• Title, Summary, Keyword: mode superposition method

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3D Bridge-Vehicle interaction Analysis of Cable-Supported Bridges Using Mode Superposition Method (모드중첩법을 이용한 케이블지지교량의 3차원 교량-차량 상호작용 해석)

  • Lee Jun-Seok;Im Myoung-Hoon;Kim Moon-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.265-272
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    • 2005
  • For bridge-vehicle interaction analysis of cable-supported brides, the superposition method is applied based on the results of 3-dimensional free vibration analysis using General-purpose FEM Software. This study firstly performs the eigenvalue analysis for the free vertical and the torsional vibration of bridges using FEM analysis. Next the equations of motion considering interaction between bridges and vehicles/train are derived from mode superposition method. And then dynamic analysis is performed using the Newmark numericial method. Finally through the numerical examples, the dynamic responses of cable-supported bridges by this study are presented and discussed.

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Development of a Dynamic Simulation Program for Pantograph-Catenary System based on a Mode Superposition Method (모드중첩법을 기초로 한 집전성능해석 프로그램 개발)

  • 조용현;이기원;현승호;정흥채
    • Proceedings of the KSR Conference
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    • pp.606-617
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    • 2000
  • A dynamic simulation program for pantograph-catenary system is developed based on a mode superposition method to predict current collection performance. Formulations for the dynamic simulation are presented in this paper. The number of modes which should be considered for a KTX catenary system is reviewed through frequency response analyses. The responses for GPU pantograph - KTX catenary system are simulated with various train speeds. The our simulation results are in reasonably good agreements with RTRI simulation program, SNCF simulation program, and BR simulation program.

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Dynamic Response Analysis of Top-tensioned Riser Under Sheared Current Load (전단류 하중을 받는 상부장력 라이저의 동적 응답 해석)

  • Kim, Kookhyun
    • Journal of Ocean Engineering and Technology
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    • v.27 no.4
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    • pp.83-89
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    • 2013
  • A numerical scheme based on a mode superposition method is presented for the dynamic response analysis of a top-tensioned riser (TTR) under sheared current loads. The natural frequencies and mode shapes of the TTR have been calculated analytically for a beam with a slowly varying tension and pinned-pinned boundary conditions at the top and bottom ends. The lift coefficients and corresponding amplitudes used to estimate the vortex-induced modal force and damping for each mode were predicted via iterative calculations based on the input and output power balancing concept. Here, the power-in regions were controlled by the normal distribution function, for which the center was coincident with the lock -in location by local vortex-shedding, and the range was defined by the constant standard deviation for the reduced velocity by the local current speed. Finally, dynamic responses such as root-mean-squared displacement and stress were calculated using the mode superposition technique. In order to verify the presented scheme, a numerical calculation was performed for a TTR under an arbitrary linearly sheared current and linearly varying tension. A comparison with the results of the existing software showed that the presented scheme could give reliable and feasible solutions. Case studies were performed to investigate the effects of various current loads and tensions.

A Study on the Dynamic Impact Response Analysis of Cask by Modal Superposition Method (모드중첩기법을 이용한 CASK의 동적충격응답해석)

  • Lee Young-Shin;Kim Yong-Jae;Choi Young-Jin;Kim Wol-Tae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.4
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    • pp.373-383
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    • 2005
  • The cask is used to transfer the radioactive material in various fields required to withstand hypothetical accident condition such as 9m drop impact in accordance with the requirement of the domestic requlations and IAEA. So far the impact force has been obtained by the finite element method with complex computational procedure. In this study, the dynamic impact response of the cask body is analyzed using the mode superposition method, and the analysis method is proposed. The results we also validated by comparing with previous experimental results and finite element analysis results. The present method Is simpler than finite element method and can be used to predict the global impact response of cask

Response spectrum analysis considering non-classical damping in the base-isolated benchmark building

  • Chen, Huating;Tan, Ping;Ma, Haitao;Zhou, Fulin
    • Structural Engineering and Mechanics
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    • v.64 no.4
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    • pp.473-485
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    • 2017
  • An isolated building, composed of superstructure and isolation system which have very different damping properties, is typically non-classical damping system. This results in inapplicability of traditional response spectrum method for isolated buildings. A multidimensional response spectrum method based on complex mode superposition is herein introduced, which properly takes into account the non-classical damping feature in the structure and a new method is developed to estimate velocity spectra from the commonly used displacement or pseudo-acceleration spectra based on random vibration theory. The error of forced decoupling method, an approximated approach, is discussed in the viewpoint of energy transfer. From the base-isolated benchmark model, as a numerical example, application of the procedure is illustrated companying with comparison study of time-history method, forced decoupling method and the proposed method. The results show that the proposed method is valid, while forced decoupling approach can't reflect the characteristics of isolated buildings and may lead to insecurity of structures.

Flexibility Analysis of 4-Bar Linkage Mechanism (4절 링크기구의 유연성 해석)

  • 조선휘;박종근;한성현
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1365-1373
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    • 1994
  • Elasto-dynamic deformation of flexible linkage mechanism was analyzed using the finite element method. A computer program was constructed and applied to analyze a specific crank-level 4-bar mechanism, in which the elasto-dynamic deformation of the mechanism system was obtained using mode superposition method in the case of constant input speed and the effect of geometric stiffness on the mechanism is included. Experimental verification of numerical results was conducted by measuring the elasto-dynamic deformation of mid-points of coupler and lever for the 4-bar lingkage mechanism using high speed camera and image data processing systeem. For the elasto-dynamic deformation at the lever mid-point, the numerical results including geometric stiffness almost agree with the experimental ones. However, the numerical results excluding geometric stiffness good agree with the experimental ones at the couper mid-point.

Robust Design of Leaf Spring of a Polygon Mirror Scanner Motor Against Shock (충격에 강인한 폴리곤 미러 스캐너 모터의 판 스프링 설계)

  • Lee, Sang-Wook;Kim, Myung-Gyu;Jung, Kyung-Moon;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.515-520
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    • 2008
  • This paper develops a mite element model of a polygon mirror scanner motor supported by the sintered bearing and flexible supporting structures to analyze the shock response by using the finite element method and the mode superposition method. The validity of the proposed model is verified by comparing the simulated natural frequencies and shock response with the experimental ones. It investigates the displacement and the stress of the most vulnerable component, i.e. a leaf spring due to shock, and it proposes a robust design of leaf spring of a polygon mirror scanner motor against shock.

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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.

Extension of Direct Displacement-Based Design to Include Higher-Mode Effects in Planar Reinforced Concrete Frame Buildings

  • Abebe, Beka Hailu;Lee, Jong Seh
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.5
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    • pp.299-309
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    • 2018
  • Now that problems with force-based seismic design have been clearly identified, design is inclined toward displacement-based methods. One such widely used method is Direct-Displacement-Based Design (DDBD). Yet, one of the shortcomings of DDBD is considering higher-mode amplification of story shear, moments, and displacements using equations obtained from limited parametric studies of regular planar frames. In this paper, a different approach to account for higher-mode effects is proposed. This approach determines the lateral secant stiffness of the building frames that fulfill the allowable inter-story drift without exceeding the desired story displacements. Using the stiffness, an elastic response spectrum analysis is carried out to determine elastic higher-mode force effects. These force effects are then combined with DDBD-obtained first-mode force effects using the appropriate modal superposition method so that design can be performed. The proposed design procedure is verified using Nonlinear Time History Analysis (NTHA) of twelve planar frames in four categories accounting for mass and stiffness irregularity along the height. In general, the NTHA response outputs compared well with the allowable limits of the performance objective. Thus, it fulfills the aim of minimizing the use of NTHA for planar frame buildings, thereby saving computational resources and effort.

An Investigation into the Mode Superposition Method for the Foreced Transverse Vibration Analysis of Structures subject to the Timoshenko Beam Analogy (기준진동형중첩법(基準振動型重疊法)에 의한 Timoshenko보 유추(類推) 구조체(構造體)의 강제횡진동해석(强制橫振動解析))

  • K.C.,Kim;Y.I.,Park;H.M.,Kim;Y.J.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.20 no.1
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    • pp.21-27
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    • 1983
  • The mode superposition method(MSM) for the forced transverse vibration analysis of structures subject to Timoshenko beam analogy, which had originally been developed by Ormondroyd and McGoldrick, is reviewed to formulate it in more general form taking account of rotary inertia, dampings in separate terms of internal and external ones, and simultaneous action of exciting forces and moments. To investigate some general features of the method in practical utilizations, resonant maximum amplitudes of 4 high speed ships under concentrated sinusoidal excitation at the stern are calculated by both MSM and the finite difference method(FDM). For the FDM the hulls are discretized into 40 equal segments, and in utilization of MSM contributions of the first six modes are summed up to obtain responses up to the six-nodes resonant mode. The numerical results show that MSM gives slightly higher values, $4{\sim}10%$, than those by FDM. Since there is always uncertainty in the damping estimation of actual systems, influences of the damping magnitude on resonant amplitudes and a practical method to estimate modal damping coefficients are discussed.

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