• Title, Summary, Keyword: matrix stiffness method

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Analysis of a Structural Damage Detection Using Sensitivity Analysis (감도해석을 이용한 구조물의 손상위치 및 크기해석)

  • 이정윤
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.6
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    • pp.50-55
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    • 2003
  • This study proposed the analysis of damage detection due to the change of the stiffness of structure by using the original and modified dynamic characteristics. The present approach allows the use of composite data which consist of eigenvalues and eigenvectors. The suggested method is applied to examples of a cantilever and 3 degree of freedom system by modifying the stiffness. The predicted damage detections are in good agreement with these from the structural reanalysis using the modified stiffness.

Analysis of a Structural Damage Detection using the Change of Dynamic Characteristics (동특성 변화를 이용한 구조물의 손상 탐지 해석)

  • 이정윤;이정우;이준호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.760-763
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    • 2003
  • This study proposed the analysis of damage defection due to the change of the stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the stiffness. The predicted damage detections are in good agreement with these from the structural reanalysis using the modified stiffness.

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Inelastic Buckling Analysis of Semi-rigid Frames with Shear Deformations by Haringx's Theories (Haringx의 전단변형 이론을 고려한 부분강절 뼈대구조의 비탄성 좌굴해석)

  • Min, Byoung-Cheol
    • Journal of the Korean Society of Safety
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    • v.29 no.3
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    • pp.64-71
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    • 2014
  • The generalized tangential stiffness matrix of semi-rigid frame element with shear deformations based on Haringx's shear theory is newly derived and compared with the previous study based on Engesser's shear theory. Also, linearized elastic and geometric stiffness matrices are newly presented from the exact tangential stiffness matrix. In oder to obtain the inelastic system buckling load of shear flexible semi-rigid frame structure, the Ef method by tangential modulus theory is adopted and the FE analysis programs are developed. Finally, the shear and semi-rigid effects of system bucking are investigated by two numerical examples.

Dynamic stiffness matrix of an axially loaded slenderdouble-beam element

  • Jun, Li;Hongxing, Hua;Xiaobin, Li
    • Structural Engineering and Mechanics
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    • v.35 no.6
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    • pp.717-733
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    • 2010
  • The dynamic stiffness matrix is formulated for an axially loaded slender double-beam element in which both beams are homogeneous, prismatic and of the same length by directly solving the governing differential equations of motion of the double-beam element. The Bernoulli-Euler beam theory is used to define the dynamic behaviors of the beams and the effects of the mass of springs and axial force are taken into account in the formulation. The dynamic stiffness method is used for calculation of the exact natural frequencies and mode shapes of the double-beam systems. Numerical results are given for a particular example of axially loaded double-beam system under a variety of boundary conditions, and the exact numerical solutions are shown for the natural frequencies and normal mode shapes. The effects of the axial force and boundary conditions are extensively discussed.

Shape Finding Analysis of Pneumatic Structure (공기막 구조물의 형상해석)

  • 권택진;서삼열;이장복
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.57-64
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    • 1994
  • The purpose of this paper is to find minimum surface shape of pneumatic structure using the finite element method. The pneumatic membrane structure is a kind of large deformation problem and very flexible composite material, which mean geomatric nonlinearity. It is not to resist for compression and resultant moment. As the displacement due to internal pressure is getting bigger, it should be considered the direction of forces. It becomes non-linear problem with the non-conservative force. The follower-force depends on the deformation and the direction of force is normal to each element. The solution process is obtained the new stiffness matrix (load correction matrix) depending on deformation through each iterated step. However, the stiffness matrix have not the symmetry and influence on the time of covergence. So in this paper Newton-Rhapson method for solving non-linear problem and for using symmetic matrix, the load direction is changed in each iterated step using the transformation matrix.

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Geometrically nonlinear analysis of plane frames composed of flexibly connected members

  • Gorgun, H.
    • Structural Engineering and Mechanics
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    • v.45 no.3
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    • pp.277-309
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    • 2013
  • Beam-to-column connections behaviour plays an important role in the analysis and design of steel and precast concrete structures. The paper presents a computer-based method for geometrically nonlinear frames with semi-rigid beam-to-column connections. The analytical procedure employs modified stability functions to model the effect of axial force on the stiffness of members. The member modified stiffness matrix, and the modified fixed end forces for various loads were found. The linear and nonlinear analyses were applied for two planar steel structures. The method is readily implemented on a computer using matrix structural analysis techniques and is applicable for the efficient nonlinear analysis of frameworks.

New Nonlinear Analysis Algorithm Using Equivalent Load for Stiffness (강성등가하중을 이용한 새로운 비선형해석 알고리즘)

  • Kim, Yeong-Min;Kim, Chee-Kyeong;Kim, Tae-Jin
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.6
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    • pp.731-742
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    • 2007
  • This paper presents a new nonlinear analysis algorithm, that is, adaptive Newton-Raphson iteration method, The presented algorithm is based on the existing Newton-Raphson method, and the concept of it can be summarized as calculating the equivalent load for stiffness(ELS) and adapting this to the initial global stiffness matrix which has already been calculated and saved in initial analysis and finally calculating the correction displacements for the nonlinear analysis, The key characteristics of the proposed algorithm is that it calculates the inverse matrix of the global stiffness matrix only once irresponsive of the number of load steps. The efficiency of the proposed algorithm depends on the ratio of the active Dofs - the Dofs which are directly connected to the members of which the element stiffness are changed - to the total Dofs, and based on this ratio by using the proposed algorithm as a complementary method to the existing algorithm the efficiency of the nonlinear analysis can be improved dramatically.

Investigation of the Stress-Wave Propagation In Improve the Reliability of the Impact-Echo Method (충격반향기법의 신뢰성 향상을 위한 탄성파 파동전파 특성의 연구)

  • 조미라
    • Journal of the Korea Concrete Institute
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    • v.14 no.2
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    • pp.266-274
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    • 2002
  • The impact-echo test, which is to evaluate the integrity of concrete and masonry structures nondestructively, is an excellent method in the practical application. However, there are cases that the Impact-Echo testing nay result in the low reliability. In this study, the reliability of the Impact-Echo testing was investigated through the numerical simulation of the Impact-Echo testing. The finite element analysis and the analysis based on the dynamic stiffness matrix method was incorporated for the numerical simulation, in which the cases of a sandwiched shear stiffness, an incr+easing or decreasing stiffness, and a homogeneous stiffness. Based on the results of the analysis were considered, this study proposed the approaches to Improve the reliability of the Impact-Echo testing.

Damage detection from the variation of parameter matrices estimated by incomplete FRF data

  • Rahmatalla, Salam;Eun, Hee-Chang;Lee, Eun-Taik
    • Smart Structures and Systems
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    • v.9 no.1
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    • pp.55-70
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    • 2012
  • It is not easy to experimentally obtain the FRF (Frequency Response Function) matrix corresponding to a full set of DOFs (degrees of freedom) for a dynamic system. Utilizing FRF data measured at specific positions, with DOFs less than that of the system, as constraints to describe a damaged system, this study identifies parameter matrices such as mass, stiffness and damping matrices of the system, and provides a damage identification method from their variations. The proposed parameter identification method is compared to Lee and Kim's method and Fritzen's method. The validity of the proposed damage identification method is illustrated in a simple dynamic system.

A Simple Analysis of the Cylindrical Shell Subjected to a Nonaxisymmetric Load (비축대칭 하중을 받는 원통형 쉘의 단순화 해석)

  • 남문희;이관희
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.2
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    • pp.179-187
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    • 2000
  • When one considers the property of the axisymmetry, an analysis of an axisymmetric shell subjected to unaxisymmetric loading can be employed to save time and computer memory space. If one considers the Fourier series of the circumference direction of loads and displacements, an axisymmetric tank subjected to a nonaxisymmetric load can be treated as a frame element. Using the Fourier series, the authors derived the stiffness matrix of the cylindrical shell subjected to unaxisymmetric loading by the usual finite element method, and converted the stiffness matrix of a frame element into a transfer matrix by rearranging the stiffness matrix to apply the transfer matrix method. Here the most significant purpose of this paper is to achieve the fewest number of simultaneous equations for analysing an axisymmetric shell subjected to a nonaxisymmetric load. The results of the proposed method of the analysis of the cylindrical shell subjected to a wind load and a water load show no differences when compared to the other methods.

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