• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.145-150
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• 1999

In the nonlinear dynamic structural analysis, the given ground excitation as an input should be well defined. Because of the lack of recorded accelerograms in Korea, it is required to generate an artificial earthquake by a stochastic model of ground excitation with various dynamic properties rather than recorded accelerograms. It is well known that earthquake motions are generally non-stationary with time-varying intensity and frequency content. Many researchers have proposed non-stationary random process models. Yeh and Wen (1990) proposed a non-stationary stochastic process model which can be modeled as components with an intensity function, a frequency modulation function and a power spectral density function to describe such non-stationary characteristics. This paper shows the process to generate nonstationary artificial earthquake ground motions considering target design response spectrum chosen by ATC14.

• Steel and Composite Structures
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• 제46권3호
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• pp.435-449
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• 2023

Time domain method and frequency domain method are commonly used in the current fatigue life calculation theory. The time domain method has complicated procedures and needs a large amount of calculation, while the frequency domain method has poor applicability to different materials and different spectrum, and improper selection of spectrum model will lead to large errors. Considering that artificial neural network has strong ability of nonlinear mapping and generalization, this paper applied this technique to random fatigue life prediction, and the effect of average stress was taken into account, thereby achieving more accurate prediction result of random fatigue life.

• 한국재난정보학회 논문집
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• 제11권1호
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• pp.35-43
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• 2015

본 연구에서는 상수도시설물에 대해 손상단계를 기능수행과 붕괴방지로 나누고, 해외실측지진과 한반도형 인공지진에 대해 각각의 최대지반가속도에 따른 취약도 함수를 도출하였다. 손상단계 및 지반가속도를 이용하여 상수도시설물의 지진파에 따른 취약도 곡선을 도출하여 비교분석하였다. 해석결과, 도복장강관과 덕타일 주철관에 한반도형인공지진을 재하하는 경우, 해외실측지진을 재하하는 경우에 비하여 중앙값이 최소 0.1에서 최대 0.4까지 작아지는 것으로 나타났다. 본 연구에서 제안된 한반도형 인공지진을 이용한 지진취약도 곡선은 국내실정에 맞는 합리적인 내진 설계에 활용될 수 있을 것이다.

• 한국지진공학회논문집
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• 제21권6호
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• pp.295-301
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• 2017

This paper relates to the study of load characteristics applicable to wind turbine generators induced by earthquakes. An artificial design earthquake wave generated through the target spectrum and the envelope function of Richter Magnitude Scale (ML) 7.0 as in ASCE4-98 was created. A simulation of earthquake loads were performed according to the design load cases (DLC) 9.5~9.7 of GL guidelines. Additionally, simulation of seismic loads experienced by Wind Turbines installed in the Gyeongju region were carried out utilizing artificial earthquakes of ML 5.8 simulating the real earthquakes during the Gyeongju Earthquakes of Sept. 2016.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.185-195
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• 2006

Nowadays it is very necessary to generate artificial accelerograms because of lack of adequate earthquake records and vast usage of time-history dynamic analysis to calculate responses of structures. According to the lack of natural records, the best choice is to use proper artificial earthquake records for the specified design zone. These records should be generated in a way that would contain seismic properties of a vast area and therefore could be applied as design records. The main objective of this paper is to present a new method based on wavelet theory to generate more artificial earthquake records, which are compatible with target spectrum. Wavelets are able to decompose time series to several levels that each level covers a specific range of frequencies. If an accelerogram is transformed by Fourier transform to frequency domain, then wavelets are considered as a transform in time-scale domain which frequency has been changed to scale in the recent domain. Since wavelet theory separates each signal, it is able to generate so many artificial records having the same target spectrum.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.767-772
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• 2002

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential in the seismic design to perform the accurate site-specific ground response analysis. In this paper, one-dimensional seismic characteristics of waste landfill are studied based on the vertical propagation of horizontal shear waves through the column of soil/waste. Seismic response analysis is peformed for short-period, long-period and artificial earthquake ground motions using a computer program for seismic response analysis of horizontally layered soil deposits. The computed peak ground accelerations are compared with the values calculated according to Korean seismic design guidelines. The analysis result shows that the long-period earthquake causes the largest peak ground acceleration while the artificial earthquake results in the smallest one.

• 한국지진공학회논문집
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• 제24권2호
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• pp.111-119
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• 2020

Recently, some of the most destructive earthquakes have occurred in South Korea since earthquake observations began in 1978. In particular, the soil liquefactions have been reported in Pohang as a result of the ML 5.4 earthquake that occurred in November 2017. Liquefaction-induced ground deformations can cause significant damage to a wide range of buildings and infrastructures. Therefore, it is necessary to take practical steps to ensure safety during an earthquake. In the current seismic design in South Korea, the Hachinohe earthquake and Ofunato earthquake recorded in Japan, along with artificial earthquakes, have been generally used for input motions in dynamic analyses. However, such strong ground motions are only from Japan, and artificial earthquake ground motions are different from real ground motions. In this study, seven ground motions are selected, including those recorded in South Korea, while others are compatible to the current design spectra of South Korea. The effects of the newly selected ground motions on site response analyses and liquefaction analyses are evaluated.

• 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.

• 한국지진공학회논문집
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• 제11권2호
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• pp.1-9
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• 2007

유전자 알고리즘을 이용하여 구조물의 지진응답해석에 사용할 인공 가속도시간이력을 작성하는 방법을 제시한다. 유전자 알고리즘을 적용하기 위해서 유전원질에 해당되는 결정변수로서 응답스펙트럼 값을 계산할 진동수를 결정하고, 산술평균 교차연산자와 산술비 돌연변이연산자를 제안한다. 이들 연산자와 전형적인 단순 교차연산자를 사용하여 설계응답스펙트럼에 부합하는 인공 지진파 작성에 사용한다. 또한 작성된 인공 가속도시간이력은 실제 계측되는 지진파의 몇 가지의 외형적 특성을 가져야 하므로 이를 고려한 인공 가속도시간이력이 작성되도록 한다. 이 외형적 특성으로는 가속도시간이력의 포락형태, 지진파의 2수평성분간의 상관관계, 지반의 최대가속도 - 최대속도 - 최대변위 관계 등이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.439-446
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• 1998

One of the most important roles in the nonlinear dynamic structural analysis is to select a proper ground excitation, which dominates the response of a structure. Because of the lack of recorded accelerograms in Korea, a stochastic model of ground excitation with various dynamic properties rather than recorded accelerograms is necessarily required. If all information is not available at site, the information from other sites with similar features can be used by the procedure of seismic hazard analysis. Eliopoulos and Wen identified the parameters of the ground motion model by the empirical relations or expressions developed by Trifunac and Lee. Because the relations used in the parameter identification are largely empirical, it is required to apply the artificial neural networks instead of the empirical model. Additionally, neural networks have the advantage of the empirical model that it can continuously re-train the new recorded data, so that it can adapt to the change of the enormous data. Based on the redefined traditional processes, three neural-networks-based models (FAS_NN, PSD_NN and INT_NN) are proposed to individually substitute the Fourier amplitude spectrum, the parameter identification of power spectral density function and intensity function. The paper describes the first half of the research for the development of Neural-Networks-based model for the generation of an Artificial earthquake and a Response Spectrum(NNARS).