• 한국구조물진단유지관리공학회 논문집
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• 제24권5호
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• pp.103-110
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• 2020

최신 내진설계기준 KDS 41 17 00에 비선형동적해석에 사용될 지반운동 선정 및 보정에 관한 절차가 반영되었으나 관련 문헌 부족으로 실무적 차원에서의 적용이 여전히 어려운 실정이다. 본 연구는 비선형동적해석 수행을 위한 지반운동을 선정하고 보정하기 위해 부지응답해석을 수행한 사례를 소개한다. 이에 근거하여, 현행 설계기준에 명기된 부지응답해석 관련 조항을 실무적용 차원에서 검토하였다. 그 결과 암반운동선정에 관한 설계조항이 지나치게 엄격하여 과도한 결과를 초래하는 것으로 나타났다. 이는 가속도 민감 구간을 포함한 관심주기범위를 지닌 저층 구조물일수록 더욱 부각되는 것으로 판단된다. 특히 표면지진파가 기준에 적합한 응답을 보였음에도 불구하고, 해석 전 절차의 암반운동선정과 관련된 조항으로 인해 해석 후 절차와 관계없이 지진파를 다시 선정 및 보정해야만 했다. 또한, 연약지반이거나 해당 지반에 강한 지진이 발생하는 경우에는 지반물성과 적절한 해석 기법을 올바르게 선정하기 위해 더욱 엄격한 조사가 선행되어야 한다고 판단된다. 지반물성과 해석기법에 관한 신뢰도가 조금이라도 문제가 있다면 설계용도로 사용하기에 부적합한 결과를 초래할 수 있기 때문이다.

• 한국지구과학회지
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• 제28권2호
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• pp.179-186
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• 2007

응답스펙트럼은 내진설계에 있어서 중요한 기초자료의 하나이다. 응답스펙트럼을 얻기 위하여, 한반도에서 발생하는 지진들의 지진원 특성에 근거하여 다수의 강진동을 Boore(2005)에 의해 개발된 컴퓨터 프로그램 SMSIM을 사용하여 모사하였다. 여러 연구결과들에 대한 충분한 검토를 통하여, 모사에 필요한 입력자료들을 선정하였다. 모사된 강진동으로부터 얻은 응답스펙트럼은 가속도 1.0 g에 대하여 정규화하여 미국 원자력위원회(1973)의 표준응답스펙트럼과 비교하였다. 이 연구에서 얻어진 응답스펙트럼의 스펙트럼 진폭은 대략 10 Hz 이상의 고주파 대역에서 표준 응답스펙트럼 값에 비하여 큰 것으로 나타났다. 또한 응력강하량의 변화에 따른 응답스펙트럼의 변화를 평가하였다. 그 결과 큰 응력강하량에 대한 응답스펙트럼의 스펙트럼 진폭은 저주파 범위내에서 큰 값을 나타냄을 제시하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.42-50
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• 2002

The duration and H/V ratio(the amplitude ratio of the horizontal to vertical components) of ground motions caused by earthquakes in southern Korea are analyzed. Total 329 seismograms of horizontal component recorded at hypocentral distances of 10 to 350 km from 27 earthquakes with local magnitude 2 to 4 are used for the analysis. Simplified relation between the duration of ground motion( $T_{d}$) and the ratio($\chi$) of Arias intensity( $I_{A}$) and squared maximum acceleration($\alpha$$_{max}$$^{2}$) is determined to be $T_{d}$ = 3.423$\chi$$^2$+ 8.200$\chi$ + 0.029, which is useful for the estimation of the duration in southern Korea. There are three distinct distance ranges with different linear variations of the duration in hypocentral distance. They are distance intervals of 10~80km, 80~140km, and the distance greater than 140km. The duration in southern Korea shows clear proportionality to the local magnitude at magnitudes greater than 3.1. The value 1.37 of the H/V ratio obtained in southern Korea is similar to the value 1.4 of ENA(Eastern North America). The H/V ratio in southern Korea increases in the frequency range from 0.3 to 10Hz. The duration and H/V ratio of ground motions derived in this study could be used in the stochastic simulation of strong ground motion.ion.n.n.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.105-116
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• 2018

The objective of this study is to investigate the response reducing effect of a seismic isolation system installed between 300m dome and supports under both horizontal and vertical seismic ground motion. The time history analysis is performed to investigate the dynamic behavior of single layer lattice domes with and without a lead rubber bearing seismic isolation system. In order to ensure the seismic performance of lattice domes against strong earthquakes, it is important to investigate the mechanical characteristics of dynamic response. Horizontal and vertical seismic ground motions cause a large asymmetric vertical response of large span domes. One of the most effective methods to reduce the dynamic response is to install a seismic isolation system for observing seismic ground motion at the base of the dome. This paper discusses the dynamic response characteristics of 300m single layer lattice domes supported on a lead rubber seismic isolation device under horizontal and vertical seismic ground motions.

• Structural Engineering and Mechanics
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• 제39권6호
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• pp.877-893
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• 2011

Response spectra of earthquake ground motions are important in the earthquake-resistant design and reliability analysis of structures. The formulation of the response spectrum in the frequency domain efficiently computes and evaluates the stochastic response spectrum. The frequency information of the excitation can be described using different functional forms. The shapes of the calculated response spectra of the excitation show strong magnitude and site dependency, but weak distance dependency. In this paper, to compare the effect of the earthquake ground motion variables, the contribution of these sources of variability to the response spectrum's uncertainty is calculated by using a stochastic analysis. The analytical results show that earthquake source factors and soil condition variables are the main sources of uncertainty in the response spectra, while path variables, such as distance, anelastic attenuation and upper crust attenuation, have relatively little effect. The presented formulation of dynamic structural response in frequency domain based only on the frequency information of the excitation can provide an important basis for the structural analysis in some location that lacks strong motion records.

• 한국지진공학회논문집
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• 제24권2호
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• pp.59-65
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• 2020

The empirical Green's function method is applied to the foreshock and the mainshock of the 2016 Gyeongju earthquake to simulate strong ground motions of the mainshock and scenario earthquake at seismic stations of seven metropolises in South Korea, respectively. To identify the applicability of the method in advance, the mainshock is simulated, assuming the foreshock as the empirical Green's function. As a result of the simulation, the overall shape, the amplitude of PGA, and the duration and response spectra of the simulated seismic waveforms are similar with those of the observed seismic waveforms. Based on this result, a scenario earthquake on the causative fault of Gyeongju earthquake with a moment magnitude 6.5 is simulated, assuming that the mainshock serves as the empirical Green's function. As a result, the amplitude of PGA and the duration of simulated seismic waveforms are significantly increased and extended, and the spectral amplitude of the low frequency band is relatively increased compared with that of the high frequency band. If the empirical Green's function method is applied to several recent well-recorded moderate earthquakes, the simulated seismic waveforms can be used as not only input data for developing ground motion prediction equations, but also input data for creating the design response spectra of major facilities in South Korea.

• 한국지진공학회논문집
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• 제25권5호
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• pp.223-232
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• 2021

The spatial variation characteristics of seismic motions at the nuclear power plant's site and structures were analyzed using earthquake records obtained at the Fukushima nuclear power plant during the Great East Japan Earthquake. The ground responses amplified as they approached the soil surface from the lower rock surface, and the amplification occurred intensively at about 50 m near the ground. Due to the soil layer's nonlinear characteristics caused by the strong seismic motion, the ground's natural frequency derived from the response spectrum ratio appeared to be smaller than that calculated from the shear wave velocity profile. The spatial variation of the peak ground acceleration at the ground surface of the power plant site showed a significant difference of about 0.6 g at the maximum. As a result of comparing the response spectrums at the basement of the structure with the design response spectrum, there was a large variability by each power plant unit. The difference was more significant in the Fukushima Daiichi site record, which showed larger peak ground acceleration at the surface. The earthquake motions input to the basement of the structure amplified according to the structure's height. The natural frequency obtained from the recorded results was lower than that indicated in the previous research. Also, the floor response spectrum change according to the location at the same height was investigated. The vertical response on the foundation surface showed a significant difference in spectral acceleration depending on the location. The amplified response in the structure showed a different variability depending on the type of structure and the target frequency.

• 한국강구조학회 논문집
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• 제16권1호통권68호
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• pp.145-153
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• 2004

기존교량의 내진성능개선 및 신설교량의 지진보호에 납-고무 베어링은 좋은 효과를 보여주고 있다. 그러나 납-고무 베어링은 사용상에 있어 문제점이 있으며, 이를 개선하기 위하여 형상기억합금(shape memory alloy)을 이용한 면진장치를 본 연구에서 제시하였다. 3경간 연속 고속도로 강교량의 지진해석을 통하여 납-고무베어링과 고무베어링 및 형상기억합금 와이어와의 조합 면진장치의 지진거동을 비교하였다. 해석결과 형상기억합금 와이어+고무베어링 시스템이 납-고무베어링과 거의 유사한 거동을 보여주었으며, 특히 제시된 면진장치는 상대변위의 제어 및 잔류변형에 있어 기존의 납-고무 베어링에 비해 성능이 우수했다.

• 대한토목학회논문집
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• 제13권2호
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• pp.111-120
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• 1993

본 논문은 에너지 분산 장치의 일종인 점탄성 감쇠기를 설치한 건물의 거동에 관한 실험 및 해석적 연구이다. 점탄성 감쇠기는 강지진 하중에 의하여 건물에 발생한 과도한 진동을 감소시키는데 효과적이다, 모드 변형에너지법을 이용하여 감쇠기에 의해 증가된 등가구조감쇠를 성공적으로 예측할 수 있으며, 따라서 점탄성 감쇠기를 설치한 건물의 지진 응답이 일반적인 모드 해석기법을 이용한 수치 모형 해석에 의해 정확히 예측된다. 이러한 결과를 토대로, 점탄성 감쇠기를 설치한 건물에 대한 설계 방법을 제시한다. 이 설계 방법은 일반적인 건물의 설계에 감쇠비라는 설계 요소를 추가함으로써 가능해진다.

• Earthquakes and Structures
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• 제7권3호
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• pp.365-384
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• 2014

The intensity of a ground motion can be measured by a number of parameters, some of which might exhibit robust correlations with the damage of structures subjected to that motion. In this study, 204 near-fault pulse-type records are selected and their seismic parameters are determined. Time history and damage analyses of a tested 3-storey reinforced concrete frame representing for low-rise reinforced concrete buildings subjected to those earthquake motions are performed after calibration and comparison with the available experimental results. The aim of this paper is to determine amongst several available seismic parameters, the ones that have strong correlations with the structural damage measured by a damage index and the maximum inter-story drift. The results show that Velocity Spectrum Intensity is the leading parameter demonstrating the best correlation, followed by Housner Intensity, Spectral Acceleration and Spectral Displacement. These seismic parameters are recommended as reliable parameters of near-fault pulse-type motions related to damage potential of low-rise reinforced concrete structures. The results also reaffirm that the conventional and widely used parameter of Peak Ground Acceleration does not exhibit a good correlation with the structural damage.