• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.602-605
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• 2011

본 논문에서는 마찰감쇠기가 설치된 건물이 붕괴하중을 받을 때의 에너지소산능력을 고려하여 등가감쇠비를 유도하였다. 마찰감쇠기는 주로 지진과 같은 수평하중에 대한 에너지를 소산하기위해 설치된다. 마찰감쇠기를 대각 가새형으로 설치하면 수평하중에 대한 저항력뿐 만아니라 수직하중에 대한 저항성능도 발휘된다. 건물에 설치된 마찰감쇠기는 외력의 크기에 따라 정지와 운동의 상태를 반복하여 외부 입력에너지를 소산시키기 때문에 외력과 응답관계가 비선형이다. 건물은 고유의 점성감쇠를 가지므로 마찰감쇠기가 설치된 건물은 마찰과 점성감쇠를 동시에 고려해야하므로 해석적인 정해를 구하기가 어렵다. 에너지 평형을 이용하여 등가감쇠비를 구하고 운동방정식을 등가선형화하면 쉽게 저항 성능을 파악할 수 있다. 우선 건물에 영향을 미치는 것은 감쇠이므로 감쇠의 영향력을 마찰력비, ${\gamma}_c$로 나타내었다. 둘째, 정해를 마찰력비로 표현하여 유도하고 응답특성을 파악하였다. 셋째, 에너지 균형식을 통해 등가감쇠비를 산정하였다. 마지막으로 등가감쇠비를 검증하기 위하여 등가감쇠비를 이용하여 등가선형화한 응답과 실제 마찰감쇠기를 설치하여 비선형 수치해석한 결과와 비교, 검증하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.449-453
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• 2010

본 논문에서는 점성 및 감쇠가 있는 단자유도 구조물의 등가감쇠비를 효율적으로 구하는 방법을 제시하였다. 건물에 설치된 마찰감쇠기는 외력의 크기에 따라 정지와 운동의 상태를 반복하여 외부 입력에너지를 소산시키기 때문에 외력과 응답관계가 비선형이다. 마찰감쇠기가 설치된 단자유도 건물은 마찰감쇠기외에 점성감쇠가 동시에 존재하므로 해석적인 정해를 구하기가 어렵다. 등가감쇠비를 산정하기 위해서 첫째, 점성과 마찰감쇠가 있는 단자유도계 건물의 자유진동 정해를 통하여 변위응답과 가속도 응답특성을 분석하였다. 둘째, 자유진동의 경우 응답이 멈출 때까지 소산에너지식을 이용하여 등가점성감쇠비를 구하였다. 셋째, 조화가진 일 때는 수치해석을 통하여 마찰력비 $F_r$에 따른 응답 특성을 알아보았다. 넷째, 조화가진의 경우 에너지 균형식을 바탕으로 등가점성감쇠비를 유도하였다. 등가점성감쇠비는 변위응답비의 영향을 받으므로 응답을 알아야만 구할 수 있다. 건물 응답의 진동수 특성은 협소영역(narrow band)이므로 고유진동수에 의해 지배된다고 가정하여 등가점성감쇠비를 구하였다. 마지막으로, 유도한 자유진동과 조화가진의 등 가점성감쇠비를 이용한 등가선형운동방정식의 해를 비선형 수치해석 한 결과와 비교하여 검증하였다.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.115-121
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• 2006

In recent years vibration control damper made of low yield point steel is expected to play an important role in controlling structural vibration induced earthquake and wind. But their dynamic characteristics and energy dissipation effects on the whole structure model are not clarified. In this paper, firstly, we presents the results of cyclic tests on low yield steel dampers. Secondly, forced vibration tests on existence three stories steel structure model with low yield point steel dampers are presented. Lastly, it is estimated energy amount which is dissipated through the hysteresis dampers by using two types of analytical models, hysteresis model and equivalent linear model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.199-208
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• 2010

A friction damper installed at a building shows nonlinear behavior since its stick and slip states are occurred repeatedly depending on the amplitude of external loadings to dissipate input energy. Friction damping is existed for the building with a friction damper. In additionally viscous one is inherently included. Therefore, the building installed in such combined damping is quite involved to find the analytical solution. In this study, first, displacement and acceleration characteristics are identified based on the exact solution for a single-degree-freedom building with a friction damper having both friction and viscous damping. Second, in free vibration, the equivalent viscous damping ratio is obtained by the energy dissipation. Third, numerical analysis is carried out to find response configuration with various friction force ratios. Fourth, corresponding equivalent viscous damping ratio is derived with the finding that the response reaches into steady-state for both friction and viscous damped structure. It is deduced using balance of input external energy and output dissipation energy for steady-state response. Finally, the equivalent viscous damping ratios of free or harmonic vibration are verified through nonlinear analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.435-443
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• 2010

This study presents key parameters for the structure installed with MR controller in reducing its responses. MR controller is regarded as Bingham model of which control forces are frictional and viscous ones. The parameters are identified as friction force ratios, $R_f$ and $R_h$ which are, respectively, ratio of MR controller friction force to static restoring force for free vibration and ratio of the friction force to amplitude of harmonic force. Structure-MR controller system shows nonlinear response behavior due to friction force. Energy balance strategy is adopted to transform the behavior to linear one with equivalent damping ratio. Finally, proposed equivalent linear process is compared to the nonlinear one, which turns out to give acceptably good results.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.31-38
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• 2008

A column test was performed far a new-type column with a quasi static test. An internally confined hollow reinforced concrete column with a corrugated steel tube (ICH RC-CT column) was tested to evaluate its seismic performance. And also, a general solid RC column was tested fur the comparison. The test was performed as planned drift levels. The lateral displacements and the lateral loads of column specimens were measured during tests. From the test results, the ICH RC-CT column showed smaller energy absorbing capacity than a solid RC column but showed the almost equal energy ductility and equivalent viscous damping ratio to those of the solid RC column.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.46-51
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• 2008

The damping of a shock absorption device composed of nonlinear disk spring stacks and rubber rings was investigated. Friction forces of rubber rings and hysteresis of disk springs were obtained experimentally. The hysteresis curves of several types of disk spring stacks were approximated, from which the energy dissipated was estimated. Based upon the friction force and the energy dissipated, 4 damping models were presented and shock responses of the damping models were investigated. The hysteresis of disk spring is more meaningful than the friction of the rubber ring for the damping. For practical use, equivalent viscous damping model for total energy dissipated per cycle was suggested.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.215-226
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• 2008

A column test was performed for a hollow composite column to evaluate its seismic performance. The seismic performances of a hollow composite column and a reinforced concrete (RC) column were evaluated and compared by quasi-static tests. Lateral displacements and lateral loads of the column specimens were measured during tests. Ductilities, absorbed energy, equivalent damping ratios, and damage indices were calculated from the recorded data. From the test results, the hollow composite column showed a seismic performance superior to the column in terms of double moment capacity, ultimate energy, and energy absorption.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.53-65
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• 2007

Column tests were performed for a new type of column, the internally confined hollow concrete filled tube column (ICH CFT column), to evaluate its seismic performance. The seismic performances for two types of ICH CFT columns and a general solid RC column were evaluated and compared by quasi-static tests. The displacements and the lateral loads of column specimens were measured during tests. Ductilities, absorbed energy, equivalent damping ratios, damage indices were calculated from recorded data. From the test results, the ICH CFT column shows superior seismic performances with double moment capacity and larger energy absorbing capacity over that of a solid RC column.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.47-55
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• 2003

This study proposed a convenient seismic design procedure for buckling-restrained braced frames based on the equivalent energy concept. The design process begins with the computation of input energy from response spectrum. Then the elastic energy and plastic energy are computed based on the equal energy concept. The computed plastic energy is distributed to each story along energy distribution ratio and the cross-sectional area of each brace is computed so that all the plastic energy is dissipated by the brace. The proposed procedure was applied to the design of three-, six-, and twenty-story steel frames with buckling-restrained braces, and artificial earthquake records were used for verification of the proposed method. According to analysis results, top story displacements of the low-rise structure satisfies the given target displacement however that of the twenty-story structure was much smaller than the given target displacement.