• Title, Summary, Keyword: Non-linear dynamic analysis

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Earthquake performance evaluation of three-dimensional roller compacted concrete dams

  • Kartal, Murat Emre;Karabulut, Muhammet
    • Earthquakes and Structures
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    • v.14 no.2
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    • pp.167-178
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    • 2018
  • A roller compacted concrete (RCC) dam should be analyzed under seismic ground motions for different conditions such as empty reservoir and full reservoir conditions. This study presents three-dimensional earthquake response and performance of a RCC dam considering materially non-linearity. For this purpose, Cine RCC dam constructed in Aydın, Turkey, is selected in applications. The three-dimensional finite element model of Cine RCC dam is obtained using ANSYS software. The Drucker-Prager material model is considered in the materially nonlinear time history analyses for concrete and foundation rock. Furthermore, hydrodynamic effect was investigated in linear and non-linear dynamic analyses. Researchers observe that how the tensile and compressive stresses change by hydrodynamic pressure effect. The hydrodynamic pressure of the reservoir water is modeled with the fluid finite elements based on the Lagrangian approach. In this study, dam body and foundation are modeled with welded contact. The displacements and principle stress components obtained from the linear and non-linear analyses with and without reservoir water are compared each other. Principle stresses during earthquake were obtained at the most critical point in the upstream face of dam body. Besides, the change of displacements and stresses by crest length were investigated. Moreover demand-capacity ratio criteria were also studied under linear dynamic and nonlinear analysis. Earthquake performance analyses were carried out for different cases and evaluated. According to linear and nonlinear analysis, hydrodynamic water effect is obvious in full reservoir situation. On the other hand, higher tensile stresses were observed in linear analyses and then non-linear analyses were performed and compared with each other.

Dynamic Analysis of an Automatic Dynamic Balancer in a Rotor with the Bending Flexibility (축의 굽힘효과를 고려한 회전체에 장착된 자동평형장치의 동적해석)

  • Jeong, Jin-Tae;Bang, In-Chang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.7
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    • pp.1125-1130
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    • 2001
  • Dynamic behaviors of an automatic dynamic balancer are analyzed by a theoretical approach. Using the polar coordinates, the non-linear equations of motion for an automatic dynamic balancer equipped in a rotor with the bending flexibility are derived from Lagrange equation. Based on the non-linear equation, the stability analysis is performed by using the perturbation method. The stability results are verified by computing dynamic response. The time responses are computed from the non-linear equations by using a time integration method. We also investigate the effect of the bending flexibility on the dynamics of the automatic dynamic balancer.

Dynamic Non-Linear Analysis of Ocean Cables Subjected to Earthquakes (지진력을 받는 해양케이블의 동적 비선형해석)

  • 김남일;신현목
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.77-86
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    • 1999
  • In the previous $paper^{(1),(2)}$, a geometrically non-linear finite element formulation of spatial cables subjected to self-weights and support motions was presented using multiple noded cable elements and how to determine the initial equililbrium state of cables was addressed. In this paper, in order to perform dynamic non-linear analysis of ocean cables subjected to support motions and earthquakes, a numerical method to calculate Morison forces and incorporate effects of earthquake motions is presented based on the Newmark method. Challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to support motions and earthquake loadings.

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A Strength Analysis of a Hull Girder in a Rough Sea

  • Kim, Sa-Soo;Shin, Ku-Kyun;Son, Sung-Wan
    • Selected Papers of The Society of Naval Architects of Korea
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    • v.2 no.1
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    • pp.79-105
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    • 1994
  • A ship in waves is suffered from the various wave loads that comes from its motion throughout its life. Because these loads are dynamic, the analysis of a ship structure must be considered as the dynamic problem precisely. In the rationally-based design, the dynamic structural analysis is carried out using dynamic wave loads provided from the results of the ship motion calculation as a rigid body. This method is based on the linear theory assumed low wave height and small amplitude of motion. But at the rough sea condition, high wave height, compared with ship's depth, induce the large ship motion, so the ship section configuration under waterline is rapidly changed at each time. This results in a non-linear problem. Considering above situation in this paper, a strength analysis method is introduced for the hull girder among waves considering non-linear hydrodynamic forces. This paper evaluates the overall or primary level of the ship structural dynamic loading and dynamic response provided from the non-linear wave forces, and bottom flare impact forces by momentum slamming theory. For numerical calculation a ship is idealized as a hollow thin-walled box beam using thin walled beam theory and the finite element method is used. This method applied to a 40,000 ton double hull tanker and attention is paid to the influence of the response of the ship's speed, wave length and wave height compared with the linear strip theory.

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Dynamic Analysis of a Geometrical Non-Linear Plate Using the Continuous-Time System Identification

  • Lim, Jae-Hoon;Choi, Yeon-Sun
    • Journal of Mechanical Science and Technology
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    • v.20 no.11
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    • pp.1813-1822
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    • 2006
  • The dynamic analysis of a plate with non-linearity due to large deformation was investigated in this study. There have been many theoretical and numerical analyses of the non-linear dynamic behavior of plates examining theoretically or numerically. The problem is how correctly an analytical model can represent the dynamic characteristics of the actual system. To address the issue, the continuous-time system identification technique was used to generate non-linear models, for stiffness and damping terms, and to explain the observed behaviors with single mode assumption after comparing experimental results with the numerical results of a linear plate model.

Dynamic Analysis of a Geometrical Non-linear Plate (기하학적 비선형성을 갖는 평판의 동특성 해석)

  • 임재훈;최연선
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.498-503
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    • 2003
  • Dynamic analysis of a plate with non-linearity due to large deformation is performed in the study. There have been many researches about the non-linear dynamic behavior of plates examining by means of theoretical or numerical analyses. But it is important how exactly model the actual system. In this respect, the Continuous-Time system identification technique is used to generate non-linear models, for stiffness and damping terms, to explain the observed behaviors with single mode assumptions for the simplicity after comparing the experimental results with the numerical results of a linear plate model.

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A study on response analysis of submerged floating tunnel with linear and nonlinear cables

  • Yarramsetty, Poorna Chandra Rao;Domala, Vamshikrishna;Poluraju, P.;Sharma, R.
    • Ocean Systems Engineering
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    • v.9 no.3
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    • pp.219-240
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    • 2019
  • This paper presents the comparison between SFT response with linear and nonlinear cables. The dynamic response analysis of submerged floating tunnel (SFT) is presented computationally with linear and nonlinear tension legs cables. The analysis is performed computationally for two wave directions one at 90 degrees (perpendicular) to tunnel and other at 45 degrees to the tunnel. The tension legs or cables are assumed as linear and non- linear and the analysis is also performed by assuming one tension leg or cable is failed. The Response Amplitude Operators (RAO's) are computed for first order waves, second order waves for both failure and non-failure case of cables. For first order waves- the SFT response is higher for sway and heave degree of freedom with nonlinear cables as compared with linear cables. For second order waves the SFT response in sway degree of freedom is bit higher response with linear cables as compared with nonlinear cables and the SFT in heave degree of freedom has higher response at low time periods with nonlinear cables as compared with linear cables. For irregular waves the power spectral densities (PSD's) has been computed for sway and heave degrees of freedom, at $45^0$ wave direction PSD's are higher with linear cables as compared with nonlinear cables and at $90^0$ wave direction the PSD's are higher with non-linear cables. The mooring force responses are also computed in y and z directions for linear and nonlinear cables.

Ride Sensitivity Analysis of a Train With Non-linear Suspension Elements (비선형 현가요소를 가진 철도차량의 승차감 민감도 해석)

  • 전형호;탁태오
    • Journal of the Korean Society for Railway
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    • v.5 no.1
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    • pp.40-47
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    • 2002
  • In this study, and analytical method for ride sensitivity analysis of a train with non-linear suspension elements are proposed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train are parameterized using polynomial interpolation. Vertical dynamic model of a three-body train running on straight rail with the predetermined roughness expressed in terms of spectral density function is set up and its equations of motion for ride analysis are derived. Using the direct differentiation method, sensitivity equations of the vertical dynamic model with respect to design parameters associated with non-linearity of suspensions are obtained. Based on the sensitivity analysis, improvement of ride is achieved by varying appropriate suspension parameters.

FFT-based Spectral Analysis Method for Linear Discrete Structural Dynamics Models with Non-Proportional Damping (비 비례적 감쇠를 갖는 선형 이산 구조동력학 모델에 대한 FFT-활용 스펙트럴해석법)

  • Lee U-sik;Cho Joo-yong
    • Journal of the Korean Society for Railway
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    • v.9 no.1
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    • pp.63-68
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    • 2006
  • This paper proposes a fast Fourier transform(FFT)-based spectral analysis method(SAM) for the dynamic responses of the linear discrete dynamic models with non-proportional damping. The SAM was developed by using discrete Fourier transform(DFT)-theory. To verify the proposed SAM, a three-DOF system with non-proportional viscous damping is considered as an illustrative example. The present SAM is evaluated by comparing the dynamic responses obtained by SAM with those obtained by Runge-Kutta method.

Dynamic Analysis of Steel Jackets under Wave and Earthquake Loadings I : Linear and Non-linear F. E. Formulation (파랑 및 지진하중을 받는 스틸자켓의 동적해석 I : 선형 및 비선형 유한요소 정식화)

  • 김문영;백인열;고진석
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.5
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    • pp.1-11
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    • 2001
  • The purpose of this study is to develop the main program and pre/post processor for the geometric and plastic non-linear analysis of steel jacket structures subjected to wave and earthquake loadings. In this paper, steel jackets are modelled using geometric non-linear space frames and wave loadings re evaluated based on Morrison equation using the linear Airy theory and the fifth Stokes theory. Random wave is generated using JONSWAP spectrum. For earthquake analysis, dynamic analysis is performed using artificial earthquake time history. Also the plastic hinge method is presented for limit analysis of steel jacket. In the companion paper, the pre/post processor is developed and the numerical examples are presented for linear and non-linear dynamic analysis of steel jackets.

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