• Title, Summary, Keyword: geometric non-linear stiffness

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Nonlinear Analysis of IPS System using the multi-noded cable element (다절점 케이블요소를 이용한 IPS 시스템의 비선형 해석)

  • Lee Jun-Seok;Kim Moon-Young;Han Man-Yop;Kim Sung-Bo;Kim Nak-Kyung
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.623-630
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    • 2006
  • In this paper, a geometric nonlinear analysis procedure of beam-column element including multi-noded cable element is presented. For this, first a stiffness matrix about beam-column element which considers the second effect of initial force supposing the curved shape at each time step with Hermitian polynomials as the shape function is derived and second, tangent stiffness matrix about multi-noded cable element being too. To verify geometric nonlinearity of this newly developed multi-noded cable-truss element, IPS(Innovative Prestressed Support) system using this theory is analysed by geometric nonlinear method and the results are compared with those by linear analysis.

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FINITE ELEMENT ANALYSIS AND MEASUREMENT ON THE RELEASE OF RESIDUAL STRESS AND NON-LINEAR BEHAVIOR IN WELDMENTS BY MECHANICAL LOADING(I) - EXPERIMENTAL EXAMINATION -

  • Jang, Kyoung-Bok;Yoon, Hun-Sung;Cho, Sang-Myoung
    • Proceedings of the KWS Conference
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    • pp.372-377
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    • 2002
  • Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

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A Study on Non-linear Behavior in Welded Structures by Mechanical Stress Release Method (기계적 응력 완화법에 의한 용접구조물의 비선형 거동에 관한 연구)

  • 김정현;장경복;윤훈성;강성수;조상명
    • Journal of Welding and Joining
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    • v.21 no.1
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    • pp.66-71
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    • 2003
  • The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure fur steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test and the proper degree of stress relaxation was measured by sectioning technique using strain gauge. Analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result.

Vibration and Post-buckling Behavior of Laminated Composite Doubly Curved Shell Structures

  • Kundu, Chinmay Kumar;Han, Jae-Hung
    • Advanced Composite Materials
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    • v.18 no.1
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    • pp.21-42
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    • 2009
  • The vibration characteristics of post-buckled laminated composite doubly curved shells are investigated. The finite element method is used for the analysis of post-buckling and free vibration of post-buckled laminated shells. The geometric non-linear finite element model includes the general non-linear terms in the strain-displacement relationships. The shell geometry used in the present formulation is derived using an orthogonal curvilinear coordinate system. Based on the principle of virtual work the non-linear finite element equations are derived. Arc-length method is implemented to capture the load-displacement equilibrium curve. The vibration characteristics of post-buckled shell are performed using tangent stiffness obtained from the converged deflection. The code is first validated and then employed to generate numerical results. Parametric studies are performed to analyze the snapping and vibration characteristics. The relationship between loads and fundamental frequencies and between loads and the corresponding displacements are determined for various parameters such as thickness ratio and shallowness.

Buckling analysis of functionally graded truncated conical shells under external displacement-dependent pressure

  • Khayat, Majid;Poorveis, Davood;Moradi, Shapour
    • Steel and Composite Structures
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    • v.23 no.1
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    • pp.1-16
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    • 2017
  • This paper is presented to solve the buckling problem of functionally graded truncated conical shells subjected to displacement-dependent pressure which remains normal to the shell middle surface throughout the deformation process by the semi-analytical finite strip method. Material properties are assumed to be temperature dependent, and varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The governing equations are derived based on first-order shear deformation theory which accounts for through thickness shear flexibility with Sanders-type of kinematic nonlinearity. The element linear and geometric stiffness matrices are obtained using virtual work expression for functionally graded materials. The load stiffness also called pressure stiffness matrix which accounts for variation of load direction is derived for each strip and after assembling, global load stiffness matrix of the shell which may be un-symmetric is formed. The un-symmetric parts which are due to load non-uniformity and unconstrained boundaries have been separated. A detailed parametric study is carried out to quantify the effects of power-law index of functional graded material and shell geometry variations on the difference between follower and non-follower lateral buckling pressures. The results indicate that considering pressure stiffness which arises from follower action of pressure causes considerable reduction in estimating buckling pressure.

Geometric Non-linear Analysis of the Plane Frame Structures including Shear Deformation Effect (전단변형(剪斷變形)을 고려(考慮)한 평면(平面)뼈대 구조물(構造物)의 기하적(幾何的)인 비선형(非線形) 해석(解析))

  • Kim, Moon Young;Chang, Sung Pil
    • Journal of The Korean Society of Civil Engineers
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    • v.10 no.1
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    • pp.27-36
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    • 1990
  • Two beam/column elements in order to analyze the geometric nonlinear plane framed structures including the effects of transverse shear deformation and bending stretching coupling are developed. In the case of the first element (finite segment method), tangent stiffness matrix are derived by directly integrating the equilibrium equations whereas in the case of the second element (finite element method) elastic and geometric stiffness matrices are calculated by using the hermitian polynomials including shear deformation effect as the shape function. Both elements possess the usual six degree of freedoms. Numerical results are presented for the selected test problems which demonstrate that both elements represent reliable and highly accurate tools.

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Geometric nonlinear analysis of steel structures with external pretension using the multi-noded cable element (다절점 케이블요소를 이용한 외부 긴장된 강구조 시스템의 기하학적 비선형해석)

  • Lee, Jun Seok;Kim, Moon Young;Han, Man Yop;Kim, Sung Bo;Kim, Nak Kyung
    • Journal of Korean Society of Steel Construction
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    • v.18 no.6
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    • pp.727-735
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    • 2006
  • In this paper, a geometric nonlinear analysis procedure of the beam-column element including multi-noded cable element in extension of companion paper (Kim et al., 2005) is presented. First, a stiffness matrix was derived about the beam-column element that considers the second effect of the initial force supposing the curved shape at each time-step, with Hermitian polynomials as the shape function. Second, the multi-noded cable element was also subjected to the tangent stiffness matrix. To verify the geometric nonlinearity of this newly developed multi-noded cable-truss element, the Innovative Prestressed Support (IPS) system using this theory was analysed by geometric nonlinear method and the results were compared with those produced by linear analysis.

Mechanical Characteristics of Cable Truss Roof Systems (케이블 트러스 지붕 시스템의 역학적 특성)

  • Park, Kang-Geun;Lee, Dong-Woo
    • Journal of Korean Association for Spatial Structures
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    • v.16 no.2
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    • pp.89-96
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    • 2016
  • Cable structures are lightweight structures of flexible type, cable members have only axial stiffness related to tension, they can carry neither bending nor compression. This study is the analysis of cable truss systems are composed of upper and low cables by connecting bracing cables, the structural principle is based on a tensegrity system by using bracing tension members, discontinuous compression members and continuous tension members. A hanging roof of cable truss system is too flexible against vertical loads, most cable members are stabilized by connecting the prestressed upper and lower cable by bracing cables. A cable truss roof system is formed by adding a set of cables with reverse curvature to the suspension cables. With the sets of cables having opposite curvature to each other, cable truss is able to carry vertical load in both upward and downward direction with equal effectiveness, and then a cable truss acts as load bearing elements by the assemble of ridge cables, valley cables and bracing cables. This paper will be shown the geometric non-linear analysis result of cable truss systems with various sag ratio for deflections and tensile forces, the analytical results are compared with the results of other researchers.

Geometric Non-linear Analysis of Plane Frame Structures subjected to Conservative and Non-conservative Forces (보존력(保存力) 및 비보존력(非保存力)을 받는 평면(平面)뼈대 구조물(構造物)의 기하적(幾何的) 비선형(非線形) 해석(解析))

  • Kim, Moon Young;Chang, Sung Pil
    • Journal of The Korean Society of Civil Engineers
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    • v.10 no.1
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    • pp.17-26
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    • 1990
  • A solution strategy for geometric non-linear analysis for the plane frame structures subjected to conservative and non-conservative forces is presented. By making efficient combination of the load incremental method and the displacement incremental method, this strategy can find postbuckling configuration such as snap-through and turning-back phenomena which cannot be easily found by the conventional load and displacement incrementation scheme. In the case of the analysis of the framed structure subjected to circulatory non-conservative forces, the total tangent stiffness matrix becomes unsymmetric and when calculating the incremental load and unbalanced load vector components, the direction change of the non-conservative forces is considered. Several example problems to demonstrate the feasibility of the present strategy, over ranges of deformation that are well beyond those likly to occur in practical framed structures, are given and discussed.

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Numerical Studies of the Rotational Stiffness of Purlin-Sheeting System

  • Wang, Feiliang;Zhang, Hanwen;Yang, Jian;Bai, Li;Ren, Chong
    • International journal of steel structures
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    • v.18 no.3
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    • pp.719-733
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    • 2018
  • In light-gauged steel purlin-to-sheeting roof systems, the attached sheeting can provide rotational restraints to the purlin. The magnitude of the additional rotational stiffness offered by the sheeting will affect the load bearing capacity of the purlin. The current design method in Eurocode3 (EC3) is less accurate in predicting the purlin-sheeting rotational stiffness as it neglects the effect of wall thickness of the purlin. An integral model is introduced based on the finite element method. Comparisons are made between numerical results and existing experiments and a good agreement is observed. Parametric studies are conducted based on the validated model to investigate the influences of geometric dimensions on the rotational stiffness. Two modified coefficients are proposed for calculating the rotational stiffness based on the codified formulae in EC3, where the effect of the wall thickness and the flange width of the purlin are both considered.