• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.19-26
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• 2007

This paper presents the results of experimental studies of the mechanical characteristics of the Coil Spring and Viscous Damper system. The Coil Spring and Viscous Damper systems were selected for the isolation of Emergency Diesel Generator (EDG) which is located in Nuclear Power Plant (NPP). The Coil Spring and Viscous Damper systems were developed for the operating vibration isolation and seismic isolation for scaled Model EDG System. The damping properties of the viscous damper changes as the variation of velocity. Through this research nonlinear damping characteristics and the effective stiffness of coil spring and viscous damper system were evaluated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.127-134
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• 2008

For more districted seismic design and attemped multi-bridge continuity, the existing seismic design is difficulted to treat seismic activity. So, many company applied multi-fixed point and damper or isolator, which is effective for decreasing seismic energy, on period shift, decentralization and damping. But, there is hard to design special bridge with adjusted seismic system because of absence seismic device and insufficient design experience. Therefore, the study on behavior characteristics of designed bridge with various seismic device is performed to utilize the result of this for selection of adequate seismic device.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.45-48
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• 2008

Under earthquake loads, the columns on the lower stories carry large axial forces and horizontal forces as the earthquake loads are acting horizontally and vertically on the building. To distribute the energy entered into the building under earthquakes according to the plastic deformation of the members, it is safer and more economic to persuade plastic hinge to occur in the beams rather than on the columns. However, it is unavoidable to have plastic hinge occurring on the columns when it is applied on both of the main axes of the building, which results in high shear force on the column end, and reinforced concrete column may result in sudden brittle failure due to bending moment and shear force. To increase restriction of the reinforced concrete column on the horizontal forces, this study uses repetitive loading experiments with different amount of shear reinforcement, and analyzes and compares the structural safety and behaviour of the reinforced test materials.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.11-21
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• 1998

During an earthquake, there are three main components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation induced by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the soil plugs in open-ended pie piles installed at offshore sites. In this study, seaquake excitation induced by the vertical ground shaking was simulated by pulsing the water pressure at the seabed. During a seaquake, due to the induced excess porewater pressure and pressure gradients in the soil, the capacity of open-ended pipe piles installed in a simulated sea depth of greate than 220 m was reduced serevely and the soil plugging resistance was degraded by more than 80% The soil plug was failed because of eh upward seepage forces that developed in the soil plug due to excess pore water pressure produced in the bottom of the soil plug during the seaquake, The compressive capacity of ar open-ended pile in a simulated sea depth of less than 220 m was reduced only by about 10% and the soil plug resistance was degraded by less than 5%.s than 5%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.13-22
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• 1998

This paper summarizes a study on the application of the friction pendulum system in bridge seismic isolation. Shaking table tests have been carried out on a model structure isolated with F.P.S and the obtained structural responses are compared to those of non-isolated. It can be concluded the F.P.S increases the earthquake resistance capacity of the isolated structure. It is also found that the stiffness of bearing, being controlled by the radius of curvature of the spherical sliding interface, is unaffected by the amplitude of the input excitation. Furthermore, the coefficient of sliding friction is velocity dependent so that in weak excitation the sliding velocity is low and, accordingly, the mobilized friction force is less than the one mobilized in strong excitation. Also, the frictional properties of the bearings remain markedly stable after extensive testing, and the permanent displacements are small and not cumulative in successive earthquakes.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.57-63
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• 2008

This paper presents a seismic response prediction method using vibration tests of cabinet-type electrical equipment installed in a nuclear power plant. The proposed method consists of three steps: 1) identification of earthquake-equivalent forces based on lumped-mass system idealization, 2) identification of a state-space-equation model relating input-output measurements obtained from the vibration tests, 3) seismic prediction using the identified earthquake-equivalent forces and the identified state-space-equation. The proposed method is advantageous compared to other methods based on FEM (finite element method) model update, since the proposed method is not influenced by FEM modeling errors. Through a series of numerical verifications on a frame model and 3-dimensional shell model, it was found that the proposed method could be used to accurately predict the seismic responses, even under considerable measurement noise conditions. Experimental validation is needed for further study.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.33-47
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• 2001

성능에 기초한 내진설계에서는 구조물이 보유하고 있는 능력을 효과적으로 파악하기 위해서 비선형 정적 해석이 적용되고 있다. 그러나 비선형 정적해석은 고차모드에 대한 효과를 고려하지 못함으로써 고층구조물이나 비정형 구조물과 같은 경우에는 정확한 비선형 지진응답의 산정과 내진성능을 평가하는데 문제점을 가지고 있다. 본 연구에서는 건축구조물의 선형 및 비선형 지진응답 평가를 위하여 응답 스펙트럼해석을 통하여 얻어지는 층전단력으로부터 층하중을 산정하는 유사동적해석법이 적용되었다. 제안된 방법을 비선형 정적 해석에 적용하여 구조물의 비선형 자동응답을 비선형 시간이력해석의 결과와 비교하였다. 기존의 층분포하중에 의한 비선형 지진응답과 비교하였으며, 제안된 방법에 의한 지진 응답이 구조물의 비선형 거동특성을 가장 정확하게 표현하였다. 그러므로 본 연구에서 제안된 방법을 사용하여 비선형 정적 해석을 수행한다면 비교적 명확한 건축물의 비선형 거동특성과 내진성능을 평가할 수 있을 것으로 판단된다.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.123-133
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• 2004

The magnitudes of wall thrust acting on quay walls can easily vary due to the development of excess pore pressure in backfill. In this research, a new displacement model was proposed to predict the displacement of the wall considering such magnitude variations of the wall thrust. This model is based on Newmark sliding block concept. The magnitude variation of the wall thrust is modelled by varying the magnitude of yield acceleration. The parametric study was performed to analyze the effects of input parameters on the seismic displacement of the wall, and the validity of this model was verified by comparing its predicted displacements with those of Is shaking table tests.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.25-36
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• 2000

본 논문에서는 구조물이 과도한 기진력을 받을 때에 구조물의 진동 제어를 위하여 제안 되어진 여러 가지 포화 제어 알고리듬들의 유용성을 실제적인 관점에서 살펴보았다 제안된 포화 제어 알고리듬 중세서 수정된 뱅뱅 제어 알고리듬이 매우 유용한 것임을 확인할 수 있었으나 이는 제어력 파형 결정 파라미터의 어떤 범위내에서만 효과적이며 그 범위를 넘어서는 경우에 있어서는 제어기를 불안정하게 할 수 있음을 확인할 수 있었다 따라서 수정된 뱅뱅 제어 알고리듬의 적용시에 과도한 외부 기진력에 대하여 제어기의 안정적인 작동에 의한 구조물의 진동제어효과를 얻기 위해서 제어력 파형 파라미터를 과도 기진력의 크기에 따라 변화시키는 적응형의 방법을 제안하였고 이의 유용성을 수치실험 및 유압식 질량 감쇠기를 장착한 축소 구조물 검증 실험을 통하여 확인하였다.