• Title, Summary, Keyword: 조화하중

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High Frequency Approximation for Earthquake-Induced Hydrodynamic Loads in Rigid Stroage Tank (고주파수 근사해를 적용한 유체저장탱크에 작용하는 지진하중 산정)

  • 류정선;양우식
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.1-8
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    • 1999
  • The present paper describes an approximation for estimation of earthquake-induced hydrodynamic loads in rigid storage tank which accelerated in horizontal direction. The storage tank is vertically cylindrical, and the sectional shape may be circular, rectangular or irregular. The solution for harmonic excitation is studied based on velocity potential theory, and then the time domain solution for earthquake is obtained by using design response spectrum. As a result, earthquake load is influenced primarily by the inertia force of high frequency effective mass of the storage tank, responding to the characteristics of design response spectrum, tank sectional shape, and the ratio of tank base length to depth. Earthquake-induced hydrodynamic loads in rigid storage tank can be effectively obtained by using the high frequency approximation method in case of quite large, or small ratio of the tank base length to water depth.

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Linear Analysis and Non-linear Analysis with Co-Rotational Formulation for a Cantilevered Beam under Static/Dynamic Tip Loads (정적 및 동적 하중을 받는 외팔보 거동에 관한 선형 및 CR 정식화 비선형 예측의 비교)

  • Ko, Jeong-Woo;Bin, Young-Bin;Eun, Won-Jong;Shin, Sang-Joon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.5
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    • pp.467-475
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    • 2015
  • In this paper, the behaviour of a cantilevered beam was predicted to examine the difference between linear and non-linear static, dynamic analysis for a structure by using CR nonlinear formulation. Then, external transverse static and dynamic loads were applied at the free tip of the beam. Classical theories were used for the present linear analysis and co-rotational dynamic FEM program was used for the present nonlinear analysis. In the static analysis, effects of the load for the beam deflection were observed in both linear and nonlinear analysis. Then, normalized displacement at the tip of the beam was predicted for different frequency ratio and a significant difference was obtained in the vicinity of the resonant frequency. In addition, effects of frequency and time for the beam deflection were investigated to find the frequency delay.

Finite Element Modelling of a Submerged Cylindrical Structure Considering Fluid-Structure Interaction Effect and Dynamic Response Spectrum Analysis (유체-구조물 상호작용을 고려한 실린더형 수중 구조물의 유한요소모델링 및 동적 응답 스펙트럼 해석)

  • 이희남;신태명
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.1
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    • pp.1-9
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    • 2001
  • 유체-구조물 상호작용 효과를 고려하여, 실린더형 수중 구조물의 유한요소 모델을 상용 전산코드를 사용하여 작성하고 동적하중에 대한 응답해석을 수행하였다. 구조 유한요소에 부착되는 유체 유한요소로 인하여 발생하는 요소행렬의 비대칭성으로 인하여, 일반적으로 사용되는 유한요소 해석 전산코드로 유체-구조물 상호작용 모델에 대한 응답스펙트럼해석을 수행하는 것은 불가능하다. 이 문제의 해결을 위하여, 등가 비 유체-구조물 상호작용 모델을 구성하고, 등가비 유체-구조물 상호작용 모델에 대한 응답스펙트럼 해석 및 조화가진 응답해석 결과를 이용하여 유체-구조물 상호작용 모델의 스펙트럼 가진에 대한 동적 응답을 계산할 수 있는 효율적인 방법을 제시하였다.

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경계요소법에 의한 대규모 3차원 지하구조물의 동적해석

  • 한국전산구조공학회
    • Computational Structural Engineering
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    • v.8 no.3
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    • pp.11-21
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    • 1995
  • 3차원 대규모 지하구조물의 동적응답을 결정하기 위한 일반적인 수치해석이 제안되었다. 지반과 구조물을 해석하기 위하여 Laplace 변환을 적용한 경계요소법을 설명하였고, 지반-구조물계에 작용하는 외부 동적하중과 지진파를 고려할 수 있도록 공식화하였다. 동적교란이 전파되는 경우에 시간영역의 응답을 얻기 위하여는 구해진 변화된 해를 수치적인 Laplce 역변환을 수행하여야 하지만 동적교란이 조화적인 경우에는 응답이 주파수 영역으로부터 직접 얻어지며, 역변환이 필요하지 않다. 이 방법의 특징은 높은 정확도와 효율성이며, 지반-구조물계에 대하여 초기조건 및 점탄성 재료의 거동을 쉽게 고려할 수 있다는 것이다. 그러므로 이 방법은 다양한 지하구조물의 동적거동과 지진에 대한 취약함을 연구하기 위한 적절한 도구로 사용되어 질 수 있다.

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Sound Radiation From Infinite Beams Under the Action of Harmonic Point Forces (조화집중하중을 받는 무한보에서의 음향방사)

  • 김병삼;홍동표
    • Journal of KSNVE
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    • v.2 no.1
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    • pp.33-39
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    • 1992
  • The problem of sound radiation from infinite elastic beams under the action of harmonic point forces is studied. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z = 0 and to be axially infinite. The beam material and the elastic foundation re assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio$(\gamma)$ and stiffness factor$(\Psi)$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

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Sound Radiation From Infinite Beams Under the Action of Harmonic Moving Line Forces (조화분포이동하중을 받는 무한보에서의 음향방사)

  • 김병삼;이태근;홍동표
    • Journal of KSNVE
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    • v.3 no.3
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    • pp.245-251
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    • 1993
  • The problem of sound radiation from infinite elastic beams under the action on harmonic moving line forces is studies. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z=0 and to be axially infinite. The beam material and elastic foundation are assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results examined as a function of Mach number (M), wavenumber ratio$(\gamma{)}$ and stiffness factor $(\Psi{)}$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

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Sound radiation of curved beam under the action of harmonic line forces (조화분포하중을 받는 원환보의 음향방사)

  • 지창헌
    • Journal of the Korean Society of Safety
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    • v.12 no.3
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    • pp.10-16
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    • 1997
  • The problem of sound radiation from curved beam under the action of harmonic line forces is studied. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y=0. The curved beam material and the elastic foundation are assumed to be lossless including a tension force(T), damping coefficient(C) and stiffness of foundation($k_s$) will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire curved beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio($\gamma$) and stiffness factor($\psi$).

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Development of Macro-Element for the Analysis of Elastically Supported Plates (탄성 지지된 판구조 해석을 위한 매크로 요소의 개발)

  • 강영종;박남회;앙기재;최진유
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.1
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    • pp.25-35
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    • 2000
  • The superstructure of general bridge like slab bridge and slab on girder bridge is composed of elastically supported isotropic plate. The objective of this study is to develop the new analysis method for elastically supported plate with general edge beam or girder(boundaries) under arbitrary out of plane loading. The displacement solutions for the macro-element of plate and beam are obtained by solving for the unknown interactive forces and moments at the beam or nodal line locations after satisfying equilibrium equation along the nodal line. The displacement functions for macro-elements ate proposed in single Fourier series using harmonic analysis, and the equilibrium equations of nodal line are composed by using slope-deflection method. The proposed analysis method is programmed by MS-Fortran and can be applied to all types of isotropic decks with bridge-type boundaries. Numerical examples involving elastically supported plates with various aspect ratio, loading cases, and bridge-type boundary conditions are presented to demonstrate the accuracy of this program. The major advantage of this new analysis method is the development of a simple solution algorithm, leads to obtain rapidly responses of bridge deck system. This proposed method can be used in parametric study of behavior of bridge decks.

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Design of Friction Dampers installed at a Multi-Story Building under Seismic Load (지진하중을 받는 다층 건물에 설치된 마찰감쇠기 설계)

  • Seong, Ji-Young;Min, Kyung-Won
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.4
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    • pp.457-462
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    • 2011
  • In this study, a simplified design procedure for friction dampers of a multi-story structure in order to reduce seismic response is proposed. To get insight for control effect of the structure with friction dampers is difficult, because of a nonlinear characteristic by a friction damper. Since a control force of a friction damper is influenced by coupling velocity between floors, adjoining modes are coupled. Thus structural response are derived by assuming steady-state response in resonance. As it is impossible that an exact solution is obtained for seismic load, first, a closed form solution can be achieved under harmonic vibration. Second, to convert a three-story building into a single-degree-of-freedom(SDOF) structure, modal analysis is performed. Third, an equivalent damping ratio is derived with utilizing closed form solution. And response reducing factor is proposed by it. Finally, friction force of a damper is designed for using response reducing factor, and then designed dampers are verified for seven seismic data. The nonlinear analysis results confirm the validity of the proposed procedure.

Seismic Response Control of Arch Structures using Semi-active TMD (준능동 TMD를 이용한 아치구조물의 지진응답제어)

  • Kang, Joo-Won;Kim, Gee-Cheol;Kim, Hyun-Su
    • Journal of the Korean Association for Spatial Structures
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    • v.10 no.1
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    • pp.103-110
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    • 2010
  • In this study, the possibility of seismic response control of semi-active tuned mass damper (TMD) for spatial structures has been investigated. To this end, an arch structure was used as an example structure because it has primary characteristics of spatial structures and it is a comparatively simple structure. A TMD and semi-active TMD were applied to the example arch structure and the seismic control performance of them were evaluated based on the numerical simulation. In order to regulate the damping force of the semi-active TMD, groundhook control algorithm, which is widely used for semi-active control, was used. El Centro (1940) and Northridge (1994) earthquakes and harmonic ground motion were used for performance evaluation of passive TMD and semi-active TMD. Based on the analytical results, the passive TMD could effectively reduce the seismic responses of the arch structure and it has been shown that the semi-active TMD more effectively decreased the dynamic responses of the arch structure compared to the passive TMD with respect to all the excitations used in this study.

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