• Title/Summary/Keyword: 등가감쇠

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Integrated Analysis and Design Technologies for a Structure with Control Devices (구조물-제진장치 통합 해석 및 설계 기술)

  • Lee, Sang-Hyun;Chung, Lan;Kang, Kyung-Soo;Hwang, Jae-Seung;Park, Ji-Hun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2010.04a
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    • pp.388-391
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    • 2010
  • 본 논문에서는 풍하중을 받는 구조물의 응답을 보다 적극적으로 저감시킴으로써 구조물의 안정성과 사용성을 개선하기위한 능동제어 알고리즘을 송도 자유무역 지구에 건설중인 포스코건설 사옥에 수치해석을 통해 적용하여 그 효과를 검증하였다. 수치해석에 의한 시뮬레이션 결과를 보면 최대 제어력이 제한이 된 비선형 제어기가 LQR 제어기와 등등한 제어효과를 가지고 있는 것으로 나타났으며, 제어력의 측면에서 본다면 비선형 제어기법이 더욱 유리한 것을 알 수 있다. 또한, 본 연구에서는 구조물과 질량형 제진장치의 상호작용을 고려하여 통합적으로 제진효과를 해석하고, 이를 바탕으로 제진장치를 설계할 수 있는 소프트웨어를 개발하였다. 구조물의 모드정보에 기초한 축소모델을 구축하고 제진장치의 설계 및 제진성능 평가를 수행하고 사용성을 평가하게 된다. 전체 소프트웨어는 질량형 제진장치의 설계프로그램과 질량형 제진장치의 종류별 대안설계결과를 등가감쇠비로 표현하여 비교평가하는 두 개의 모듈로 이루어져 있으며 전자는 비제어구조물 해석 모듈 및 TMD, TLD, TLCD, AMD를 대상으로 해석 및 설계를 수행하는 총 5개의 하부 모듈로 구성된다. 본 소프트웨어를 현재 TLCD가 설치되어 있는 인천 송도 국제업무지구의 주상복합건물에 적용하여 TMD, TLD, TLCD, AMD의 대안설계를 실시하였다.

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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.

Design of Friction Dampers for Seismic Response Control of a SDOF Building (단자유도 건물의 지진응답제어를 위한 마찰감쇠기 설계)

  • Min, Kyung-Won;Seong, Ji-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.1
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    • pp.22-28
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    • 2010
  • Approximate analysis for a building installed with a friction damper is performed to get insight of its dynamic behavior. Energy balance equation is used to have a closed analytical form solution of dynamic magnification factor(DMF). It is found out that DMF is dependent on friction force ratio and resonance frequency. Approximation of DMF and equivalent damping ratio of a friction damper is proposed with such assumption that the building with a friction damper shows harmonic steady-state response and narrow banded response behavior near resonance frequency. Linear transfer function from input external force to output building displacement is suggested from the simplified DMF equation. Root mean square of a building displacement is derived under earthquake-like random excitation. Finally, design procedure of a friction damper is proposed by finding friction force corresponding to target control ratio. Numerical analysis is carried out to verify the proposed design procedure.

Seismic Performance and Flexural Over-strength of Circular RC Column (원형 RC 기둥의 내진성능과 휨 초과강도)

  • Ko, Seong-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.49-58
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    • 2013
  • Eight small scale circular reinforced concrete columns were tested under cyclic lateral load with constant axial load. Test specimens were designed with 4.5 aspect ratio. The selected test variables are longitudinal steel ratio, transverse steel ratio, yielding strength of longitudinal steel and axial load ratio. The test results of columns with different longitudinal steel ratio, transverse steel ratio and axial load ratio showed different seismic performance such as equivalent damping ratio, residual displacement and effective stiffness. It was found that the column with low strength of longitudinal steel showed significantly reduced seismic performance, especially for equivalent damping ratio and residual displacement. The regulation of flexural over-strength is adopted by Korea Bridge Design Specifications (Limited state design, 2012). The test results are compared with nominal strength, result of nonlinear moment-curvature analysis and the design specifications such as AASHTO LRFD and Korea Bridge Design Specifications (Limited state design).

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.

Experimental study on the damping characteristics of a cylindrical structure containing oil and bearing balls (윤활유와 베어링 볼을 내장한 원통형 구조물의 감쇠특성에 관한 실험적 연구)

  • 류봉조;송선호
    • Journal of KSNVE
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    • v.6 no.1
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    • pp.107-114
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    • 1996
  • The damping characteristics of a cylindrical structure containing oil and bearing balls is investigated for external bending forces. The experimental data obtained through the use of bearing balls with viscous oil in a column is given and analyzed. The viscous action of the oil and inertia effects of the balls on the inside of column create a drag force. The drag force dampens the vibration of the column. This study aims to search for an optimum combination of oil and balls which would produce maximum damping. Machining oils of various viscosities along with ball bearings of various sizes place inside cantilevered aluminium tubes of various diameters to create a rig on which the damping properties of the oil and balls can be studied. The contileved tubes are studied in both horizontal and vertical positions in order to gauge the effect of gravity on the system. The actions of the ball in the column and damping characteristics are investigated according to the dimensionless terms. The Buckingham theorem is used to reduce the variables and to predict the damping of an oil ball column. Though the damping ratio remains fairly constant in the horizontal position of column, the damping ratio begins to increase as the ratio of the number of balls and column length rise above 0.28 in the vertical position of oil ball column. The ratio of the ball diameter to column diameter influences the damping ratio with an optimum diameter ratio. Slenderness ratio and gravity effects on the damping ratio ane investigated.

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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.

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.

A Study on the Seismic Analysis of Bridge with Lead Rubber Bearing (LRB(Lead Rubber Bearing)가 설치된 교량의 지진해석 연구)

  • Huh, Young;Park, Jin-Hyung
    • Proceedings of the KSR Conference
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    • 2000.11a
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    • pp.374-381
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    • 2000
  • 본 논문에서는 지진 발생시, LRB가 설치된 교량의 시간이력 해석을 수행하였다 이를 위해 LRB의 비선형 거동특성을 Bi-linear로 모형화 하였으며, 기존의 방법인 등가선형으로 모형화된 해석결과와 비교하였다. 또한 LRB받침만 설치된 경우와, LRB받침과 일반탄성받침이 함께 사용된 경우를 해석하여, 받침이 혼합된 경우, 상시하중과 지진하중시 발생할 수 있는 문제점을 검토하였다. 4경간 연속교량에 적용된 해석결과를 보면, LRB만을 설치한 경우, Pot-Bearing만 설치된 경우에 .비해, 고유주기 상승과 이력감쇠에 의한 지진력의 감소와 함께, 지진력의 효과적인 분배를 볼 수 있었으며, 일반탄성받침과의 적절한 조합에 의해서도, 충분한 면진성능을 얻을 수 있었다. 또한 LRB의 등가선형 모델이 Bi-linear 모델에 비해 보수적인 해석결과를 나타내었다.

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Equivalent Damping Ratio of the Inelastic SDOF Structures with Friction Damper (마찰감쇠기가 설치된 비선형 단자유도 건물의 등가감쇠비)

  • 김형섭;민경원;이상현;박지훈;문병욱
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.10a
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    • pp.492-499
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    • 2004
  • The purpose of this paper is to present a design procedure of coulomb friction dampers for controlling elastic and inelastic responses of building structures. The equivalent damping and frequency increased by the friction damper are estimated using ATC-40 and ATC-55 procedures which provide equivalent linear system for bilinear one, and then a design formula to achieve target performance response level by friction damper is presented. It is identified that there exists error between the responses obtained by this formula and by performing nonlinear analysis and the features of the error vary according to the hardening ratio, yield strength ratio, and structural period. Equations for compensating this er개r are reposed based on the least square method, and the results from numerical analyses indicate that the error is significantly reduced, and the proposed formula can be used without much error for designing coulomb friction damper for retrofitting a structure showing elastic or inelastic behavior.

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