• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.269-273
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• 2015

처음 에디슨 경진대회를 준비할 때 업로드 되어 있는 다양한 프로그램을 보면서 어떤 주제를 선정할 지 고민을 하던 중, 눈에 들어온 프로그램은 서울대학교에서 제작한 Co-rotational Plane beam-Dynamic tip load이란 프로그램이었다. 위 프로그램은 한쪽 단이 고정된 외팔보(cantilever beam)의 끝단에 하중을 시간에 관련된 함수(sin, cos)로 주어 각 절점에서의 변위(X, Y), 속도 그리고 가속도를 알려주는 프로그램이다. 우리는 이 프로그램을 이용해서 외팔보 끝단의 진동 형태와 주기가 어떤 요인(단면의 모양, 재료의 성질, 가하는 하중의 진동수 등)에 의해서 변하는지 분석할 수 있었다. 거기서 더 나아가 하중을 실제 지진상황에서의 크기와 유사하게 주고 위 프로그램에서의 보의 거동(진동 주기, 진동 변위 등)을 건물의 거동이라 가정했을 때 면진 주기를 얼마로 설정해야하는지도 알 수 있었다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.65-74
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• 2019

This study presents the optimal isolation period according to the number of vertically expended stories in order to provide the basic data for the application of the seismic isolation system in the vertically expended remodeling of the aged apartment. As a result of the structural analysis, the isolation period should be at least twice the primary structure in three-story vertical expansion, three times in two-story expansion, and four times in one-story expansion for the effective application of the isolation system. On the basis of the result, the efficacy of an isolation system for the actual apartment structure, which is three-story vertically expended, was analytically verified. The maximal acceleration response on the top floor reduced by 70% and 65% of the non-isolated structure in the X and Y directions respectively. Additionally, the base shear force decreased by 30% in the both directions, compared to the non-isolated structure.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.712-722
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• 2020

Purpose: The damage from earthquakes with a magnitude of 5.0 or greater Korea has increased in South Korea. When a earthquake occurs, internal facilities and electric equipment besides urban structures will be damaged. Thus, in this paper, an earthquake-induced seismic isolation device with double slip fiction surfaces which can reduce the damage of electric power equipment such as distribution panel and then the seismic performance was evaluated. Method: To evaluate the seismic performance shaking table test was performed, a seismic performance comparison was performed according to the presence or absence of a seismic isolation device. The attenuation effect of the seismic isolation device are analyzed by comparing response acceleration and displacement for different frequencies and acceleration levels. Result: As a result of the test, the acceleration amplification was up to 42% less than when the seismic isolation device was installed in comparison to the other case without the seismic device. This is believed that the amplification energy has reduced because the displacement between the double slip friction surfaces of the seismic device play a role in dissipating the seismic energy. Conclusion: The seismic device with double slip friction surfaces has a greater earthquake attenuation effect in strong earthquakes than in weak ones, so the greater the frequency, the better the earthquake attenuation effect. Therefore, it is judged that earthquake energy can be decreased by applying to electric equipment such as distribution panels.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.107-115
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• 2014

In this study, we examined the seismic isolation effects due to the difference between the center of mass of the building and the center of stiffness of isolation layer. Because the base isolation technique is a technique that is highly dependent on the performance of seismic isolation devices installed on the seismic isolation layer, we have to examine the horizontal stiffness of seismic isolation devices after making them. If difference between the design stiffness and the actual stiffness of the seismic isolation device occurred, a big problem may be generated in the upper members on the seismic isolation layer. The analytical results show that the more eccentricity increases, the more maximum response acceleration, story shear and the member forces of the upper part of the structure increases, and the damage is expected to be in excess. Therefore, it is recommended that if possible, isolation devices have to be designed to coincide the center of mass of the building with the center of stiffness of isolation layer. If not after making isolation devices, they need to be relocated to prevent the eccentricity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.221-230
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• 2004

In this paper, the dynamic response of a multi-story steel moment resisting frame equipped with viscoelastic dampers or lead rubber bearing type isolators subjected to seismic loads is investigated analytically. The objective of this study is to find the best location of viscoelastic dampers by the maximum stress method and maximum story drifts method from structure analysis. Also, a secondary objective of the study is to compare the member force, combined stress, and natural period of the structure retrofitted with viscoelastic dampers or lead rubber bearing type isolators to find effective vibration control method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.116-121
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• 1994

지금까지 대형 구조물에 널리 사용되고 있는 Base Isolator는 특히, 지진하중에 대하여 상부 구조물의 지반분리(base isolation)을 이용한 지진제어를 목적으로 하기 때문에 Seismic Isolator라 한다. 일반적으로 면진베어링에는 LRB(Laminated Rubber Bearing) 방식과 R-FBI(resilient-friction base isolator) 방식으로 크게 나눌 수 있다. LRB 방식은 가장 널리 사용되는 면진베어링으로써 방진고무를 주된 재료로 하고 수직강성을 보강하기 위하여 steel plate를 조합하여 제작하며, 초기강성 및 에너지 소산능력을 증가시키기 위하여 단면중앙에 납(lead plug)를 삽입하기도 한다. R-FBI 방식은 방진고무 적층판 내부에 미끄럼판을 가지고 있으므로 LRB 방식에 비하여 더 큰 수평변위를 발생시킬 수 있다. 이번에 설계 제작한 면진베어링은 LNG 저장탱크의 Seismic Isolation을 목적으로 적용대상의 사양에 맞추어 설계 제작하고 성능평가 시험을 수행하여 LNG 저장탱크, 원자로, 대형 건축물등 지진으로부터 보호되어야 하는 대형구조물의 방진재로 적용할 수 있는가를 평가하고자 한다. 본 논문에서는 제작된 면진베어링의 설계를 검증하고 방진고무(HDR)재료의 물리적 특성시험, 축소모델에 의한 정적, 동적시험을 통하여 시험방법을 소개하고 이러한 시험결과를 기초로 하여 면진베어리의 성능을 평가하였으며, 면진베어링의 온도변화, 외부 수직하중의 변화등에 따른 특성변화와 LNG 저장탱크와 면진베어링의 체결방법에 따른 시험으로 체결방법을 검증하였으며, 대상물의 사양에 적합한가를 고찰하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.385-392
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• 2014

The isolators have been generally used to reduce a seismic force. If the isolators apply to the nuclear power plants(NPPs), the durability and capacity for the structures and equipments should be ensured during the life time. In this study, the long-term behavior of isolated NPPs was analyzed for ensuring the seismic safety. The properties of isolator due to the age-related degradation were analyzed. And the seismic behavior of isolated buildings was analyzed by considering the aging of rubber bearings in different temperature environments. According to the analysis results, the natural frequency of structures was increased with time. But the maximum acceleration and maximum displacement of isolated structures have not changed significantly. Although the damaged of structure did not occurred by aging of isolators, it was presented that the spectral acceleration at the target frequency of isolated structure increased with the temperature. Therefore the isolators in the isolated buildings should be carefully designed and manufactured considering the temperature-dependancy of rubber material.

• Journal of Korean Association for Spatial Structures
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• v.10 no.3
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• pp.49-56
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• 2010

In this study, the control performance of a smart top-story isolation system for tall buildings subjected to wind excitation was investigated. To this end, a 77-story tall building structure was employed and wind loads obtained from wind tunnel test were used for numerical simulations. The top-story of an example structure is separated from the main structure by a smart base isolation system composed of friction pendulum systems (FPS) and MR dampers. The primary purpose of the smart top-story isolation system is to mitigate the dynamic responses of the main structure, but the excessive movement of the isolated top story may cause the unstableness of the building structure. Therefore, the skyhook control algorithm was used to effectively reduce both responses of the isolated top story and the main structure. The control performance of the proposed smart top-story isolation system was investigated in comparison with that of the passive top-story isolation system. It has been shown from numerical simulation results that the smart top-story isolation system can effectively reduce wind-induced responses of the example building structure compared to the passive top-story isolation system with reduction of the top-story movement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.52-58
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• 2016

Recently, interest in structural stability has increased due to earthquakes. Isolation systems can improve seismic ability without harming the functions and appearance of existing and new constructions, and they have established efficiency in foreign country that have experienced earthquakes. In this study, an isolation system is suggested using a natural rubber bearing (NRB) on a stainless water tank for stability assurance in an earthquake. A shaking table test was carried out to evaluate the seismic capacity of a non-isolated water tank and an isolated tank. Displacement meters in the water tank measured the behavior characteristics of the tanks, which were compared using artificial seismic waves of 0.154 g, 0.231 g, 0.341 g, and 0.348 g with water levels of 0.0 m, 1.5 m, and 2.5 m. At 2.5 m, a decrement effect was generally shown in the isolated water tank, and a bigger displacement occurred in the non-isolated water tank than in the isolated one at water levels of 0.0 m and 1.5 m. It is interpreted that the weight of different water levels affects the decrement effect. If seismic reinforcement is done, the isolated bearing should be designed while considering the fluid storage level.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.377-388
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• 2016

This study is aimed to evaluate the embedment effect of foundation as compared to the surface foundation on the response of a base-isolated nuclear power plant structure. For this purpose, the boundary reaction method (BRM), which is a two-step frequency domain and time domain technique, is used for the nonlinear SSI analysis considering nonlinear behavior of base isolators. The numerical model of the BRM is verified by comparing the numerical results obtained by the BRM and the conventional frequency-domain SSI analysis for an equivalent linear SSI system. Finally, the displacement response of the base isolation and the horizontal response of the structure obtained by the nonlinear SSI analysis using the moat foundation model are compared with those using the surface foundation model. The comparison showed that the displacement response of the base isolation can be reduced by considering the embedment effect of foundation.