• 제목/요약/키워드: Cross-tables

검색결과 77건 처리시간 0.019초

Bicriteria optimal design of open cross sections of cold-formed thin-walled beams

  • Ostwald, M.;Magnucki, K.;Rodak, M.
    • Steel and Composite Structures
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    • 제7권1호
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    • pp.53-70
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    • 2007
  • This paper presents a analysis of the problem of optimal design of the beams with two I-type cross section shapes. These types of beams are simply supported and subject to pure bending. The strength and stability conditions were formulated and analytically solved in the form of mathematical equations. Both global and selected types of local stability forms were taken into account. The optimization problem was defined as bicriteria. The cross section area of the beam is the first objective function, while the deflection of the beam is the second. The geometric parameters of cross section were selected as the design variables. The set of constraints includes global and local stability conditions, the strength condition, and technological and constructional requirements in the form of geometric relations. The optimization problem was formulated and solved with the help of the Pareto concept of optimality. During the numerical calculations a set of optimal compromise solutions was generated. The numerical procedures include discrete and continuous sets of the design variables. Results of numerical analysis are presented in the form of tables, cross section outlines and diagrams. Results are discussed at the end of the work. These results may be useful for designers in optimal designing of thin-walled beams, increasing information required in the decision-making procedure.

Seismic and collapse analysis of a UHV transmission tower-line system under cross-fault ground motions

  • Tian, Li;Bi, Wenzhe;Liu, Juncai;Dong, Xu;Xin, Aiqiang
    • Earthquakes and Structures
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    • 제19권6호
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    • pp.445-457
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    • 2020
  • An ultra-high voltage (UHV) transmission system has the advantages of low circuitry loss, high bulk capacity and long-distance transmission capabilities over conventional transmission systems, but it is easier for this system to cross fault rupture zones and become damaged during earthquakes. This paper experimentally and numerically investigates the seismic responses and collapse failure of a UHV transmission tower-line system crossing a fault. A 1:25 reduced-scale model is constructed and tested by using shaking tables to evaluate the influence of the forward-directivity and fling-step effects on the responses of suspension-type towers. Furthermore, the collapse failure tests of the system under specific cross-fault scenarios are carried out. The corresponding finite element (FE) model is established in ABAQUS software and verified based on the Tian-Ma-Qu material model. The results reveal that the seismic responses of the transmission system under the cross-fault scenario are larger than those under the near-fault scenario, and the permanent ground displacements in the fling-step ground motions tend to magnify the seismic responses of the fault-crossing transmission system. The critical collapse peak ground acceleration (PGA), failure mode and weak position determined by the model experiment and numerical simulation are in relatively good agreement. The sequential failure of the members in Segments 4 and 5 leads to the collapse of the entire model, whereas other segments basically remain in the intact state.

Effects of geometric parameters on in-plane vibrations of two-stepped circular beams

  • Tufekci, Ekrem;Yigit, Oznur Ozdemirci
    • Structural Engineering and Mechanics
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    • 제42권2호
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    • pp.131-152
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    • 2012
  • In-plane free vibrations of circular beams with stepped cross-sections are investigated by using the exact analytical solution. The axial extension, transverse shear deformation and rotatory inertia effects are taken into account. The stepped arch is divided into a number of arches with constant cross-sections. The exact solution of the governing equations is obtained by the initial value method. Several examples of arches with different step ratios, different locations of the steps, boundary conditions, opening angles and slenderness ratios for the first few modes are presented to illustrate the validity and accuracy of the method. The effects of the geometric parameters on the natural frequencies are investigated in details. Several examples in the literature are solved and the results are given in tables. The agreement of the results is good for all examples considered. The mode transition phenomenon is also observed for the stepped arches. Some examples are solved also numerically by using the commercial finite element program ANSYS.

전단변형이 양단고정 변단면 기둥의 좌굴하중에 미치는 영향 (Effects of Shear Deformations on Buckling Loads of Tapered Columns with Both Clamped Ends)

  • 이병구;이태은;안대순
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2000년도 봄 학술발표회논문집
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    • pp.92-99
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    • 2000
  • The nondimensional differential equations governing the buckling loads of tapered columns with both clamped ends and its boundary conditions are derived, in which the effects of shear deformations are included. These equations are solved numerically using a numerical integration technique and a bracketing method to obtain the buckling loads of columns. Four types of cross-sectional shape are considered in the numerical examples. The parametric studies of shear deformation effects on the buckling loads such as cross-sectional shape factor, shear coefficient, ratio of modulus of elasticity, slenderness ratio and section ratio are reported in tables and figures.

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최적반력을 가지는 도어 씨일의 단면설계 (Design of Door Seal Section with Optimal Reaction Force)

  • 한근조;박영철;심재준
    • 한국자동차공학회논문집
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    • 제8권6호
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    • pp.165-175
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    • 2000
  • In order to improve the function of a door seal, its section design technique is discussed in this study, Its roles are prevention of an inflow of dusts, noise interception, insulation, wateproof, and the vibroisolating action which reduces vibration between the body and the door of a car while running, and the buffer action which sustain the proper reacting force as the door is closed. In this study, the optimal cross section of a door seal is designed using nonlinear finite element analysis (commercial finete element analysis program EASi-SEAL) and tables of orthogonal arralys with respect to relations between door and door seal to secure the satisfactory airtight property with the minimum force to shut the door.

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Frequency, bending and buckling loads of nanobeams with different cross sections

  • Civalek, Omer;Uzun, Busra;Yayli, M. Ozgur
    • Advances in nano research
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    • 제9권2호
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    • pp.91-104
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    • 2020
  • The bending, stability (buckling) and vibration response of nano sized beams is presented in this study based on the Eringen's nonlocal elasticity theory in conjunction with the Euler-Bernoulli beam theory. For this purpose, the bending, buckling and vibration problem of Euler-Bernoulli nanobeams are developed and solved on the basis of nonlocal elasticity theory. The effects of various parameters such as nonlocal parameter e0a, length of beam L, mode number n, distributed load q and cross-section on the bending, buckling and vibration behaviors of carbon nanotubes idealized as Euler-Bernoulli nanobeam is investigated. The transverse deflections, maximum transverse deflections, vibrational frequency and buckling load values of carbon nanotubes are given in tables and graphs.

전단변형이 변단면기둥의 좌굴하중에 미치는 영향 (Effects of Shear Deformations on Buckling Loads of Tapered Columns)

  • 이병구
    • 한국농공학회지
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    • 제36권4호
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    • pp.56-63
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    • 1994
  • The nondimensional differential equations governing the buckling loads of tapered columns and its houndarv conditions are derived, in which the effects of shear deformations are included. These equations are solved numerically using a numerical integration technique and a bracketing method to obtain the buckling loads of columns. Four types of cross-sectional shape with clamped-free end constraint are used in the numerical examples. The parametric studies of shear deformation effects on the buckling loads such as cross-sectional shape factor, shear coefficient, ratio of modulus of elasticity, slenderness ratio and section ratio are reported in tables and figures.

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Analytical solutions of in-plane static problems for non-uniform curved beams including axial and shear deformations

  • Tufekci, Ekrem;Arpaci, Alaeddin
    • Structural Engineering and Mechanics
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    • 제22권2호
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    • pp.131-150
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    • 2006
  • Exact analytical solutions for in-plane static problems of planar curved beams with variable curvatures and variable cross-sections are derived by using the initial value method. The governing equations include the axial extension and shear deformation effects. The fundamental matrix required by the initial value method is obtained analytically. Then, the displacements, slopes and stress resultants are found analytically along the beam axis by using the fundamental matrix. The results are given in analytical forms. In order to show the advantages of the method, some examples are solved and the results are compared with the existing results in the literature. One of the advantages of the proposed method is that the high degree of statically indeterminacy adds no extra difficulty to the solution. For some examples, the deformed shape along the beam axis is determined and plotted and also the slope and stress resultants are given in tables.

Effects of anisotropy and curvature on free vibration characteristics of laminated composite cylindrical shallow shells

  • Dogan, Ali;Arslan, H. Murat;Yerli, Huseyin R.
    • Structural Engineering and Mechanics
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    • 제35권4호
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    • pp.493-510
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    • 2010
  • This paper presents effects of anisotropy and curvature on free vibration characteristics of cross-ply laminated composite cylindrical shallow shells. Shallow shells have been considered for different lamination thickness, radius of curvature and elasticity ratio. First, kinematic relations of strains and deformation have been showed. Then, using Hamilton's principle, governing differential equations have been obtained for a general curved shell. In the next step, stress-strain relation for laminated, cross-ply composite shells has been given. By using some simplifications and assuming Fourier series as a displacement field, differential equations are solved by matrix algebra for shallow shells. The results obtained by this solution have been given tables and graphs. The comparisons made with the literature and finite element program (ANSYS).

Three-point bending of beams with consideration of the shear effect

  • Magnucki, Krzysztof;Paczos, Piotr;Wichniarek, Radosław
    • Steel and Composite Structures
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    • 제37권6호
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    • pp.733-740
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    • 2020
  • The subject of the paper pertains to simply supported beams with bisymmetrical cross sections under three-point bending with consideration of the shear effect. The deformation of a planar cross section of the beam is described taking into account the assumed nonlinear hypothesis-theory. Two differential equations of equilibrium are obtained based on the principle of stationary potential energy. This system is analytically solved and the shear coefficients and deflections of the beams are derived. Moreover, the Young's modules of the materials and deflections of the beams are experimentally determined on a test stand. The results of the studies are specified in tables and compared.