• Title/Summary/Keyword: Truss

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Mechanical Behaviors under Compression in Wire-woven Bulk Kagome Truss PCMs (II) - Effects of Geometric and Material Imperfections - (벌크형 와이어직조 카고메 트러스 PCM의 압축거동 (II) - 결함의 영향 -)

  • Hyun, Sang-Il;Choi, Ji-Eun;Kang, Ki-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.7 s.262
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    • pp.792-799
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    • 2007
  • A newly developed cellular metal based on kagome lattice is an ideal candidate for multifunctional materials achieving various optimal properties. Intensive efforts have been devoted to develop efficient techniques for mass production due to its wide potential applications. Since a variety of imperfections would be inevitably included in the realistic fabrication processes, it is highly important to examine the correlation between the imperfections and material strengths. Previous performance tests were mostly done by numerical simulations such as finite element method (FEM), but only for perfect structures without any imperfection. In this paper, we developed an efficient numerical framework using nonlinear random network analysis (RNA) to verify how the statistical imperfections (geometrical and material property) contribute to the performance of general truss structures. The numerical results for kagome truss structures are compared with experimental measurements on 3-layerd WBK (wire-woven bulk kagome). The mechanical strength of the kagome structures is shown relatively stable with the Gaussian types of imperfections.

Damage Detection in Truss Structures using Anti-Optimization (역 최적화 방법을 이용한 트러스 구조물의 손상탐지)

  • Lee, Seung Hye;Lee, Jae Hong
    • Journal of Korean Society of Steel Construction
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    • v.25 no.4
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    • pp.441-449
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    • 2013
  • Damaged structures change the value of natural properties. The purpose of this study is to detect damage using the difference of natural properties between the healthy state and the damaged state. Anti-optimization method is used to find the conditions that maximize the difference in characteristics between the two contrasting models. In this paper, a algorithm for finding the loading conditions which can maximize the difference of strain energy between the healthy state and the damaged state of truss structures is developed. Numerical examples show that the proposed method is accurate and efficient for truss structures.

Analysis of Failure Mechanism for Wire-woven Bulk Kaogme (Wire-woven Bulk Kagome 의 파손 메커니즘 분석)

  • Lee, Byung-Kon;Choi, Ji-Eun;Kang, Ki-Ju;Jeon, In-Su
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1690-1695
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    • 2007
  • Lightweight metallic truss structures with open, periodic cell are currently being investigated because of their multi-functionality such as thermal management and load bearing. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. The subject of this paper is an examination of the failure mechanism of Wire woven Bulk Kagome(WBK). To address this issue, the out-of-plane compressive responses of the WBK has been measured and compared with theoretical and finite element (FE) predictions. For the experiment, 2 multi-layered WBK are fabricated and 3 specimens are prepared. For the theoretical analysis, the brazed joints of each wire in WBK are modeled as the pin-joint. Then, the peak stress of compressive behavior and elastic modulus are calculated based on the equilibrium equation and energy method. The mechanical structure with five by five cells on the plane are constructed is modeled using the commercial code, PATRAN 2005. and the analysis is achieved by the commercial FE code ABAQUS version 6.5 under the incremental theory of plasticity.

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Mechanical Behaviors under Compression in Wire-woven Bulk Kagome Truss PCMs-Part II: Effects of Geometric and Material Imperfections (벌크형 와이어직조 카고메 트러스 PCM 의 압축거동- 제 2 보: 결함의 영향)

  • Hyun, Sang-Il;Choi, Ji-Eun;Kang, Ki-Ju
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.78-83
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    • 2007
  • A newly developed cellular metal based on kagome lattice is an ideal candidate for multifunctional materials achieving various optimal properties. Intensive efforts have been devoted to develop efficient techniques for mass production due to its wide potential applications. Since a variety of imperfections would be inevitably included in the realistic fabrication processes, it is highly important to examine the correlation between the imperfections and material strengths. Previous performance tests were mostly done by numerical simulations such as finite element method (FEM), but only for perfect structures without any imperfection. In this paper, we developed an efficient numerical framework using nonlinear random network analysis (RNA) to verify how the statistical imperfections (geometrical and material property) contribute to the performance of general truss structures. The numerical results for kagome truss structures are compared with experimental measurements on 3-layerd WBK (wire-woven bulk kagome). The mechanical strength of the kagome structures is shown relatively stable with the Gaussian types of imperfections.

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Consequence-based robustness assessment of a steel truss bridge

  • Olmati, Pierluigi;Gkoumas, Konstantinos;Brando, Francesca;Cao, Liling
    • Steel and Composite Structures
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    • v.14 no.4
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    • pp.379-395
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    • 2013
  • Aim of this paper is to apply to a steel truss bridge a methodology that takes into account the consequences of extreme loads on structures, focusing on the influence that the loss of primary elements has on the structural load bearing capacity. In this context, the topic of structural robustness, intended as the capacity of a structure to withstand damages without suffering disproportionate response to the triggering causes while maintaining an assigned level of performance, becomes relevant. In the first part of this study, a brief literature review of the topics of structural robustness, collapse resistance and progressive collapse takes place, focusing on steel structures. In the second part, a procedure for the evaluation of the structural response and robustness of skeletal structures under impact loads is presented and tested in simple structures. Following that, an application focuses on a case study bridge, the extensively studied I-35W Minneapolis steel truss bridge. The bridge, which had a structural design particularly sensitive to extreme loads, recently collapsed for a series of other reasons, in part still under investigation. The applied method aims, in addition to the robustness assessment, at increasing the collapse resistance of the structure by testing alternative designs.

RAMS evaluation for a steel-truss arch high-speed railway bridge based on SHM system

  • Zhao, Han-Wei;Ding, You-Liang;Geng, Fang-Fang;Li, Ai-Qun
    • Structural Monitoring and Maintenance
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    • v.5 no.1
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    • pp.79-92
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    • 2018
  • The evaluation theory of reliability, availability, maintainability and safety (RAMS) as a mature theory of state evaluation in the railway engineering, can be well used to the evaluation, management, and maintenance of complicated structure like the long-span bridge structures on the high-speed railway. Taking a typical steel-truss arch bridge on the Beijing-Shanghai high-speed railway, the Nanjing Dashengguan Yangtze River Bridge, this paper developed a new method of state evaluation for the existing steel-truss arch high-speed railway bridge. The evaluation framework of serving state for the bridge structure is presented based on the RAMS theory. According to the failure-risk, safety/availability, maintenance of bridge members, the state evaluation method of each monitoring item is presented. The weights of the performance items and the monitoring items in all evaluation levels are obtained using the analytic hierarchy process. Finally, the comprehensive serving state of bridge structure is hierarchical evaluated.

Theoretical and experimental study on deflection of steel-concrete composite truss beams

  • Wang, Junli;Li, Tian;Luo, Lisheng
    • Steel and Composite Structures
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    • v.29 no.1
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    • pp.91-106
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    • 2018
  • This paper investigates the deflection of the steel-concrete composite truss beam (SCCTB) at the serviceability limit state. A precise solution for the distributed uplift force of the SCCTB, considering five different loading types, is first derived based on the differential and equilibrium equations. Furthermore, its approximate solution is proposed for practical applications. Subsequently, the shear slip effect corresponding to the shear stiffness of the stub connectors, uplift effect corresponding to the axial stiffness of the stub connectors and shear effect corresponding to the brace deformation of the steel truss are considered in the derivation of deflection. Formulae for estimating the SCCTB deflection are proposed. Moreover, based on the proposed formulae, a practical design method is developed to provide an effective and convenient tool for designers to estimate the SCCTB deflection. Flexure tests are carried out on three SCCTBs. It is observed that the SCCTB stiffness and ultimate load increase with an increase in the shear interaction factor. Finally, the reliability of the practical design method is accurately verified based on the available experimental results.

Structural Analysis of Space Truss by using New Force Method based on Singular Value Decomposition (특이값 분해로 정식화 된 새로운 하중법을 이용한 입체 트러스 구조 해석)

  • Lee, Su-Hyun;Chung, Woo-Sung;Lee, Jae-Hong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.5
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    • pp.481-489
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    • 2011
  • In this paper presents new force method by using singular value decomposition. The existing force method has some advantages about analysis of truss structures such as it is easier basic concept than finite element method, which apply to analyze truss structures. However, this method has complex formulation for analysis. Therefore, in this study proposes new force method using singular value decomposition, which is both having easy basic concept and simple computation than existing force method. The proposed method is illustrated through numerical examples.

Shear Behavior Prediction of Reinforced Concrete Beams by Transformation Angle Truss Model Considered Bending Moment Effect (휨모멘트 효과가 고려된 변환각 트러스 모델에 의한 철근콘크리트 보의 전단거동 예측)

  • 김상우;이정윤
    • Journal of the Korea Concrete Institute
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    • v.14 no.6
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    • pp.910-921
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    • 2002
  • For the prediction of shear behavior of reinforced concrete beams, this paper proposed Transformation Angle Truss Model (TATM) considered bending moment effect. Shear stress-strain relationship obtained from the TATM was agreed well with test results conducted by this study Further, shear strength obtained from the TATM was compared to the experimentally observed results of 170 reinforced concrete beams which had various shear span ratios shapes of support and shapes of cross section. The shear strength of reinforced concrete beams obtained from test was better predicted by the TATM with 0.96 in average and 11.9% in coefficient of variation than by other truss models. And the ratio of experimental results to theoretical results obtained from the TATM was almost constant regardless of the η and a/d.

Prediction of Deformation of Shear Reinforcement and Shear Crack Width of Reinforced Concrete Members using Truss Models (트러스 모델을 이용한 철근콘크리트 부재의 전단철근 및 전단균열폭의 변형 예측)

  • Kim, Sang-Woo;Lee, Jung-Yoon
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.3 s.13
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    • pp.49-56
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    • 2004
  • This paper predicted the shear deformation, such as strain of shear reinforcement and shear track width, of reinforced concrete (RC) members using Transformation Angle Truss Model (TATM) in order to apply to the shea, analysis of RC buildings. To check the validity of TATM for the shear deformation of RC beams, four RC beams with different shear span-to-depth ratios were cast, instrumented and tested. Observed results were compared with theoretical results by MCFT(Response-2000), RA-STM, FA-STM, and TATM. The proposed model, TATM, better predicted the relationships of the shear stress-strain of shear reinforcement and the shear stress-shear track width than other truss models.

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