• Title/Summary/Keyword: 등가감쇠비

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Design Parameter Identification Using Transfer Function of Liquid Column Vibration Absorber (LCVA) (전달함수를 이용한 LCVA의 설계변수 분석)

  • Lee, Sung-Kyung;Min, Kyung-Won;Chung, Hee-San
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.4
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    • pp.47-55
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    • 2009
  • The purpose of this study is to verify the transfer function of input acceleration and output control force by linearizing a velocity-dependent damping term of Liquid Column Vibration Absorber (LCVA). Analytical and experimental research is conducted to identify natural frequency, damping ratio and participated mass ratio of LCVA with various section ratios of vertical and horizontal areas. Findings obtained experimentally by the shaking table test are compared with analytical findings using optimization technique with constraints. The results indicate that the level of liquid and section ratio of LCVA affect the characteristics of damping ratio and mass ratio. Damping and mass ratio increase as the section of vertical column of LCVA decreases, due to turbulence in the elbow of LCVA.

Hysteretic Characteristics of Wooden Frames of Three-Bay-Straw-Roof House under Lateral Cyclic Load (수평 교번하중에 대한 초가삼간 목조 프레임의 이력특성 평가)

  • 서정문;최인길;전영선;이종림;신재철
    • Journal of the Earthquake Engineering Society of Korea
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    • v.1 no.3
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    • pp.21-27
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    • 1997
  • In this paper, the hysteretic characteristics of traditional wooden house frame,which is fabricated by Sagaemachum, under cyclic lateral load are presented. Full scale frame models are used in the tests. The skeleton curves of traditional wooden frame are quite different from those of wooden frames which are fabricated using nails or bracings. The equivalent viscous damping ratios of the frame system are about 27% and 13% for ordinary and high-column frames, respectively. The nonlinear hysteretic characteristics of the frame is modeled by the so called Modified Double Target model.

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Seismic Performance of Internally Confined Hollow RC Column with Corrugated Steel Tube (파형강관 내부 구속 중공 철근 콘크리트 기둥의 내진 성능)

  • Han, Taek-Hee;Kim, Jong-Min;Kang, Jun-Suk;Kang, Young-Jong
    • 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.

Optimization Design of Damping Devices for a Super-Tall Building Using Computational Platform (전산플랫폼을 이용한 초고층구조물의 감쇠장치 최적화 설계)

  • Joung, Bo-Ra;Lee, Sang-Hyun;Chung, Lan;Choi, Hyun-Chul
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.2
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    • pp.145-152
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    • 2015
  • In the study, the effects of damping devices on damping ratio increase and wind-load reduction were investigated based on the computational platform, which is one of the parametric modeling methods. The computational platform helps the designers or engineers to evaluate the efficacy of the numerous alternative structural systems for irregular Super-Tall building, which is crucial in determining the capacity and the number of the supplemental damping devices for adding the required damping ratios to the building. The inherent damping ratio was estimated based on the related domestic and foreign researches conducted by using real wind-load records. Two types of damping devices were considered: One is inter-story installation type passive control devices and the other is mass type active control devices. The supplemental damping ratio due to the damping devices was calculated by means of equivalent static analysis using an equation suggested by FEMA. The optimal design of the damping devices was conducted by using the computational platform. The structural element quantity reduction effect resulting from the installation of the damping devices could be simply assessed by proposing a wind-load reduction factor, and the effectiveness of the proposed method was verified by a numerical example of a 455m high-rise building. The comparison between roof displacement and the story shear forces by the nonlinear time history analysis and the proposed method indicated that the proposed method could simply but approximately estimate the effects of the supplemental damping devices on the roof displacement and the member force reduction.

Statistical Analysis of Random Ship Rolling Using Equivalent Linearization Method (등가선형화방법을 이용한 선체의 불규칙 횡동요 운동의 통계적 해석)

  • Dong-Soo Kim;Won-Kyoung Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.30 no.4
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    • pp.39-45
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    • 1993
  • In order to analyze the rolling motion of a ship in random beam waves we have used the equivalent linearization method. The quadratic nonlinear damping, the cubic and quintic nonlinear restoring moments were added to a single degree of freedom linear equation of roll motion. The irregular excitation moment was assumed to be the Gaussian white noise. The statistical characteristic of the response by the equivalent linearization method was compared with the simulation result.

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Seismic Behavior of Steel Structure with Added Viscoelastic Dampers under Strong Earthquake Ground Motions (점탄성 감쇠기를 설치한 강구조 건물의 강지진 하중에 의한 거동 연구)

  • Oh, Soon Taek
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.2
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    • pp.111-120
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    • 1993
  • This paper summarizes an experimental and analytical study on the application of viscoelastic dampers as energy dissipation devices in structural applications. It can be concluded the viscoelastic dampers are effective in reducing excessive vibrations of structures under strong earthquake ground motions. It is also found that the modal strain energy method can be used to reliably predict the equivalent structural damping, and the seismic response of a viscoelastically damped structure can be accurately estimated by conventional modal analysis techniques. Based on the above studies, a design procedure for viscoelastically damped structures is presented. This design procedure fits naturally into the conventional structural design flow chart by including damping ratio as an additional design parameter.

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Nonlinear elements position detecting by error matrix method (오차행렬에 의한 비선형 요소 위치 파악에 관한 연구)

  • 변언섭;이상설;박윤식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.5
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    • pp.1104-1111
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    • 1990
  • A method to identify nonlinear elements position of a nonlinear system is presented. Nonlinear elements position can be identified by an equivalent error damping and stiffness matrices which are based on the equivalent linearization technique. The procedures of this technique are: (1) Obtain input force and system response. (2) Define error between the actual and linearized restoring forces. (3) Calculate linearized damping and stiffness coefficients to minimize the square error sum. Several examples are tested and found that these methods are very effective not only to locate the nonlinear elements position but also to identify the degree of nonlinearity qualitatively. Nonlinear type can be qualitatively identified by examining the plots of restoring force vs equivalent state values.

Probability Distribution of Displacement Response of Structures with Friction dampers Excited by Earthquake Loads Generated Using Kanai-Tajimi Filter (Kanai-Tajimi 필터 인공지진 가진된 마찰형 감쇠를 갖는 구조물의 변위 응답 확률분포)

  • Youn, Kyung-Jo;Park, Ji-Hun;Min, Kyung-Won;Lee, Sang-Hyun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.5
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    • pp.623-628
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    • 2007
  • The accurate peak response estimation of a seismically excited structure with frictional damping system(FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated that by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In the case that an earthquake load is defined with probabilistic characteristics, the corresponding response of the structure with FDS has probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake loads generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Finally, coefficients of the proposed PDF are obtained by regression analysis of the statistical distribution of the time history responses. Finally the correlation between PDFs and statistical response distribution is presented.

Determination of Structural Performance Point Utilizing The Seismic Isolation Rubber Bearing Design Method (면진격리 고무베어링 설계법을 이용한 구조물의 성능점 예측)

  • 김창훈;좌동훈
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.3
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    • pp.23-30
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    • 2003
  • The seismic base isolation design approach has been reviewed and modified to fit the nonlinear static analysis procedure for determination of the performance point of structures in a simpler way, such an adaptation may be possible for the fact that a structural system under development of damage due to earthquake loading keeps softening to result in period shifting toward longer side. The superiority of the proposed method to the state-of-the-practice approach is that the reasonably accurate performance point can be obtained without constructing the so-called acceleration displacement response spectrum required in application of capacity spectrum method. The validity of the proposed approach was verified by comparing the predicted values to the exact ones presented in the literature.

On the Damping of A Shock Absorption Device Composed of Disk Spring Stacks (디스크 스프링의 적층 배열에 따른 완충장치의 감쇠에 관한 연구)

  • Choi, Myung-Jin;Ko, Seok-Hoon
    • 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.

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