• Title/Summary/Keyword: space structures

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Initial Shape Design of Space Truss Structure using Density Method (밀도법을 이용한 스페이스 트러스 구조물의 초기 형상 설계)

  • Kim, Ho-Soo;Park, Young-Sin;Yang, Myung-Kyu;Lee, Min-Ho;Kim, Jae-Yoon
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.4
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    • pp.59-66
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    • 2010
  • This study presents the topology optimization technique by density method to determine the initial shape of space truss structures. Most initial shape design is performed by designer's previous experiences and trial and error method instead of the application of reasonable optimization method. Thus, the reasonable and economical optimization methods are needed to be introduced for the initial shape design. Therefore, we set design domain for cantilever space truss structure as an example model. And topology optimization is used to obtain optimum layout for them, and then size optimization method is used to find the optimum member size. Therefore, the reasonable initial optimal shapes of spatial truss structures can be obtained through the topology and size optimization using density method.

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MODULI OF SELF-DUAL METRICS ON COMPLEX HYPERBOLIC MANIFOLDS

  • Kim, Jaeman
    • Bulletin of the Korean Mathematical Society
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    • v.39 no.1
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    • pp.133-140
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    • 2002
  • On compact complex hyperbolic manifolds of complex dimension two, we show that the dimension of the space of infinitesimal deformations of self-dual conformal structures is smaller than that of the deformation obstruction space and that every self-dual metric with covariantly constant Ricci tensor must be a standard one upto rescalings and diffeomorphisms.

A Study on the Critical Point and Bifurcation According to Load Mode of Dome-Typed Space Frame Structures (돔형 스페이스 프레임 구조물의 하중모드에 따른 분기점 특성에 관한 연구)

  • Shon, Su-Deok;Kim, Seung-Deog;Lee, Seung-Jae;Kim, Jong-Sik
    • Journal of Korean Association for Spatial Structures
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    • v.11 no.1
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    • pp.121-130
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    • 2011
  • Space frame structures have the advantage of constructing a large space structures without column and it may be considered as a shell structure. Nevertheless, with the characteristics of thin and long term of spacing, the unstable problem of space structure could not be set up clearly, and there is a huge difference between theory and experiment. Therefore, in this work, the tangential stiffness matrix of space frame structures is studied to solve the instability problem, and the nonlinear incremental analysis of the structures considering rise-span ratio(${\mu}$) and the ratio of load($R_L$) is performed for searching unstable points. Basing on the results of the example, global buckling can be happened by low rise-span ratio(${\mu}$), nodal buckling can be occurred by high rise-span ratio(${\mu}$). And in case of multi node space structure applying the ratio of load($R_L$), the nodal buckling phenomenon occur at low the ratio of load($R_L$), the global buckling occur a1 high the ratio of load($R_L$). In case of the global buckling, the load of bifurcation is about from 50% to 70% of perfect one's snap-through load.

A Study to Derive Energetics of Coronal Magnetic Structures

  • Kang, Jihye;Magara, Tetsuya;Inoue, Satoshi;Lee, Hwanhee;An, Jun-Mo
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.127.2-127.2
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    • 2012
  • Space weather prediction related to flares and CMEs is an important issue these days. It is, however, hard to estimate magnetic energy of invisible coronal magnetic structure. The virial theorem is one of the ways to determine the magnetic energy. In this study, we performed a series of MHD simulation of an emerging flux tube and apply the virial theorem to the simulation results and derive energetics of coronal structures. We then analyze real observational data on NOAA 11302 to derive the distributions of physical quantities, such as density, temperature, velocity and magnetic field. We also use knowledge form simulation analysis to estimate the magnetic energy of NOAA 11302.

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A Study of Unstable Phenomenon of Flow Truss Dome Structure with Asymmetric Load Modes (Flow Truss Dome 구조물의 비대칭 하중모드에 따른 불안정 현상에 관한 연구)

  • Shon, Su-Deok;Kim, Seung-Deog;Kang, Moon-Myung
    • Journal of Korean Association for Spatial Structures
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    • v.2 no.4 s.6
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    • pp.61-76
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    • 2002
  • The structure system that is discreterized by continuous shells is usually used to make a large space structures and these structures show the collapse mechanisms that are captured at over the limit load, and snap-through and bifurcation are most well known of it. For the collapse mechanism, rise-span ratio, element stiffness and load mode are main factor, which it give an effect to unstable behavior. Moreover, resist force of structure can be reduced by initial condition and initial imperfection significantly. In order to investigate the instability of shell structures, the finite deformation theory can be applied and it becomes a nonlinear mathematics in which use equation of tangential stiffness incrementally. With an initial imperfection, using simple example and Flow Truss Dome, the buckling characteristics of space truss is main purpose of this paper, and unstable behavior is studied by proposed the numerical method. Also, by using MIDAS, this research work analyzes displacements and inner forces as the design load of model, and the ratio of buckling load of design load is investigated.

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A Case Study of Retraction Controlled Wind Velocity on the Steel Retractable Roof of Large Span (강성개폐식 대공간 지붕의 개폐 관리풍속 사례 분석)

  • Song, Jin-Young;Yoon, Sung-Won
    • Journal of Korean Association for Spatial Structures
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    • v.18 no.1
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    • pp.93-100
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    • 2018
  • The retractable roof structures have actions of various types of loads and external forces depending on the retraction and operation conditions of the roof in terms of efficiency of control and maintenance as the aspect of structural plan. In particular, there is a need for studies on the establishment of retraction controlled wind velocity to maintain the stable control and usability of roof structure against strong winds or sudden gusts during the retraction of the roof. In this paper, it was intended to provide basic materials for the development of guidelines on the operation and maintenance of domestic retractable buildings with large space by analyzing the factors affecting the retraction controlled wind velocity for the overseas stadiums with the large spatial retractable roof structures where the sliding system was applied on the steel retractable systems. As a result, the controlled wind velocity tends to decrease as the retractable roof area increases. On the other hand, the controlled wind velocity tends to increase as the retraction time increases. In addition, in the space-grid roof structures, the spherical roof structures type showed the average controlled wind velocity of 10m/sec lower than that of 17.3m/sec for curved-roof structure type, and in the curved-roof structure type, the truss roof structure showed the average controlled wind velocity of 8.9m/sec which is lower than that of 17.3m/sec for the space for the space-grid roof structure.

ON FIBRED KAEHLERIAN SPACES

  • Choi, Jin Hyuk
    • Journal of the Chungcheong Mathematical Society
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    • v.19 no.4
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    • pp.417-426
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    • 2006
  • In this paper, we are to construct a new fibred Riemannian space with almost complex structure from the lift of an almost contact structures of the base space and that of each fibre. Moreover, we deal with the fibred Riemannian space with various Kaehlerian structure.

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Simulated squirrel search algorithm: A hybrid metaheuristic method and its application to steel space truss optimization

  • Pauletto, Mateus P.;Kripka, Moacir
    • Steel and Composite Structures
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    • v.45 no.4
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    • pp.579-590
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    • 2022
  • One of the biggest problems in structural steel calculation is the design of structures using the lowest possible material weight, making this a slow and costly process. To achieve this objective, several optimization methods have been developed and tested. Nevertheless, a method that performs very efficiently when applied to different problems is not yet available. Based on this assumption, this work proposes a hybrid metaheuristic algorithm for geometric and dimensional optimization of space trusses, called Simulated Squirrel Search Algorithm, which consists of an association of the well-established neighborhood shifting algorithm (Simulated Annealing) with a recently developed promising population algorithm (Squirrel Search Algorithm, or SSA). In this study, two models are tried, being respectively, a classical model from the literature (25-bar space truss) and a roof system composed of space trusses. The structures are subjected to resistance and displacement constraints. A penalty function using Fuzzy Logic (FL) is investigated. Comparative analyses are performed between the Squirrel Search Algorithm (SSSA) and other optimization methods present in the literature. The results obtained indicate that the proposed method can be competitive with other heuristics.

Dynamic Characteristics of Space Framed Structures by Using Nonlinear Transient Analysis (비선형 과도해석을 이용한 스페이스 프레임 구조물의 동적특성)

  • Son, Jin Hee;Kim, Joo-Woo
    • Journal of Korean Society of Steel Construction
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    • v.28 no.6
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    • pp.395-402
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    • 2016
  • Space frame structures considering the components such as forms, layers, grids, etc. are possible to form a large space without interior columns. Here, steels having the yield strengths of 210 MPa to 450 MPa are generally used. The high strength steel (i.e., yield strength of 690 MPa) having suitable weldability, aseismicity and economics have been recently developed. In this paper, the high strength steel is applied to the space frame structures in order to analytically find out their transient responses considering the material and geometric nonlinearities. For various circular dome types of space frame structures, the modal analysis and nonlinear transient analysis are carried out using nonlinear three dimensional finite element analysis.