination) methods. Finally, Combining maximum displacement response is compared with one of time history analysis.

• 한국측량학회지
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• 제33권6호
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• pp.485-495
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• 2015

The Tohoku Earthquake, which hit Japan on March 11, 2011, was a massive magnitude 9.0 earthquake, with the earthquake itself causing damage and the resulting tsunami additionally causing enormous material and human damage. The crustal deformation at that time reached a maximum of 5.24 m in Japan, Neighboring countries South Korea and China as well as the Southeast Asian region also witnessed crustal deformation ranging from a few centimeters to a few meters. The detailed analysis in this study based on data from 72 of the sites in South Korea where GNSS CORS was installed showed that South Korea underwent heterogeneous crustal deformation from the Tohoku earthquake, with a maximum of 55.5 mm, a minimum of 9.2 mm, and an average of 22.42 mm. A crustal deformation model was developed, applied, and evaluated for accuracy in this study for a prompt revision of the survey results of the control points that were changed by the crustal deformation. The survey results were revised by applying a crustal deformation model to the 1,195 unified control points installed in South Korea prior to the Tohoku earthquake. The comparison of these 1,195 points with their new survey results showed that the RMSE decreased from 14.1 to 3.4 mm and that the maximum result difference declined from 39 to 10 mm. Revision of the survey results of the control points using the crustal deformation model is deemed very useful considering that the accuracy of the survey results of the unified control points in South Korea is 3 cm.

• 한국지진공학회논문집
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• 제23권2호
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• pp.89-99
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• 2019

In order to increase the seismic safety of nuclear power plant (NPP) structures, a technique to reduce the seismic load transmitted to the NPP structure by using a seismic isolation device such as a lead-rubber bearing has recently been actively researched. In seismic design of NPP structures, three directional (two horizontal and one vertical directions) artificial synthetic earthquakes (G0 group) corresponding to the standard design spectrum are generally used. In this study, seismic analysis was performed by using three directional artificial synthetic earthquakes (M0 group) corresponding to the maximum-minimum spectrum reflecting uncertainty of incident direction of earthquake load. The design basis earthquake (DBE) and the beyond design basis earthquakes (BDBEs are equal to 150%, 167%, and 200% DBE) of G0 and M0 earthquake groups were respectively generated for 30 sets and used for the seismic analysis. The purpose of this study is to compare seismic responses and seismic fragility curves of seismically isolated NPP structures subjected to DBE and BDBE. From the seismic fragility curves, the probability of failure of the seismic isolation system when the peak ground acceleration (PGA) is 0.5 g is about 5% for the M0 earthquake group and about 3% for the G0 earthquake group.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.64-71
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• 1999

Seismicity of the Korean Peninsula shows intraplate seismicity that has irregular pattern in both time and space. Seismic data of the Korean peninsula consists of historical earthquakes and instrumental earthquakes. In this study we devide these data into complete part and incomplete part and considering earthquake size uncertainty estimate seismic hazard parameters - activity rate λ, b value of Gutenberg-Richter relation and maximum possible earthquake IMAX by statistical method in each major tectonic provinces. These estimated values are expected to be important input parameters in probabilistic seismic hazard analysis and evaluation of design earthquake.

• Earthquakes and Structures
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• 제9권4호
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• pp.875-891
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• 2015

Earthquake can occur anywhere in the world and it is essential to design important members in special structures based on maximum possible forces that can be produced in them under severe earthquake. In addition, since the earthquake is an accidental phenomena and there are no similar earthquakes, therefore the possibility of strong earthquakes should be taken into account in earthquake-resistant design of important structures. Based on this viewpoint, finding the critical acceleration which maximizes internal forces is an essential factor in structural design. This paper proposes critical excitation method to compute the critical acceleration in design of important members in special structures. These critical accelerations are computed so that the columns' internal shear force at the base of the structure at each time step is maximized under constraints on ground motion. Among computed critical accelerations (of each time step), the one which produces maximum internal shear force is selected. A numerical example presents to show the efficiency of critical excitation method in determining the maximum internal shear force and base moment under variety of constraints. The results show that these method can be used to compute the resonant earthquake which have large enough effective duration of earthquake strong motion (between 12.86 sec to 13.38 sec) and produce the internal shear force and base moment for specific column greater than the same value for selected earthquakes in constructing the critical excitation (for different cases about 2.78 to 1.29 times the San Fernando earthquake). Therefore, a group of them can be utilized in developing the response spectrum for design of special structures.

• Earthquakes and Structures
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• 제16권5호
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• pp.611-623
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• 2019

A set of mid-rise bare and uniformly infilled reinforced-concrete frame buildings are analyzed for two different seismic intensities of ground-motions (i.e., 'Design Basis Earthquake' and 'Maximum Considered Earthquake') to study their floor response. The crucial parameters affecting seismic design force for acceleration-sensitive non-structural components are studied and compared with the guidelines of the European and the United States standards, and also with the recently developed NIST provisions. It is observed that the provisions of both the European and the United States standards do not account for the effects of the period of vibration of the supporting structure and seismic intensity of ground-motions and thereby provides conservative estimates of the in-structure amplification. In case of bare frames, the herein derived component amplification factors for both the design basis earthquake and the maximum considered earthquake exceeds with their recommended values in the European and the United States standards for non-structural components having periods in vicinity of the higher modes of vibration, whereas, in case of infilled frames, component amplification factors exceeds with their recommended value in the European standard for non-structural components having periods in vicinity of the fundamental mode of vibration, and only for the design basis earthquake. As a consequence of these observations, as well as capping on the design force (in case of United states standard and NIST provisions), in case of the design basis earthquake, the combined amplification factor is underestimated for non-structural components having periods in vicinity of the higher modes of vibration of bare frames, and also for non-structural components having periods in vicinity of the fundamental mode of vibration of infilled frames. At the maximum considered earthquake demand, excepting non-structural components having periods in vicinity of the higher modes of vibration of bare frames, all provisions generally provide conservative estimates of the design floor accelerations.

• 응용통계연구
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• 제35권1호
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• pp.119-129
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• 2022

본 논문에서는 최근 경주와 포항에서 심각한 피해를 주며 발생한 지진의 규모를 과거자료에 근거한 통계적 분석방법을 통해 예측하고자 한다. 이를 위해, 조선시대 역사지진 자료중에서 연단위 밀집도가 상대적으로 높은 1392~1771년의 5년 블록 최대 규모 자료를 이용하였다. 이 자료를 기반으로 일반화 극단값(generalized extreme value) 확률분포에 기초한 극단값 이론을 이용하여 조선시대 재현기간별 지진 규모 예측 및 분석을 제시하고자 한다. 일반화 극단값 분포의 모수추정을 위해 최대가능도추정법(maximum likelihood estimation, MLE)과 L-적률추정법(L-moments estimation, LME)을 사용한다. 특히 본 논문에서는 일반화 극단값 분포가 이러한 역사지진 자료에 대한 적절한 분석 모형이 될 수 있음을 적합도 검정(goodness-of-fit test)을 통해 보인다.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.841-848
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• 2021

This study investigated the acceleration characteristics of rock slopes when earthquakes, which have not been studied much in Korea, occur. The rock slope was modeled with a similar raw of 1/20 in consideration of the height(10m), roughness, strength, and the joint dips(20°). After the completion of the model, a shaking table tests was conducted according to the magnitude of the acceleration and the type of seismic wave. The maximum acceleration was greater in the short-period seismic wave than in the long-period seismic wave, and the maximum acceleration was larger in the small acceleration. The rock slope was close to a rigid block and a structure more vulnerable to the long period wave than to the short period wave. In the event of an earthquake smaller than the domestic earthquake-resistant maximum design acceleration(0.154g), safety management of the rock slope was required.