• Title, Summary, Keyword: 비선형 동적해석

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Development of Nonlinear Dynamic Program for Buckling Analysis of Plane Circular Arches (평면 원호아치의 좌굴해석을 위한 동적 비선형해석 프로그램의 개발)

  • 허택녕;오순택
    • Computational Structural Engineering
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    • v.7 no.1
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    • pp.69-81
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    • 1994
  • This paper summarizes a dynamic analysis of the shallow circular arches under dynamic loading, considering the geometric nonlinearity. The major emphasis is placed on the development of computer program, which is utilized for the analysis of the nonlinear dynamic behavior and for the evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and a finite element analysis procedure is used to solve the dynamic equation of motion. A circular arch subject to normal step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of arches are estimated using the non-dimensional time, load and shape parameters and the results are also compared with those from the linear analysis. It is found that geometric nonlinearity plays and important role in the analysis of shallow arches and the probability of buckling failure is getting higher as arches become shallower.

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Dynamic Nonlinear Analysis of Stiffened Shell Structures (보강된 쉘구조의 동적 비선형해석)

  • 최명수;김문영;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.3
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    • pp.57-64
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    • 2001
  • For the dynamic nonlinear analysis of stiffened plate and shell structures, total Lagrangian formulation is presented based upon the degenerated shell element considering finite rotation effects. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. In the elasto-plastic analysis, the return mapping algorithm based on the consistent elasto-plastic tangent modulus is applied to collapse analysis of shell structures. Newmark integration method is used for dynamic nonlinear analysis of shell structures under dynamic forces.

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Model Analysis of R/C Framed Structures to Earthquake Excitations (지진하중을 받는 철근콘크리트 골조 구조물의 모드 해석)

  • 장극관;이리형
    • Magazine of the Korea Concrete Institute
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    • v.6 no.3
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    • pp.180-189
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    • 1994
  • An approximate method of normal coordinate idealization for use in nonlinear R /C frames has been developed. Normal coordinate apporaches have been used for nonlinear problems in the past, but they are not recerved wide acceptance because of the need for eigenvector computation in each time step. The proposed method circumvents the eigenvector recalculation problem by evaluating a limited number of sets of mode shapes in performing the dynamic analysis. Then some of the predetermined sets of eigenvectors are used in the nonlinear dynamic repeatedly. The method is applied to frame structures with ductile R /C elements. The plastic hinge zones are modeled with hysteres~s loops which evince degrading stiffness and pinching effects. Effxiencies and accuracies of the method for this application are presented.

Simplified Nonlinear Dynamic Progressive Collapse Analysis of Welded Steel Moment Frames Using Collapse Spectrum (붕괴스펙트럼을 활용한 용접철골모멘트골조의 비선형 동적 연쇄붕괴 근사해석)

  • Lee, Cheol Ho;Kim, Seon Woong;Lee, Kyung Koo;Han, Kyu Hong
    • Journal of Korean Society of Steel Construction
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    • v.21 no.3
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    • pp.267-275
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    • 2009
  • This paper presents the behavior of column-removed double-span beams in welded steel moment frames and proposes a simplified nonlinear dynamic analysis method for the preliminary evaluation of progressive collapse potential. The nonlinear finite element analysis and the associated analytical study showed that the column gravity load and the beam span-to-depth ratio govern the maximum dynamic deformation demand of the double-span beams. Based on these results, the concept of a collapse spectrum, which describes the relationship between the gravity load parameter and the maximum chord rotation of the double-span beams, was newly proposed. A procedure for the application of the collapse spectrum to multi-story welded steel moment frames was then suggested. The inelastic dynamic finite element analysis results showed that the proposed method gives satisfactory prediction of the nonlinear progressive collapse behavior of welded steel moment frames.

A Study on the Dynamic Characteristics of Tension Structures according to Initial Tension Forces and Equilibrium Shape (초기인장력과 평형형상을 고려한 인장구조물의 동적 특성에 대한 연구)

  • Chang, Dong Il;Kim, Hak Jae
    • Journal of Korean Society of Steel Construction
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    • v.10 no.1
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    • pp.73-83
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    • 1998
  • Considering dynamic behaviors according to initial tension forces, geometric nonlinearity and the effect of higher eigen modes to participate in dynamic behaviors increase as initial tension forces decrease, and from phase portrait we can realize that period attractors are produced in many area with complexity. If initial tension forxes increase, difference between linear and nonlinear solutions will decrease and the first eigen mode dominate the dynamic behaviors and observing phase portrait, period attractors appear in certain area regularly. These results may offer meaningful informations to nonlinear dynamic analysis using modal reduction methods such as Lanczos modal analysis. And actually nonlinear dynamic analysis needs very large computational efforts. So, if we determine the number of eigen modes to take part in modal analysis corresponding to initial tension forces we will get more accurate data close to exact nonlinear dynamic solutions.

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Prediction Approach with a Stiffness Measure in Nonlinear Dynamic Analysis of Reinforced Concrete Structures (철근 콘크리트 구조물의 비선형 동적 해석을 위한 성치 측정에 의한 예측 접근법)

  • 김교신;전경훈
    • Journal of the Earthquake Engineering Society of Korea
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    • v.1 no.1
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    • pp.1-10
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    • 1997
  • Current seismic design philosophy for reinforced concrete (RC) structures on energy dissipation through large inelastic defomations. A nonlinear dynamic analysis which is used to represent this behavior is time consuming and expensive, particularly if the computations have to be repeated many times. Therefore, the selection of an efficient yet accurate alogorithm becomes important. The main objective of the present study is to propose a new technique herein called the prediction approach with siffness measure (PASM) method in the convetional direct integration methods, the triangular decomposition of matrix is required for solving equations of motion in every time step or every iteration. The PASM method uses a limited number of predetermined decomposed effective matrices obtained from stiffness states of the structure when it is deformed into the nonlinear range by statically applied cyclic loading. The method to be developed herein will reduce the overall numerical effort when compared to approaches which recompute the stiffness in each time step or iteration.

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Earthquake Resistant Design of a Steel Framed Structure in Low Seismic Regions Based on the Dynamic Behaviour (동적거동에 기초한 약진지역 철골뼈대구조물의 내진설계)

  • 국승규
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.2
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    • pp.59-66
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    • 2001
  • 구조물 내진설계의 개념은 기존요구조건이라는 조항으로 시방서에 규정되어 있으며 구조물이 지진발생시에 안전성과 경제성을 최대한 확보할 수 있으며 비선형시간 이력해석을 수행하여 자진시의 동적거동을 기술함으로써 확인할 수 있다. 내진설계에 보편적으로 적용하는 응답스펙트럼해석법은 선형해석법으로 구조물의 비선형동적거동의 영향을 거동계수로 반영하므로 파괴메카니즘 및 기본 요구조건의 만족여부를 거동계수를 구하는 과정으로 결정할 수 있다. 이 연구에서는 내진설계방식에 의해 설계된 약진지역에 의한 화학공장건물의 모델인 3차원 철골뼈대구조물을 선정하고 거동계수를 결정하는 과정을 수행하여 지진시의 동적거동을 확인하였다. 이 연구의 결과, 현 시방서의 응답스펙트럼해석법에 적용되는 거동계수는 강진지역의 구조물의 경우 기능성 및 안정성 한계를 제시하지만 약진지역 구조물의 경우는 실제 동적거동과 무관하다는것과 약진 지역에 위치한 구조물의 내진설계에는 시방서가 제시한 내진설계방식을 적용하는 것이 주요한 사항임을 확인하였다.

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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 Study on Numerical Simulation for Dynamic Analysis of Towed Low-Tension Cable with Nonuniform Characteristics (불균일 단면을 갖는 저장력 예인케이블의 동적해석을 위한 수치해석적 연구)

  • 정동호
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.16 no.1
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    • pp.69-76
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    • 2003
  • Low-tension cables have been increasingly used in recent years due to deep-sea developments and the advent of synthetic cables. In the case of low-tension cables, large displacements may happen due to relatively small restoring forces of tension and thus the effects of fluid and geometric non-linearities and bending stiffness. A Fortran program is developed by employing a finite difference method. In the algorithm, an implicit time integration and Newton-Raphson iteration are adopted. For the calculation of huge size of matrices, block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with a in-house program of WHOI Cable with good agreements.

Effect of Nonlinear Analysis Procedures for Seismic Responses of Reinforced Concrete Wall Structure (철근콘크리트 벽체구조물의 지진응답에 대한 비선형 해석기법의 영향)

  • Song, Jong-Keol;Jang, Dong-Hui;Chung, Yeong-Hwa
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.4A
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    • pp.659-675
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    • 2006
  • Recently, significant progress has been made in performance-based engineering methods that rely mainly on nonlinear static seismic analysis procedures. The Capacity Spectrum Method (CSM) and the Displacement Coefficient Method (DCM) are the representative nonlinear static seismic analysis procedures. In order to evaluate the applicability of the procedures to the seismic evaluation and design process of new and existing structures, the accuracy of both CSM and DCM should be evaluated in advance. The accuracy of seismic responses by the nonlinear static procedures is evaluated in comparison with the shaking table test results for the structural wall specimen subjected to the far field and near field earthquakes. Also conducted are comparative studies where the shaking table test results are compared with those from nonlinear dynamic analysis procedures, i.e., Single-Degree-of-Freedom (SDOF), equivalent SDOF and Multi-Degree-of-Freedom (MDOF) systems.

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