• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.462-465
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• 2011

본 논문에서는 유한요소모델을 사용하여 원자력 발전용 해수 여과장치에 대한 동적 내진해석을 수행하였다. 장치의 검증을 위해서 운전기준지진(Operating Basis Earthquake, OBE)과 안전정지지진(Safe Shutdown Earthquake, SSE)이 설계하중으로 작용하였을 때 부재에 미치는 영향을 평가하였다. 해석대상은 유한요소법을 사용하여 수학적 모델링을 완성하였고, 층응답스펙트럼(Floor Response Spectrum, FRS)에 따른 지진하중과 사하중등을 적용하여 해석을 수행하였다. 해석된 해수여과장치의 최대변위는 OBE 조건에서 2.5 mm 이고, SSE 조건에서 최대변위는 4.6 mm 이다. 최대응력은 OBE 조건에서 24 MPa, SSE 조건에서 44 MPa이며, 이 값은 재료의 항복강도의 각각 18%, 27% 수준이다. 이에 따라 지진하중조건에 따른 해수여과장치의 구조적 안전성이 제시되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.67-81
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• 2000

서해대교는 국내에 교량구조물에 관한 내진설계가 도입되기 전 설계된 교량으로서 현재 내진설계 규준에 적합하지 않은 종방향철근 및 횡방향 철근이 겹침이음된 중공육각형 단면의 철근콘크리트 기둥으로 이미 시공이 완료된 상태이다. 최근, 지진에 대한 사회적 관심이 대두됨으로서 내진 설계 규준에 적합하지 않은 철근상세를 가지 서해대교 PSM교 교각의 내진성능이 의문시되었다. 따라서, 비내진 철근상세를 가진 서해대교 PSM교 교각의내진성능 평가를 위하여 교각의 축소모형 실험을 수행하였으며, 실험결과 종방향철근 겹침이음이 교각의 전체적인 내진거동에는 큰 영향을 미치지 않으며 기대 이상의 연성을 발휘할 수 있는 것으로 나타났다. 본 논문에서는 축소모형 실험결과에 의한 시험체의 파괴양상, 유효강성, 연성, 응답수 정계수 및 등가점성감쇠비를 분석하였으며, 아울러 가속도변위 응답스펙트럼을 이용하여 서해대교 PSM교 교각의 내진성능을 평가하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.774-777
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• 2010

본 논문에서는 MR 감쇠기의 비선형 특성을 등가의 선형감쇠로 치환하기 위한 방법으로 Newmark와 Hall이 제안한 감쇠계수를 이용하였다. 응답스펙트럼의 감쇠율을 나타내는 감쇠기계수는 구조물의 최대변위를 이용하여 등가감쇠비를 추출할 수 있다는 장점을 가지고 있다. 하지만 이러한 응답스펙트럼은 구조물에 작용하는 지진하중의 특성에 따라 경향이 달라진다. 본 논문에서는 기존의 등가감쇠비 산정식을 수정하여 제안하고, 지진하중 특성에 따른 등가감쇠비의 변화를 살펴보았다. MR 감쇠기의 등가감쇠비는 가진하중과 최대마찰력의 비율에 따라 결정되며, 장주기 구조물의 경우 등가감쇠비가 감소한다. MR 감쇠기의 점성은 마찰감쇠와의 상호작용에 의해 단순한 산술합 이상의 감쇠비 증가 효과를 가진다.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.453.2-453.2
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• 2004

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4_1
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• pp.9-21
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• 1992

The effectiveness of the isolation system installed at the base of the primary structure and at the support of the substructure mounted on the primary structure is evaluated for reducing of structural responses under different earthquakes in this paper. The structural responses are analyzed to identify its behavior due to the input motion characteristics such as various peak acceleration and frequency content. Three analytical models are used to evaluate the effectiveness of the isolation system in this study as follows: fixed-base primary structure with support-fixed substructure, base-isolated primary structure with support-fixed substructure, and fixed-base primary structure with support-isolated substruciure. A computer code (KBISAP) is used for numerical integration of equation of motion considering the interaction between the primary structure and the secondary structure. The matrix condensation technique and constant average acceleration method are utilized in this program. And also, the effective stiffness of the base-isolator on reducing the structural response are evaluated for various earthquakes through the relationship of the acceleration - displacement.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.1-13
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• 2012

Seismic fragility functions are derived for probabilistic evaluation of seismic control performance of energy dissipation devices installed in reinforced concrete structures. Displacement-dependent dampers are added to the nonlinear single-degree-of-freedom systems with different natural periods and hysteretic characteristics of which stiffness and strength has uncertainty. Nonlinear time history analysis is conducted for those SDOF systems and the result is processed statistically to obtain seismic fragility functions in the form of log normal distribution. Variation of seismic fragility functions for different parameters of SDOF systems and dampers are investigated and the seismic control performance is assessed probabilistically.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.57-66
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• 2008

An experimental study was performed to evaluate seismic reduction performance and applicability of 3-dimensional floor isolation system to the main control room of nuclear power plant. A friction pendulum system(FPS) and air spring were designed and fabricated for 3-dimensional floor isolation system. Two kind of the partial experimental model of a main control room attached to the FPS and air spring were tested on the shaking table. The experimental model consisted of a control panel, a $2.5m{\times}2.5m$ access floor, four FPS and air springs. The artificial time histories based on the vertical and horizontal floor response spectrums(OBE, SSE) of the main control room were used as the earthquake input signals in the test. Compared to non-isolated system, the seismic response of experimental models using 3-dimensional floor isolation system were shown considerable seismic reduction performance.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.806-812
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• 2020

Purpose: This is aimed to evaluate the seismic fragility of curved bridge structure with I-shape girder subjected to 12 high frequency ground motions based on Gyeongju earthquake. Method: The linear elastic finite element model of curved bridge with I-Shape cross section was constructed and them linear elastic time history analyses were performed using the 12 artificial ground motions. Result: It was found that displacement response(LS1, LS2) was failed after PGA 0.1g and the stress response also showed failure after PGA 0.2g. Conclusion: The curved bridge with I-shape girder was sensitive to high frequency earthquakes.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.57-66
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• 2015

Empirical seismic displacement equations based on the Newmark sliding block method are widely used to develop seismic landslide hazard map. Most proposed equations have been developed for embankments and landfills, and do not consider the dynamic response of sliding block. Therefore, they cannot be applied to Korean mountain slopes composed of thin, uniform soil-layer underlain by an inclined bedrock parallel to the slope. In this paper, a series of two-dimensional dynamic nonlinear finite difference analyses were performed to estimate the permanent seismic slope displacement. The seismic displacement of mountain slopes was calculated using the Newmark method and the equivalent acceleration time history. The calculated seismic displacements of the mountain slopes were compared to a widely used empirical displacement model. We show that the displacement prediction is significantly enhanced if the slope is modeled as a flexible sliding mass and the amplification characteristics are accounted for. Regression equation, which uses PGA, PGV, Arias intensity of the ground motion and the fundamental period of soil layer, is shown to provide a reliable estimate of the sliding displacement. Furthermore, the empirical equation is shown to reliably predict the hazard category.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.5
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• pp.33-39
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• 2010

This study develops an approximate procedure for incremental dynamic analysis (IDA) using modal pushover analysis (MPA) with empirical equations of the inelastic displacement ratio ($C_R$) and the collapse strength ratio ($R_C$). By using this procedure, it is not required to conduct linear or nonlinear response history analyses of multi- or single- degree of freedom (MDF) systems. Thus, IDA curves can be effortlessly obtained. For verification of the proposed procedure, the 6-, 9- and 20-story steel moment frames are tested under an ensemble of 44 ground motions. The results show that the MPA-based IDA with empirical equations of $C_R$ and $R_C$ produced accurate IDA curves of the MDF systems. The computing time is almost negligible compared to the exact IDA using repeated nonlinear response history analysis (RHA) of a structure and the original MPA-based IDA using repeated nonlinear RHA of modal SDF systems.