• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.173-181
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• 2006

Many isolated bridges are designed and constructed after the introduction of the seismic design. However those bridges designed in engineering fields have unnecessarily high serviceability limit and brittle failure mechanism, which do not satisfy the seismic design concept. Such design results are due to the excessive substructure stiffness of the conventional design method as well as the misunderstanding of the seismic design method. In this study an isolated bridge designed with the conventional design method is selected and the same bridge with steel bearings is modelled for the comparative seismic design. From the comparison, the seismic design procedures satisfying the required performance levels are provided for the two bridges. It is confirmed that the isolated bridge requires more complicated design procedure with trial and error methods and reanalyses but provides higher serviceability limit compared to the bridge with steel bearings. However, because the required serviceability limit can also be obtained by adjusting substructure stiffness, it is a resonable seismic design process that an isolated bridge is to be considered as an alternative design when the ductile failure mechanism is not obtained with a bridge with steel bearings.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.9-17
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• 2004

The seismic performance evaluation and retrofit process are very important in old existing bridges. If the result is not appropriate. then a retrofit process are required. Among various retrofit methods, the seismic isolation is a very useful method. because it can be applied by replacing old bridge bearings. In this study, the effectiveness of seismic isolation is rationally verified. For this purpose, two seismic isolations used widely are selected and non-linear static and dynamic analyses are performed. The responses of existing bridges are compared with those of retrofited bridges by seismic isolation bridge for earthquake of target level. and seismic performances are evaluated.

• Computational Structural Engineering
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• v.11 no.1
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• pp.38-45
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• 1998

최근 국내외에서 활발히 개발되고 있는 지진격리 시스템은 원자력 발전소, 교량, 중요한 공공건물 등의 지진피해를 최소화하기 이하여 널리 적용되고 있다. 그리고 다른 방법에 비하여 경제성 및 효율성이 우수하기 때문에 관련 연구 및 응용이 활발히 진행되고 있다. 이에 따라 국내외에서 격리시스템의 비선형성과 구조물의 불연속성을 고려한 지진격리 구조물의 해석을 통한 거동을 규명하는 연구가 과거 수년간 활발히 진행되어 왔다. 당사(금호건설)는 상부하중 지지능력과 감쇠능력이 우수한 지진격리장치를 개발하였으며 지진격리장치를 설치한 교량의 지진해석을 수행하여 본 지진격리 시스템의 이론적 성능을 파악하였다. 본 수치해석은 CrayC94에 탑재된 비선형 해석에 뛰어난 것으로 알려진 ABAQU를 이용하였다. 본 지진격리 시스템은 적층고무받침(Laminated Rubber Bearing)과 PTFE 미끄럼받침으로 구성되어 있으며, 적층고무받침은 주로 복원력을 제공하며 PTFE 미끄럼받침은 상부하중을 지지하며 마찰감쇠를 제공하여 에너지를 소산하는 역할을 한다. 본 수치해석에서는 선형스프링과 마찰요소를 이용하여 각각을 모형화하였다. 개발된 지진격리 시스템이 주로 사용될 상판자중이 무거운 다경간 연속 PC Box Girder교를 모델교량으로 선택하여 해석을 수행하였으며 수치해석에 사용된 격리시스템의 사전에 수행된 동특성 실험결과를 활용하였다. 이러한 해석을 통하여 이론적 효율성을 파악할 수 있었다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.223-228
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• 2000

지진격리교량은 강진지역의 지반운동과 구조물의 거동에 근거한 내진설계 개념을 바탕으로 설계되었다. 그러나 지반운동의 특성과 구조물의 거동에 있어서 한반도와 같은 중약진 지역과 지각변동운동이 활발한 강진지역은 큰 차이를 보이고 있다. 따라서 중약진 지역의 내진설계에서는 지반운동의 특성이 반영되어야 할 필요가 있으며, 특히, 지진격리교량의 경우에는 교각의 연성 등 중약진 지역의 구조물의 거동특성이 반영되어야 한다. (중략)

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.442-448
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• 2003

최근 장대교량의 건설이 증가하고 지진에 대한 관심이 고조되면서 교략의 내진설계와 면진설계가 교량설계의 주요항목으로 자리잡게 되었다. 특히 최근 ILM교량과 같은 다경간 장대교의 경우 지진시 교량의 상부구조와 하부구조를 격리시켜 주기를 변화시키는 LRB를 이용한 면진설계가 주로 이루어지고 있다. 그러나 아직까지 국내에는 Mt5의 거동과 기본성능에 대한 실험데이터가 절대적으로 부족하며, 따라서 그 특성을 엄밀히 검증하지 못한 채 고속도로 및 국도상의 교량에 LRB를 다수 사용하고 있는 현실이다. 본 연구에서는 실교량에 사용될 LRB에 대하여 기본성능 중의 하나인 피로마모시험을 수행함으로써 온도하중과 같은 반복하중에 대한 LRB의 피로거동을 모사하고 피로시험 전.후의 기본성능의 변화를 파악하였다. 이러한 LRB의 기본성능에 대한 실험온 LRB의 성능에 대한 검증과 함께 LRB의 거동에 대한 불확실성을 줄일 수 있는 기본 자료로 축적할 수 있으며, 현재 한국도로공사 도로교통기술원에서 마련중인 지진격리장치(LRB) 성능시험기준(안)의 정립에 기초 자료로참고하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.139-146
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• 2004

In this paper, the seismic analysis and the modeling techniques have been introduced for seismic performances assessment, when seismic isolation bearings are applied to a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. El Centro earthquake(1940, N00W) used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.21-27
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• 2007

In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they Just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and lead rubber bearings far the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.

• 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 Computational Structural Engineering Institute of Korea
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• v.21 no.2
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• pp.145-151
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• 2008

The research so far has primarily analyzed efficiency improvement but in this research, it analyzes the characteristics of earthquake behavior, with changed pier heights, through ordinary and seismic analysis. For this, the kind of bridge bearing has been changed against PSC I-shaped bridge, which is mostly used in practice, and at all times earthquake analysis has been performed with through height of pier. Especially considering sectional power resulting from earthquake analysis, displacement of PSC I-shaped bridge bearing, diameter of pier pillar by earthquake load, and upper spare gap have been analyzed. In case of high-pear, seismic isolated device is decided as proper for cars' driving and for management of bridge since it decreases movement of upper structure, than elastic bearing, reducing size of elastic connect device, and it's been analyzed it is effective for improvement of fine view and economic efficiency reducing section of lower bridge structure. Finally, when design PSC I-shaped bridge bearing, for the proper structure and high-pier side, applying seismic isolated device through precise inner analysis is proper than applying equal elastic bearing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.105-108
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• 2008

For the early seismic isolation design in Korea, foreign products of isolation bearings were used. But these days, the application of domestic products of isolation bearings is increasing. However various experimental studies can be found very seldom on the extreme and lonr term behaviors of isolation bearings. In this study, we considered the laminated rubber type isolation bearings that have many application cases in Korea and we evaluated their shear strength, long term characteristics such as aging and creep affecting shear strength of bearings in long term period. For the reality of experiments, fabricated isolation bearing specimens are designed for a real structure and shear loading was applied under design compressive loads. To evaluated aging effect, the specimens were exposed to high temperature environment for certain period and their shear properties were measured to compare with their original values. Also we measured creep amount of isolation bearings under constant compressive load for 1,000 hours and estimated creep amount after 60 years compatible with general life cycle of bridges.