• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.1
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• pp.31-36
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• 2001

본 논문에서는 지점근처에 납-전단 댐퍼(LSD)가 설치된 케이블의 동적 거동에 대해 다루었다. 이러한 동적 거동에 대한 파악은 케이블의 진동 감소 목적으로 댐퍼를 설계하는 경우 중요한 절차중 하나이다. 납-전단 댐퍼와 같은 이력형 댐퍼의 실제 이력곡선에 기초하여 본 연구에서는 납-전단 댐퍼의 이력곡선을 완전 탄소성으로 가정하였다. 납-전단 댐퍼의 역학적 모델은 등가 켈빈 모델을 사용하였으며 케이블의 새그 효과를 고려하였다. 납- 전단 댐퍼의 용량이라고 할 수 있는 항복력을 설계변수로 선택하고 케이블에 최적의 감쇠효과를 부여하는 동적학적 관계에 대해 연구하였다. 또한 댐퍼가 케이블에 설치되는 지점과 케이블의 장력에 대한 댐퍼의 감쇠효과에 대해서도 연구하였다. 매개변수 해석결과 케이블의 기하학적 형상 및 댐퍼의 설치조건에 따라 납-전단 댐퍼가 케이블에 부가하는 감쇠의 크기가 변함을 알 수 있었으며, 이때 최대의 감쇠성능을 발휘하는 최적 항복력이 존재하는 것을 알았다.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.223-229
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• 2016

This study proposes a new technology for a smart damper with flag-shaped behavior using the combination of magnetic friction and rubber springs. The magnet provides friction and, thus, energy dissipation, and the rubber springs with precompression contribute to present self-centering capacity of the damper. To verify their performance, this study conducts dynamic tests of magnet frictional dampers and precompressed rubber springs. For the purpose, hexahedron Neodymium (NdFeB) magnets and polyurethane rubber cylinders are used. In the dynamic tests, loading frequency varies from 0.1 to 2.0 Hz. The magnets provide almost perfect rectangular behavior in force-deformation curve. The rubber springs are tested without or with precompression. The rubber springs show larger rigid force with increasing precompression. Lastly, this study discusses combination of rigid-elastic behavior and friction to generate 'flag-shaped' behavior for a smart damper and suggests how to combine the magnets and the rubber springs to obtain the flag-shaped behavior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.82-88
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• 2010

The purpose of this research is a seismic capacity evaluation and strengthening of existing railway station buildings, which were constructed before the seismic design code activated. The seismic capacity of 2nd story RC station building is evaluated by using nonlinear time-history analysis. Analysis results are checked by story drift ratio and story shear, which are described in design code. As a result, the story shears are exceeding the base shear of the design code, the appropriate seismic strengthening methods are needed. To improve the seismic capacity, metallic dampers are used. Evaluation parameters are metallic damper shape and damper installation methods. Dampers are installed in four places in X and Y directions of station buildings. By reviewing of time-history analysis results, the metallic damper, which is installed inverted K-brace type, shows a better seismic performance than other damper shape and installation methods.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.119-127
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• 2011

The purpose of this study is to propose damper system which is easy to design, which can ensure against risks, and to verify earthquake response characteristics. For this study, the pseudo dynamic earthquake response tests carried out for steel frames with metallic damper. As a result, in case of using the metallic damper as a vibration control device proposed by this study, the damper having higher stiffness than main-structure turned to the state of plasticity by little displacement has been proved to be able to absorb earthquake energy.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.457-464
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• 2003

최근 교량의 건설에 있어서 내진설계가 주요문제로 부각되면서, 구조물의 진동응답을 제어 하는 갖가지 형태의 진동제어 기법이 적용되고 있다. LRB(Lead Rebbe. Bearing), LUD(Lock Up Device)등 다양한 지진격리장치가 설계에 적용되고 있으며 특히, 설계변경 .내진보수보강과 같이 제약 조건이 있는 상황에서 유용한 면진방법으로 사용되고 있다. 이러한 지진격리장치는 기본적인 설계특성인 수평강성, 감쇠성능에 대한 검증을 필요로 한다. 특히, 지진과 같은 동적하중에 대하여 하중속도, 수직력, 변형률 등에 대한 의존성과 내구성의 검토가 필요하며 유사장치에 대하여 검증실험기준의 정립이 진행 중에 있다. 강재이력댐퍼인 E-Shape 댐퍼는 지진격리장치로서 교각의 고정단에 교좌장치로 설치되어 상시에는 탄성영역 내에서 거동하는 고정단의 역할을 하다가, 지진발생시에는 E-Shape형태의 강재댐퍼가 소성변형을 통한 이력거동으로 에너지 소산기능을 가진 교좌장치이다. 최근 LRB에 대하여는 다양한 특성실험이 수행되고 있으나 상대적으로 강재이력댐퍼에 대하여는 이러한 검증실험이 수반되지 않고 사용되고 있다. 본 실험연구에서는 E-Shape 강재이력댐퍼에 대하여 연직하중, 수평변형률, 수평속도에 패한 동적특성을 평가함으로서 강재이력댐퍼를 이용한 지진격리설계의 타당성과 면진성능을 평가해 보았다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.139-145
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• 2018

An outrigger system is used widely to increase the lateral stiffness of high-rise buildings, resulting in reduced dynamic responses to seismic or wind loads. Because the dynamic characteristics of earthquake or wind loads are quite different, a smart vibration control system associated with an outrigger system can be used effectively for both seismic and wind excitation. In this study, an adaptive smart structural control system based on an outrigger damper system was investigated for the response reduction of multi-hazards, including seismic and wind loads. A MR damper was employed to develop the smart outrigger damper system. Three cities in the U.S., L.A., Charleston, and Anchorage, were used to generate multi-hazard earthquake and wind loads. Parametric studies on the MR damper capacity were performed to investigate the optimal design of the smart outrigger damper system. A smart control algorithm was developed using a fuzzy controller optimized by a genetic algorithm. The analytical results showed that an adaptive smart structural control system based on an outrigger damper system can provide good control performance for multi-hazards of earthquake and wind loads.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.685-690
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• 2008

Recently, as large structures become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a means to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, a base isolation system using hysteretic damper is shown to effectively protect structures against earthquakes. A mechanical model is determined that can effectively portray the behavior of a typical E-shape device. Comparison with experimental results for a hysteretic damper indicates that the model is accurate over a wide range of operating conditions and adequate for analysis. The seismic performance of hysteretic dampers are studied and compared with the conventional systems as a base isolation system. A five-story building is modeled and the seismic performance of the systems subjected to three different earthquake is compared. The results show that the hysteretic damper system can provide superior protection than the other systems for a wide range of ground motions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.135-142
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• 2020

In the case of a concrete structure, vibration problems occur under various conditions because of its low damping performance. To solve this problem, a study on the high damping performance of the polymer concrete with hybrid damper has recently been increased. Since water is not used in polymer concrete, the curing time is short. Also, the physical properties and dynamic properties of polymer concrete are quite excellent. So polymer concrete is widely expected to be used for structural materials. The hybrid damper is the structural system that consists of steel balls and viscous fluid inside the pipe which is embedded in polymer concrete. It can reduce the structural vibrations through the energy dissipation mechanism of viscous fluid and steel balls. In this study, the physical and dynamic properties of polymer concrete with hybrid damper were compared with ordinary concrete. As a result, the elasticity coefficient and the strength of the polymer concrete with hybrid damper were so much excellent. In particular, the tensile strength was 6.5 to 10 times higher than ordinary concrete. The frequency response function and damping ratio were also compared. As a result, the dynamic Stiffness of the polymer concrete was 25% greater than that of ordinary concrete. The damping ratio of the polymer concrete was approximately 3 times higher than that of ordinary concrete. Although the dynamic stiffness of the hybrid damper showed similar tendency, the damping ratio was 3.5 times higher than that of ordinary concrete. Therefore, the polymer concrete with hybrid damper was superior to ordinary concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.36-41
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• 2016

In this study, numerical analyses were used to investigate the performance of a coupling control method for the dynamic responses of adjacent buildings under multiple hazards. Numerical simulations were done using the earthquake loads of regions with strong seismicity in Los Angeles, California, and the wind loads in regions with strong winds in Charleston, North Carolina. The artificial earthquake and wind loads were made using SIMQKE and Kaimal Spectrum based on ASCE 7-10. Ten-story and twenty-story adjacent buildings were selected as example structures, and nonlinear hysteretic dampers were used to connect them. The Bouc-Wen model was used to model the nonlinear hysteretic dampers. The results show that the proposed control method could effectively reduce the dynamic responses, and the optimal control designs were different for each hazard.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.7
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• pp.659-666
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• 2009

This paper proposes a new method for dynamic modeling of electrorheological(ER) damper considering fluid compressibility. After describing configuration and operating principle of the ER damper, a quasi-static modeling of the ER damper is conducted on the basis of Bingham model of ER fluid. Subsequently, the dynamic model for describing the ER damper considering compressibility of ER fluid and gas chamber is obtained using the lumped parameter method. This method includes dynamic motions of annular duct, upper chamber, lower chamber and connecting pipe. The hysteresis behavior of the ER damper is evaluated through computer simulations and compared with experimental results. In addition, the hysteresis behavior due to the compressibility of ER fluid and gas chamber is investigated through computer simulations.