• 한국지진공학회논문집
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• 제27권3호
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• pp.139-145
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• 2023

It is essential to determine a proper earthquake time history as a seismic load in a seismic design for a critical structure. In the code, a seismic load should satisfy a design response spectrum and include the characteristic of a target fault. The characteristic of a fault can be represented by a definition of a type of possible earthquake time history shape that occurred in a target fault. In this paper, the pseudo-basis function is proposed to be used to construct a specific type of earthquake, including the characteristic of a target fault. The pseudo-basis function is derived from analyzing the earthquake time history of specific fault harmonic wavelet transform. To show the feasibility of this method, the proposed method was applied to the faults causing the Gyeong-Ju ML5.8 and Pohang ML5.3 earthquakes.

• Earthquakes and Structures
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• 제6권4호
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• pp.375-392
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• 2014

Time history analyses have been preferred commonly in earthquake engineering area to determine earthquake performances of structures in recent years. Advances in computer technology and structural analysis have led to common usage of time history analyses. Eurocode 8 allows the use of real earthquake records as an input for linear and nonlinear time history analyses of structures. However, real earthquake records with the desired characteristics sometimes may not be found, for example depending on soil classes, in this case artificial and synthetic earthquake records can be used for seismic analyses rather than real records. Selected earthquake records should be scaled to a code design spectrum to reduce record to record variability in structural responses of considered structures. So, scaling of earthquake records is one of the most important procedures of time history analyses. In this paper, four real earthquake records are scaled to Eurocode 8 design spectrums by using SESCAP (Selection and Scaling Program) based on time domain scaling method and developed by using MATLAB, GUI software, and then scaled and real earthquake records are used for linear time history analyses of a six-storied building. This building is modeled as spatial by SAP2000 software. The objectives of this study are to put basic procedures and criteria of selecting and scaling earthquake records in a nutshell, and to compare the effects of scaled earthquake records on structural response with the effects of real earthquake records on structural response in terms of record to record variability of structural response. Seismic analysis results of building show that record to record variability of structural response caused by scaled earthquake records are fewer than ones caused by real earthquake records.

• 한국지진공학회논문집
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• 제12권5호
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• pp.31-38
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• 2008

최근 구조물의 지진해석에서 시간이력 지진해석의 필요성이 증대되고 있는데, 시간이력해석을 위해서는 최소7개의 지진기록을 사용하도록 IBC2003, ASCE와 KBC2005의 내진설계 기준에서 요구하고 있다. 시간이력 지진해석을 위해 지진기록의 선정은 주어진 대지 조건에 따른 설계스펙트럼을 만족하도록 시간이력 지진기록을 설계 지반조건과 유사한 지반에서 계측된 지진기록들 중에서 선정하거나 설계스펙트럼을 만족하는 인공지진기록을 생성하여 사용할 수 있지만, 이 연구에서는 절충적 방법으로 태평양지진연구센터(PEER) 데이터베이스에서 암반 지진기록으로 알려진 50개 계측지진기록을 이용하여 7개 인공 시간이력 지진기록을 생성하였다. 일차 조정계수를 곱한 지진응답스펙트럼이 목표설계스펙트럼에 최적합한 7개 지진기록을 선정하고, SRSS 평균값이 목표설계스펙트럼과 최소의 오차를 갖게 하는 최적합화법으로 구한 조정계수를 선정된 각 지진기록에 곱하여 7개 인공 시간이력 지진기록군을 생성하였다.

• 한국지진공학회논문집
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• 제12권1호
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• pp.89-95
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• 2008

최근까지도 많은 시간이력 지진해석이 연약지반의 증폭영향을 고려하지 않고 연약지반 위 지표면에서 기록된 지진거동으로 수행되었다. 그러나 합리적인 구조물의 지진해석을 위해서는 지반조건을 고려하고 암반지진기록을 이용하는 것이 중요하다. 이 연구에서는 연구를 위해 태평양지진연구센터(PEER)에서 제공하는 공개된 1557개의 지진기록 중에서 26개 암반지진기록을 선정하고 암반지진 기록의 특성을 분석하였다. 연구결과에 의하면, 지반조건을 고려하지 않고 지진규모로부터 지진가속도를 추정하는 것은 합리적이지 못하며, PEER 데이터베이스 암반지진기록으로는 지진가속도, 지진규모, 진앙거리 사이의 일반적인 상관관계를 추정하는 것도 어려운 것으로 평가되었다. 그러나 이 연구에서 선정한 26개 암반지진기록은 구조물-지반체계의 시간이력 지진해석을 위해 암반지진기록으로 사용할 수는 있지만, 이 지진기록을 사용할 때에도 지진가속도, 지진규모, 진앙거리 및 지반조건이 유사한 지진기록을 사용하는 것이 필요하다는 것을 확인할 수 있었다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.20-27
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• 1998

In the current seismic design codes design earthquake is usually defined as the earthquake with the 90 percent probability of not being exceeded in the life time of a structure which is assumed as 50 years equivalent to the earthquake with 475 year recurrence period. However the life time of tall building structures may be much longer than 50 yers. The current seismic design code requires the modal analysis or dynamic time history analysis for the buildings with the height exceeding a certain height limit. The objective of this study is to collect the earthquake ground motion(EQGM) which can be used for dynamic time history analysis for tall buildings. For this purpose linear elastic design response spectrum (LEDRS) in the code is scaled to account for the recurrence period of the design earthquake. The earthquake ground motions which has been recorded are calibrated to fit the scaled LEDRS. The set of calibrated EQGM can be treated as design EQGM for the design of tall building with longer lifetime than ordinary building.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.616-620
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• 2009

Modern wind turbines have been mainly erected in region where earthquake are rare or normally weak, especially Korea was thought as safety zone from earthquake. But recently, the earthquake occurs more and more frequently. So, the wind turbine design is required the structural and functional stability under the earthquake. The earthquake can influence normal operation, even if a weak earthquake. There are two ways to review the design under earthquake using Computer Applied Engineering (CAE). One is the Response Spectrum Analysis (RSA) the other is Time History Analysis (THA). In this research, dynamic response on time is obtained under the earthquake by taking into account ground accelerogram consistent with the relevant standards applied to the turbine foundation.

• Computers and Concrete
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• 제19권6호
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• pp.689-699
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• 2017

An energy-based approach for determining earthquake safety of reinforced concrete frame structures is presented. The developed approach is based on comparison of plastic energy capacities of the structures with plastic energy demands obtained for selected earthquake records. Plastic energy capacities of the selected reinforced concrete frames are determined graphically by analyzing plastic hinge regions with the developed equations. Seven earthquake records are chosen to perform the nonlinear time history analyses. Earthquake plastic energy demands are determined from nonlinear time history analyses and hysteretic behavior of earthquakes is converted to monotonic behavior by using nonlinear moment-rotation relations of plastic hinges and plastic axial deformations in columns. Earthquake safety of selected reinforced concrete frames is assessed by using plastic energy capacity graphs and earthquake plastic energy demands. The plastic energy dissipation capacities of the frame structures are examined whether these capacities can withstand the plastic energy demands for selected earthquakes or not. The displacements correspond to the mean plastic energy demands are obtained quite close to the displacements determined by using the procedures given in different seismic design codes.

• 한국지진공학회논문집
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• 제17권2호
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• pp.89-95
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• 2013

Structures in a nuclear power system are designed to be elastic even under an earthquake excitation. However a structural component such as an isolator shows inelastic behavior inherently. For the seismic assessment of nonlinear structures, response history analysis should be performed. In this study, the response of base isolation system was analyzed by response history analysis for the seismic performance assessment. Firstly, several seismic assessment criteria for a nuclear power plant structure were reviewed for the nonlinear response history analysis. Based on these criteria, the spectrum matched ground motion generation method modifying a seed earthquake ground motion time history was adjusted. Using these spectrum matched accelerograms, the distribution of displacement responses of the simplified base isolation system was evaluated. The resulting seismic responses excited by the modified ground motion time histories and the synthesized time history generated by stochastic approach were compared. And the response analysis of the base isolation system considering the different intensities in each orthogonal direction was performed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.304-311
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• 1998

An algorithm to enhance spectra matching of acceleration time history used in the seismic analysis of nuclear power plants(NPP) is proposed. The new scheme provides the solution on the highly fluctuating and over conservatism problems that happened in order to satisfy design spectrum enveloping criteria in the traditional method. To obtain optimized spectrum for a time history, a spectrum matching procedure that adapts a system identification technique is also developed. The algorithm also introduces maximum displacement control, baseline correction, clipping and raising of maximum peak of time history, and power spectral density (PSD) control of time history. It is verified through numerical examples that this new scheme can definitely generate acceleration time history, closely matching the target spectra and satisfying other stipulated requirements.

• Structural Engineering and Mechanics
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• 제69권3호
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• pp.293-306
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• 2019

In current seismic design codes, various elastic design acceleration spectra are defined considering different seismological and soil characteristics and are widely used tool for calculation of seismic loads acting on structures. Response spectrum analyses directly use the elastic design acceleration spectra whereas time history analyses use acceleration records of earthquakes whose acceleration spectra fit the design spectra of seismic codes. Due to the fact that obtaining coherent structural response quantities with the seismic design code considerations is a desired circumstance in dynamic analyses, the response spectra of earthquake records used in time history analyses had better fit to the design acceleration spectra of seismic codes. This paper evaluates structural response distributions of multi-story reinforced concrete frames obtained from nonlinear time history analyses which are performed by using the scaled earthquake records compatible with various elastic design spectra. Time domain scaling procedure is used while processing the response spectrum of real accelerograms to fit the design acceleration spectra. The elastic acceleration design spectra of Turkish Seismic Design Code 2007, Uniform Building Code 1997 and Eurocode 8 are considered as target spectra in the scaling procedure. Soil classes in different seismic codes are appropriately matched up with each other according to $V_{S30}$ values. The maximum roof displacements and the total base shears of considered frame structures are determined from nonlinear time history analyses using the scaled earthquake records and the results are presented by graphs and tables. Coherent structural response quantities reflecting the influence of elastic design spectra of various seismic codes are obtained.