• Title/Summary/Keyword: progressive deformation

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Evaluation of Post-Buckling Residual Strength of H-Section Steel Column for Both Ends are Fixed Condition (양단고정 단부구속에 따른 H 형 강재기둥의 좌굴 후 잔존내력 평가)

  • Abebe, Daniel Yeshewawork;Choi, Jae Hyouk;Kim, Jin Hyang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.1
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    • pp.83-88
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    • 2013
  • Progressive collapse is a chain reaction of failures propagating throughout a portion of a structure that is disproportionate to the original local failure. When column members are subjected to unexpected load (compression load), they will buckle if the applied load is greater than the critical load that induces buckling. The post-buckling strength of the columns will decrease rapidly, but if there is enough residual strength, the members will absorb the potential energy generated by the impact load to prevent progressive collapse. Thus, it is necessary to identify the relationship of the load-deformation of a column member in the progressive collapse of a structure up to final collapse. In this study, we carried out nonlinear FEM analysis and based on deflection theory, we investigated the load-deformation relationship of H-section steel columns when both ends were fixed.

Progressive failure of symmetric laminates under in-plane shear: Il-Negative shear

  • Singh, S.B.;Kumar, Ashwini;Iyengar, N.G.R.
    • Structural Engineering and Mechanics
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    • v.6 no.7
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    • pp.757-772
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    • 1998
  • The objective of the present work is to estimate the strength and failure characteristics of symmetric thin square laminates under negative shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with the finite element method. First-order shear-deformation theory along with geometric nonlinearity in the von Karman sense has been incorporated in the finite element modeling. Failure loads, associated maximum transverse displacements, locations and modes of failure including the onset of delamination are discussed in detail; these are found to be quite different from those for the positive sheer load reported in Part I of this study (Singh et al. 1998).

Experimental and numerical study on progressive collapse of composite steel-concrete frames

  • Jing-Xuan Wang;Ya-Jun Shen;Kan Zhou;Yong Yang
    • Steel and Composite Structures
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    • v.50 no.5
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    • pp.531-548
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    • 2024
  • This paper presents an experimental investigation into the progressive collapse behavior of composite steel-concrete frames under various column removal scenarios. This study involves testing two two-bay, two-story composite frames featuring CFST columns and profiled steel decking composite slabs. Two removal scenarios, involving the corner column and middle column, are examined. The paper reports on the overall and local failure modes, vertical force-deformation responses, and strain development observed during testing. Findings indicate that structural failure initiates due to fracture and local buckling of the steel beam. Moreover, the collapse resistance and ductility of the middle column removal scenario surpass those of the corner column removal scenario. Subsequent numerical analysis reveals the significant contribution of the composite slab to collapse resistance and capacity. Additionally, it is found that horizontal boundary conditions notably influence the collapse resistance in the middle column removal scenario only. Finally, the paper proposes a simplified calculation method for collapse resistance, which yields satisfactory predictions.

A Study on Thermal Ratcheting Structure Test of 316L Test Cylinder (316L 시험원통의 열라체팅 구조시험에 관한 연구)

  • Lee, H.Y.;Kim, J.B.;Koo, G.H.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.243-249
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    • 2001
  • In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature liquid metal reactor was simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The inelastic deformation of the reactor baffle cylinder can occur due to the moving temperature distribution along the axial direction as the hot free surface moves up and down under the cyclic heat-up and cool-down of reactor operations. The ratchet deformations were measured with the laser displacement sensor and LVDTs after cooling the structural specimen which experiences thermal load up to $550^{\circ}$ and the temperature differences of about $500^{\circ}C$. During structural thermal ratchet test, the temperature distribution of the test cylinder along the axial direction was measured from 28 channels of thermocouples and the temperatures were used for the ratchet analysis. The thermal ratchet deformation analysis was performed with the NONSTA code whose constitutive model is nonlinear combined kinematic and isotropic hardening model and the test results were compared with those of the analysis. Thermal ratchet test was carried out with respect to 9 cycles of thermal loading and the maximum residual displacements were measured to be 1.8mm. It was shown that thermal ratchet load can cause a progressive deformation to the reactor structure. The analysis results with the combined hardening model were in reasonable agreement with those of the tests.

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Recrystallization Behaviors of Ordered and Disordered Structures in Ll2 Type Ni3Fe Alloy (Ll2형 Ni3Fe 합금에서 규칙격자와 불규칙격자의 재결정거동)

  • Choi, C.S.;Kang, S.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.4 no.2
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    • pp.47-53
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    • 1991
  • Recrystallization behaviors of ordered and disordered structures in $Ll_2$ type $Ni_3Fe$ alloy were studied through hardness measurement and differential thermal analysis. When the disordered structure was isothermally aged at $480^{\circ}C$ below order-disorder transition temperature, the hardness of the structure was increased due to progressive ordering with increasing aging time. The hardness of the disordered structure was increased rapidly with increasing deformation degree up to 10%, and then gradually increased with further deformation degree. while the hardness of the ordered structure was increased rapidly with increasing deformation degree up to 10%, showing a constant hardness value up to 50% and gradually decreased with further deformation degree. The hardness of the ordered structure was higher than that of the disordered structure at all same deformation degrees. The recrystallization temperature of the ordered and disordered structures were decreased with increasing deformation degree. At the same deformation degrees, the recrystallization temperature of the ordered structure was lower than that of the desordered structure.

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Analytical Evaluation of Residual Strength for Steel Frame in case of Column Member Loss (기둥손실에 따른 철골프레임 잔존내력의 해석적 평가)

  • Park, Hwon-Mo;Yeshewawork, D.;Kim, Hyun-Soo;Choi, Jae-Hyouk
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.6
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    • pp.675-683
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    • 2011
  • When impacts by falling objects are applied to the structures, vertical resisting member(column or column group) results in progressive collapse. By knowing clearly load-deformation relationship of a structural frame, to prevent progressive collapse by absorbing potential energy of falling objects though column groups are lost by the impact of falling object accidently. If residual strength in vertical direction exceeds vertical load, which the sum of the weight of falling objects and usual supportive vertical load as the result of absorbing released location energy, it does not result in progressive collapse. On the other hand, in case when weight of falling objects is included in usual supportive vertical load. In this paper, 1-story 4-spans model is analyzed by non-linear FEM and to examine the level of deterioration, limit analysis of 1-story 4-spans plane frame was carried out.

Press and Die Deformation for a Precise Semiconductor Lead Frame (반도체 산업의 정밀리드프레임에 대한 프레스 및 금형 변형 예측)

  • Hong, S.;Yoon, Y.;Eom, S.;Hwang, J.;Lee, D.
    • Transactions of Materials Processing
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    • v.23 no.4
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    • pp.206-210
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    • 2014
  • The metal lead frame, a semiconductor component, has product tolerances in micro units as compared to products made with a larger size mold. Therefore, small deflections of the mold and of the press as well as the press molding process itself have a strong influence on accuracy of the product. Hence, it is necessary for the process design to consider the structural response of the mold and the press during deformation. In the current study, the mold deflection and pressure on the punch is examined using the finite element modeling (FEM) program ABAQUS. The results from the simulation were verified with the dynamic deformation measurement equipment using digital image correlation (DIC).

Analyses of centrifuge modelling for artificially sensitive clay slopes

  • Park, Dong Soon
    • Geomechanics and Engineering
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    • v.16 no.5
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    • pp.513-525
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    • 2018
  • Slope stability of sensitive clayey soils is particularly important when subjected to strength loss and deformation. Except for progressive failure, for most sensitive and insensitive slopes, it is important to review the feasibility of conventional analysis methods based on peak strength since peak strength governs slope stability before yielding. In this study, as a part of efforts to understand the behavior of sensitive clay slopes, a total of 12 centrifuge tests were performed for artificially sensitive and insensitive clay slopes using San Francisco Bay Mud (PI = 50) and Yolo Loam (PI = 10). In terms of slope stability, the results were analyzed using the updated instability factor ($N_I$). $N_I$ using equivalent unit weight to cause a failure is in reasonable agreement shown in the Taylor's chart ($N_I$ ~ 5.5). In terms of dynamic deformation, it is shown that two-way sliding is a more accurate approach than conventional one-way sliding. Two-way sliding may relate to diffused shear surfaces. The outcome of this study is contributable to analyzing stability and deformation of steep sensitive clay slopes.

Characteristic Analysis of Permanent Deformation in Railway Track Soil Subgrade Using Cyclic Triaxial Compression Tests (국내 철도 노반 흙재료의 반복재하에 따른 영구변형 발생 특성 및 상관성 분석)

  • Park, Jae Beom;Choi, Chan Yong;Kim, Dae Sung;Cho, Ho Jin;Lim, Yu Jin
    • Journal of the Korean Society for Railway
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    • v.20 no.1
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    • pp.64-75
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    • 2017
  • The role of a track subgrade is to provide bearing capacity and distribute load transferred to lower foundation soils. Track subgrade soils are usually compacted by heavy mechanical machines in the field, such that sometimes they are attributed to progressive residual settlement during the service after construction completion of the railway track. The progressive residual settlement generated in the upper part of a track subgrade is mostly non-recoverable plastic deformation, which causes unstable conditions such as track irregularity. Nonetheless, up to now no design code for allowable residual settlement of subgrade in a railway trackbed has been proposed based on mechanical testing, such as repetitive triaxial testing. At this time, to check the DOC or stiffness of the soil, field test criteria for compacted track subgrade are composed of data from RPBT and field compaction testing. However, the field test criteria do not provide critical design values obtained from mechanical test results that can offer correct information about allowable permanent deformation. In this study, a test procedure is proposed for permanent deformation of compacted subgrade soil that is used usually in railway trackbed in the laboratory using repetitive triaxial testing. To develop the test procedure, an FEA was performed to obtain the shear stress ratio (${\tau}/{\tau}_f$) and the confining stress (${\sigma}_3$) on the top of the subgrade. Comprehensive repetitive triaxial tests were performed using the proposed test procedure on several field subgrade soils obtained in construction sites of railway trackbeds. A permanent deformation model was proposed using the test results for the railway track.