• Title, Summary, Keyword: 모우드가속도법

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Mathematical Theorem of Mode Acceleration Method (모우드 가속도법의 수학적 정리(定理))

  • 김태남
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.2
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    • pp.1-7
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    • 2003
  • Mode superposition method(MSM) is the most commonly used for solving linear response problems of structural dynamics. The major advantage of MSM is that usually a small number of lower mode is sufficient to analysis the response. However, the convergence is slow and many modes would be needed to give an accurate MSM in large structure with many degrees of freedom. The inaccuracies of MSM are caused by mode truncation in the solution. These demerits can be overcome by use of the mode acceleration method(MAM). Example analyses are carried out in simple beam subjected to harmonic loadings and compared the convergence of the joint displacements by the two methods. For relatively low frequency loadings, a good results was obtained by the lowest one mode in MAM, so the method is more economic in numerical analysis on an accurate solution.

Structural Dynamic Analysis by Ritz Vector Method Modified with Lanczos Algorithm (Lanczos 알고리즘을 도입한 Ritz Vector법에 의한 구조물의 동적해석)

  • 심재수;황의승;박주경
    • Computational Structural Engineering
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    • v.8 no.4
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    • pp.181-187
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    • 1995
  • Recent researches in dynamics are focused on finding effective methods to analyze the dynamic behavior of structures by fewer mode shapes their number of dgrees of freedom. Ritz algorithm and mode acceleration method were developed to improved the mode superposition. Ritz algorithm can include distribution of external loads but be apt to lose the orthogonality condition, which is useful properties in the analysis. Also mode acceleration method should consider a large number of mode shapes to get a satisfactory results. Another method, combining previous two method, was developed but too much computational efforts and times were required. The purpose of this study is to develop and evaluate the Ritz algorithm modified with the lanczos algorithm to improve the efficiency and accuracy. As a result of !this study, dynamic analysis using modified Ritz algorithm was proved to be the rational analysis method.

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Comparison of Mode Superposition Method and Mode Acceleration Method in Dynamic Analysis of Suspension Bridges under Wind Loads (풍하중을 받는 현수교의 진동 해석에 있어서 모우드 중첩법과 모우드 가속도법의 비교)

  • 김태남
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.223-230
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    • 1997
  • A method of stochastic dynamic analysis of suspension bridge subjected to random wind loads has been developed in this paper. Example analyses are carried out by mode superposition method(MSM), mode acceleration method(MAM) and advanced mode acceleration method(AMAM) in frequency domain for the Nam-Hae Bridge. In this study the statistical characterics of random wind loads we assumed to be Gaussian stationary zero mean processes. The considered structural response quanties are displacements, shear forces and bending moments. The mean extreme responses are approximately calculated by three times of standard deviations. The followings are the conclusions from this study. 1. Numerical results which obtained by three methods of computer program developed in this paper agree reasonably well when the numbers of modes increase. 2. AMAM is simple, accurate, economic and reliable method compared with the MSM and the MAM.

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