• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.473-480
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• 2003

In these days, The base isolation system is often used improve the seismic capacity of the structure Instead of conventional techniques of strengthening the structural members. The purpose of this study is to evaluate dynamic property evaluation of control equipment using Lead Rubber Bearing. In this study, analysis numerical was performed to determine the optimal dynamic property of lead rubber bearing and damper which minimize the response of base from in main control room. Also the analytical results was composed with the test results peformed in previous study

• 대한토목학회논문집
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• 제13권5호
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• pp.13-18
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• 1993

본 논문의 목적은 LRB 기초분리장치가 설치된 교량의 내진효과를 해석하는 것이다. 기초분리방법은 지진력이 구조물에 전달되기 전에 그 영향을 최소화시키는 방법으로 현재 건물, 발전소, 교량 등의 구조물에 실용화되고 있다. 본 연구에서는 대표적인 기초분리장치인 Lead Rubber Bearing이 설치된 교량의 단순화된 모델을 개발하고 여러 크기의 LRB에 대하여 지진의 영향을 해석하였다. 단순화된 교량모델의 운동방정식을 Newmark ${\beta}$ 방법에 의해 시간이력해석을 수행하였다. 기초분리장치의 모델로는 이중선형성을 갖는 스프링을, 교각모델로는 비선형성 및 강성저하를 고려한 Q-HYST모델을 사용하였다. 해석예로 미국 네바다주에 소재한 Rose Creek 교량에 대한 남북방향 El Centro지진(1940)의 영향을 해석하였다. 상부구조 횡방향처짐, 교각연성 및 교각 밑면 전단력을 구하였다.

• Earthquakes and Structures
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• 제5권1호
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• pp.23-48
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• 2013

In this study, the effect of flexibility of superstructures and nonlinear characteristics of LRB (Lead Rubber Bearing) isolator on inelastic response of base isolated structures is investigated. To demonstrate the intensity of damage in superstructures, demand response modification factor without the consideration of damping reduction factor, demand RI, is used and the N2 method is applied to compute this factor. To evaluate the influence of superstructure flexibility on inelastic response of base isolated structures, different steel intermediate moment resisting frames with different heights have been investigated. In lead rubber bearing, the rubber provides flexibility and the lead is the source of damping; variations of aforementioned characteristics are also investigated on inelastic response of superstructures. It is observed that an increase in height of superstructure leads to higher value of demand RI till 4-story frame but afterward this factor remains constant; in other words, an increase in height until 4-story frame causes more damage in the superstructure but after that superstructure's damage is equal to the 4-story frame's. The results demonstrate that the low value of second stiffness (rubber stiffness in LRBs) tends to show a significant decrease in demand RI. Increase in value of characteristic strength (yield strength of the lead in LRBs) leads to decrease in the demand RI.

• 대한토목학회논문집
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• 제32권2A호
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• pp.109-116
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• 2012

지진격리장치로서 납고무받침의 동적 특성은 주재료인 고무재료의 동적거동과 비선형 성질에 의존하고 있다. 역학적이나 환경적인 영향으로 인해 고무재료에 노화가 진행되고 결국에는 손상이 불가피하게 발생하게 된다. 고무재료의 노화의 주원인은 높은 온도에서 반응열로 인한 산화반응으로 알려져다. 이에 따라 납고무받침의 가속 열 노화실험을 수행하여 열 노화 전 후에 대해 받침의 특성값을 상호 비교하였다. 실험 결과 열 노화 현상은 전단강성과 에너지 감쇠 그리고 등가감소계수에 영향이 있음을 알 수 있었다. 또한 열 노화에 의한 동적특성의 저하를 실제 교량에 적용하여 납고무받침의 열 노화가 교량의 교각의 내진성능에 미치는 영향을 수치해석을 통해 비교분석하였다. 해석결과 납고무받침에 대하여 열 노화에 따른 기본 특성변화가 교량의 내진성능에 미치는 영향은 크지 않음을 알 수 있었다.

• 한국지진공학회논문집
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• 제21권2호
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• pp.95-103
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• 2017

In order to modeling seismic isolation system such as lead-rubber bearing (LRB), bilinear model is widely used by many researchers. In general, an actual force-displacement relationship for LRB has a smooth hysteretic shape. So, Bouc-Wen model with smooth hysteretic shape represents more accurately actual hysteretic shape than bilinear model. In this study, seismic responses for seismically isolated nuclear power plant (NPP) with LRB modelled by Bouc-Wen and bilinear models are compared with those of NPP without seismic isolation system. To evaluate effect of earthquake characteristics for seismic responses of NPP isolated by LRB, 5 different site class earthquakes distinguished by Geomatrix 3rd Letter Site Classification and artificially generated earthquakes corresponding to standard design spectrum by Reg. Guide 1.60 are used as input earthquakes. From the seismic response results of seismically isolated NPP, it can be observed that maximum displacements of seismic isolation modelled by Bouc-Wen model are larger than those by bilinear model. Seismic responses of NPP with LRB is significantly reduced than those without LRB. This reduction effect for seismic responses of NPP subjected to Site A (rock) earthquakes is larger than that to Site E (soft soil) earthquakes.

• 한국구조물진단유지관리공학회 논문집
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• 제8권2호
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• pp.221-230
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• 2004

본 논문에서는 지진하중 작용시, 점탄성 감쇠기 및 면진장치를 설치한 다층 철골 모멘트 저항 골조의 동적응답을 해석적으로 규명하였다. 본 연구의 목적은 구조해석을 수행하여 최대 층간변위 및 최대응력법에 의해 효율적인 점탄성 감쇠기의 위치를 결정하는 것이다. 또한, 효율적인 진동 제어방법을 모색하기 위하여 점탄성 감쇠기 및 납삽입고무베어링형 면진장치에 의한 제어효과를 부재력, 조합응력, 그리고 구조물의 고유주기 등을 이용하여 상호 비교 분석하였다.

• 한국지진공학회논문집
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• 제19권5호
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• pp.207-217
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• 2015

In order to increase seismic performance of nuclear power plant (NPP) in strong seismic zone, lead-rubber bearing (LRB) can be applied to seismic isolation system of NPP structures. Simple equivalent linear model as structural analysis model of LRB is more widely used in initial design process of LRB than a bilinear model. Seismic responses for seismically isolated NPP containment structures subjected to earthquakes categorized into 5 different soil-site classes are calculated by both of the equivalent linear- and bilinear- LRB models and compared each others. It can be observed that the maximum displacements of LRB and shear forces of containment in the case of the equivalent linear LRB model are larger than those in the case of bilinear LRB model. From the seismic fragility curves of NPP containment structures isolated by LRB, it can be observed that seismic fragility in the case of equivalent linear LRB model are about 5~30 % larger than those in the case of bilinear LRB model.

• 한국지진공학회논문집
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• 제19권1호
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• pp.1-11
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• 2015

In order to perform a soil-isolation-structure interaction analysis of seismically isolated nuclear power plant (NPP) structures, the nonlinear behavior of a seismic isolation system may be converted to an equivalent linear model used in frequency domain analysis. Seismic responses for seismically isolated NPP containment structures subjected to a simple artificial acceleration history and different site class earthquakes are evaluated for the equivalent-linear and nonlinear models that have been applied to lead-rubber bearing (LRB) modeling. It can be observed that the maximum displacements of the equivalent linear model are larger than that of the nonlinear model. From the floor response spectrum analysis for the top of NPP containment structures, it can be observed that the spectral acceleration of an equivalent linear model at about 0.5 Hz frequency is about 2~3 times larger than that of a nonlinear model.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.43-50
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• 2005

도로교의 내진설계기준이 국내에 도입되어 적용된 것은 10여년에 불과하므로 아직 많은 교량에 내진성능 보강이 필요하다. 본 논문에서는 받침이 노후된 교량의 내진성능 보강방법으로서 적층고무받침으로 교체하는 방법의 타당성에 관하여 논하였다. 이를 위하여 내진상세가 없는 실물크기 RC교각 시험체를 제작하고 POT받침, 적층고무받침(RB), 납-적층고무받침(LRB)를 각각 설치하였다. 유사동적 실험을 통하여 이들 시험체의 지진시 거동을 모사하고 성능을 비교하였다. 실험결과로부터 제안된 내진보강기법의 타당성을 확인하였다.

• Computers and Concrete
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• 제21권5호
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• pp.495-504
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• 2018

The possibility of earthquakes in vulnerable regions indicates that efficient technique is required for seismic protection of buildings. During the recent decades, the concept is moving towards the insertion of base isolation on seismic prone buildings. So, investigation of structural behavior is a burning topic for buildings to be isolated in base level by bearing device. This study deals with the incorporation of base isolation system and focuses the changes of structural responses for different types of Lead Rubber Bearing (LRB) isolators. A number of sixteen model buildings have been simulated selecting twelve types of bearing systems as well as conventional fixed-base (FB) scheme. The superstructures of the high-rise buildings are represented by finite element assemblage adopting multi-degree of freedoms. Static and dynamic analyses are carried out for FB and base isolated (BI) buildings. The dynamic analysis in finite element package has been performed by the nonlinear time history analysis (THA) based on the site-specific seismic excitation and compared employing eminent earthquakes. The influence of the model type and the alteration in superstructure behavior of the isolated buildings have been duly assessed. The results of the 3D multistory structures show that the lateral forces, displacement, inertia and story accelerations of the superstructure of the seismic prone buildings are significantly reduced due to bearing insertion. The nonlinear dynamic analysis shows 12 to 40% lessening in base shear when LRB is incorporated leading to substantial allowance of horizontal displacement. It is revealed that the LRB isolators might be potential options to diminish the respective floor accelerations, inertia, displacements and base shear whatever the condition coincides. The isolators with lower force intercept but higher isolation period is found to be better for decreasing base shear, floor acceleration and inertia force leading to reduction of structural and non-structural damage. However, LRB with lower isolator period seems to be more effective in dropping displacement at bearing interface aimed at reducing horizontal shift of building structure.