• Structural Engineering and Mechanics
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• 제43권4호
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• pp.475-502
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• 2012

In this paper, the seismic analysis modeling technologies for sodium-cooled fast reactor (SFR) are presented with detailed descriptions for each structure, system and component (SSC) model. The complicated reactor system of pool type SFR, which is composed of the reactor vessel, internal structures, intermediate heat exchangers, primary pumps, core assemblies, and core support structures, is mathematically described with simple stick models which can represent fundamental frequencies of SSC. To do this, detailed finite element analyses were carried out to identify fundamental beam frequencies with consideration of fluid added mass effects caused by primary sodium coolant contained in the reactor vessel. The calculation of fluid added masses is performed by detailed finite element analyses using FAMD computer program and the results are discussed in terms of the ways to be considered in a seismic modeling. Based on the results of seismic time history analyses for both seismic isolation and non-isolation design, the functional requirements for relative deflections are discussed, and the design floor response spectra are proposed that can be used for subsystem seismic design.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.37-44
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• 2018

A base isolation system is widely used to reduce seismic responses of low-rise buildings. This system cannot be effectively applied to high-rise buildings because the initial stiffness of the high-rise building with the base isolation system maintains almost the same as the building without the base isolation system to set the yield shear force of the base isolation system larger than the design wind load. To solve this problem, the mid-story isolation system was proposed and applied to many buildings. The mid-story isolation system has two major objectives; first to reduce peak story drift and second to reduce peak drift of the isolation story. Usually, these two objectives are in conflict. In this study, a hybrid mid-story isolation system for a tall building is proposed. A MR (magnetorheological) damper was used to develop the hybrid mid-story isolation system. An existing building with mid-story isolation system, that is "Shiodome Sumitomo Building" a high rise building having a large atrium in the lower levels, was used for control performance evaluation of the hybrid mid-story isolation system. Fuzzy logic controller and genetic algorithm were used to develop the control algorithm for the hybrid mid-story isolation system. It can be seen from analytical results that the hybrid mid-story isolation system can provide better control performance than the ordinary mid-story isolation system and the design process developed in this study is useful for preliminary design of the hybrid mid-story isolation system for a tall building.

• 대한토목학회논문집
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• 제41권1호
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• pp.13-20
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• 2021

최근 우리나라는 주거 및 주차 공간의 확보를 위해 다양한 필로티 구조물이 건설되어 왔다. 하지만 이러한 필로티 구조물은 1층에 주차 공간을 확보하기 위해 벽체가 없는 돌출된 기둥의 형태로 건설되어 왔다. 이러한 형태는 지진 발생 시 일반적인 구조물에 비해 상대적으로 기둥의 파손이 쉽게 발생하며, 이러한 파손은 구조물의 붕괴로 이어질 수 있다. 따라서 본 연구에서는 MPS (Multi Performance System) 면진받침을 활용한 필로티 구조물의 안전성 확보에 대한 연구를 수행하였다. 기존에 건설되어 있는 필로티 구조물에 대해 MPS 면진받침 설치 유무에 따른 비선형 동적 해석을 수행하고 해석결과를 비교 및 분석하였다. 최종적으로 각각의 내진성능 평가를 수행하고 MPS 면진받침의 성능을 검증하였다.

• Earthquakes and Structures
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• 제7권6호
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• pp.1223-1240
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• 2014

Seismic isolation has been established as an effective earthquake-resistant design method and the lead rubber bearings (LRBs) are among the most commonly used seismic isolation systems. In the scientific literature, a sharp bilinear model is often used for capturing the hysteretic behaviour of the LRBs in the analysis of seismically isolated structures, although the actual behaviour of the LRBs can be more accurately represented utilizing smoothed plasticity, as captured by the Bouc-Wen model. Discrepancies between these two models are quantified in terms of the computed peak relative displacements at the isolation level, as well as the peak inter-storey deflections and the absolute top-floor accelerations, for the case of base-isolated buildings modelled as multi degree-of-freedom systems. Numerical simulations under pulse-like ground motions have been performed to assess the effect of non-linear parameters of the seismic isolation system and characteristics of both the superstructure and the earthquake excitation, on the accuracy of the computed peak structural responses. Through parametric analyses, this paper assesses potential inaccuracies of the computed peak seismic response when the sharp bilinear model is employed for modelling the LRBs instead of the more accurate and smoother Bouc-Wen model.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.417-423
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• 2006

The seismic characteristics with 3-Dimensional isolation systems have been studied using a shaking table system. In this study, we made nuclear power plant main control room floor systems and several seismic shaking table tests with and without isolation systems were conducted to evaluate floor isolation effectiveness. Isolation systems have showed large reduction effectiveness in acceleration and response spectra with x and z direction respectively, but horizontal isolation is more effective than vertical one It is required to make isolation systems of which design frequency is below 1Hz when applied to main control room of NPP, but considering much difficulties in making such isolation systems, it is recommended that much consideration should be taken into account when applied to main control room of NPP.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.424-431
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• 2000

After the Kobe earthquake(1995) in Japan, the Izmit earthquake(1997) in Turkey and the Chi-chi earthquake(1999) in Taiwan, the small-to-medium-sized earthquakes occurred in the Koreans peninsula and this shows the fact that Korea is not located in the safety zone of earthquake. The main concept of base isolation system is to reduce the member forces by decreasing the earthquake forces transmitted to superstructure instead of the conventional techniques of strengthening the structural members. This study investigates the effect of seismic response attenuation of computer floors using base isolation systems

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.383-390
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• 2002

The new seismic isolation system (StLRB) is developed, which can separate non-seismic displacements which come from the thermal expansion etc. in LRB design. The StLRB has 3 components, sliding system (PTFE + stainless plate), LRB (lead rubber bearing) and STU (shock transmit units). In this project, the StLRB is designed to apply to the bridge structure by analyzing the characteristics of each component and also the dynamic behavior of the structure was analyzed by non-linear analysis. The verification test was performed to show the two stages separated by STU units. Test results show the effectiveness of both the separation and the seismic isolation performance.

• 한국지진공학회논문집
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• 제2권3호
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• pp.51-60
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• 1998

Base isolation is an innovative design strategy that provides a practical alternative for the seismic design of structures. Base isolators, mainly employed to isolate large structures subjected to earthquake ground excitations and to rehabilitate structures damaged by past earthquakes, deflect and absorb the seismic energy horizontally transmitted to the structures. This study demonstrated that the base isolation system may offer effective performance for bridges during severe seismic events through shaking table tests. Two base isolation systems using laminated rubber bearings with and without hydraulic dampers are tested. The test results strongly show that the laminate rubber bearings cause the natural period of the bridge structure increased considerably, which results in the deck acceleration and the shear forces on the deck acceleratino and the shear forces on the piers reduced significantly. The results also demonstrate that the hydraulic dampers enhance the system's capacity in dissipating energy to reduce the relative displacement between the bridge deck and the pier.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.229-232
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• 1999

The seismic isolation technology has appeared to be increasingly necessary for highway brides LNG tank nuclear power plant and building structures in view of recent frequent earthquake vibrations in Korea. Also high-technology industries required effective seismic protection. The LRB(Lead Rubber Bearing) systen has been counted as the most effective way for seismic isolation which is now under development and widely used in industries. Hear the commercial FEM software for nonlinear analysis MARC has provided force-displacement curves on the rubber system. The analysis has been carried out about four cases ; 29.5mm and 59mm horizontal dislacements with/without a center hole. The unknown constants of the strain energy function of Ogden model have been obtained by a tension test,

• 국제초고층학회논문집
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• 제4권3호
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• pp.181-189
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• 2015

Shimizu Corporation Tokyo Headquarters, one of the city's leading office buildings, features many pioneering technologies that contribute to a sustainable society through environmental stewardship and a sophisticated disaster management facility. In terms of structural engineering, a seismic isolation system incorporating reinforced concrete core walls and precast concrete perimeter frames create a robust structure in the event of a large earthquake. In addition to the seismic resistance of the structure, several pioneering construction methods and materials are adopted. This office building can serve as a basis for new design and construction approaches and methodologies to ensure safe and economical structures.