• Title/Summary/Keyword: large deflection

검색결과 513건 처리시간 0.023초

Dynamic characteristics of elastic beams subjected to traffic loads

  • Tang, Chia-Chih;Wang, Yang-Cheng
    • Structural Engineering and Mechanics
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    • 제13권2호
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    • pp.211-230
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    • 2002
  • The objective of this study is to investigate the dynamic behavior of elastic beams subjected to moving loads. Although analytical methods are available, they have limitations with respect to complicated structures. The use of computer technology in recent years is an effective way to solve the problem; thus using the latest technology this study establishes a finite-element solution procedure to investigate dynamic behaviors of a typical elastic beam having a set of constant geometric properties and various span lengths. Both the dead load of the beam and traffic load are applied in which the traffic load is considered a concentrated moving force with various traveling passage speeds on the beam. Dynamic behaviors including deflection, shear, and bending moment due to moving loads are obtained by both analytical and finite element methods; for simple structures, they have an excellent agreement. The numerical results show that based on analytical methods the fundamental mode is good enough to estimate the dynamic deflection along the beam, but is not sufficient to simulate the total response of the shear force or the bending moment. The linear dynamic behavior of the elastic beams subjected to multiple exciting loads can easily be found by linear superposition, and the geometric nonlinear results caused by large deformation and axial force of the beam are always underestimated with only a few exceptions which are indicated. In order to make the results useful, they have been nondimensionalized and presented in graphical form.

Nonlinear behavior of deep reinforced concrete coupling beams

  • Zhao, Z.Z.;Kwan, A.K.H.
    • Structural Engineering and Mechanics
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    • 제15권2호
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    • pp.181-198
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    • 2003
  • Six large scale models of conventionally reinforced concrete coupling beams with span/depth ratios ranging from 1.17 to 2.00 were tested under monotonically applied shear loads to study their nonlinear behavior using a newly developed test method that maintained equal rotations at the two ends of the coupling beam specimen and allowed for local deformations at the beam-wall joints. By conducting the tests under displacement control, the post-peak behavior and complete load-deflection curves of the coupling beams were obtained for investigation. It was found that after the appearance of flexural and shear cracks, a deep coupling beam would gradually transform itself from an ordinary beam to a truss composed of diagonal concrete struts and longitudinal and transverse steel reinforcement bars. Moreover, in a deep coupling beam, the local deformations at the beam-wall joints could contribute significantly (up to the order of 50%) to the total deflection of the coupling beam, especially at the post-peak stage. Finally, although a coupling beam failing in shear would have a relatively low ductility ratio of only 5 or even lower, a coupling beam failing in flexure could have a relatively high ductility ratio of 10 or higher.

Evaluation on structural behaviors of prestressed composite beams using external prestressing member

  • Ahn, Jin-Hee;Jung, Chi-Young;Kim, Sang-Hyo
    • Structural Engineering and Mechanics
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    • 제34권2호
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    • pp.247-275
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    • 2010
  • In this study, experimental, numerical, and analytical approaches were carried out to evaluate the behavior and prestressing effect of prestressed composite beam by external tendon and cover plate. Behavior of prestressed composite beam, load-carrying capacity, effects of prestressing, and ultimate strength were estimated. The contribution of the section increase of the prestressing method using tendon was less than the prestressing method using cover plate. In accordance with numerical and analytical approaches, the ultimate strength of the prestressed composite beam is shown to be the same value because strength is determined according to the plastic resistance moment and the plastic neutral axis; however, both plastic resistance moment and neutral axis are not affected by prestressing force but affected by sectional stiffness of the prestressing member. Based on these approaches, we concluded that the prestressing method using tendon can be useful in applications without an increase in self-weight, and the prestressing method using high-strength cover plate can be applied to reduce the deflection of the composite beam. The prestressing method using high-strength cover plate can also be used to induce prestress of the composite beam in the case of a large deflection due to a smaller sectional stiffness of the composite beam.

A semi-analytical procedure for cross section effect on the buckling and dynamic stability of composite imperfect truncated conical microbeam

  • Zhang, Peng;Gao, Yanan;Moradi, Zohre;Ali, Yasar Ameer;Khadimallah, Mohamed Amine
    • Steel and Composite Structures
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    • 제44권3호
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    • pp.371-388
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    • 2022
  • The present study tackles the problem of forced vibration of imperfect axially functionally graded shell structure with truncated conical geometry. The linear and nonlinear large-deflection of the structure are considered in the mathematical formulation using von-Kármán models. Modified coupled stress method and principle of minimum virtual work are employed in the modeling to obtain the final governing equations. In addition, formulations of classical elasticity theory are also presented. Different functions, including the linear, convex, and exponential cross-section shapes, are considered in the grading material modeling along the thickness direction. The grading properties of the material are a direct result of the porosity change in the thickness direction. Vibration responses of the structure are calculated using the semi-analytical method of a couple of homotopy perturbation methods (HPM) and the generalized differential quadrature method (GDQM). Contradicting effects of small-scale, porosity, and volume fraction parameters on the nonlinear amplitude, frequency ratio, dynamic deflection, resonance frequency, and natural frequency are observed for shell structure under various boundary conditions.

On nonlinear deflection analysis and dynamic response of sandwich plates based on a numerical method

  • Yong Huang;Zengshui Liu;Shihan Ma;Sining Li;Rui Yu
    • Steel and Composite Structures
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    • 제47권1호
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    • pp.79-90
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    • 2023
  • Nonlinear forced vibration properties of three-layered plates containing graphene platelets (GPL) filled skins and an auxetic core have been inquired within the present paper. Owning reduced weight as well as reduced stiffness, rectangle-shaped auxetic cores have been frequently made from novel techniques such as additive manufacturing. Here, the rectangle shape core is amplified via the graphene-filled layers knowing that the layers possess uniform and linear graphene gradations. The rectangle shape core has the equivalent material specifications pursuant to relative density value. The sandwich plate is formulated pursuant to Kirchhoff plate theory while a numerical trend has been represented to discretize the plate equations. Next, an analytical trend has been performed to establish the deflection-frequency plots. Large deflections, core density and GPL amplification have showed remarkable impacts on dynamic response of three-layered plates.

냉간 압연 공정에 의한 두께 $36{\mu}m$ 동극박 제조 공정 해석 (Fabrication of copper thin foils with 36 microns by cold rolling)

  • 이상호;김병민
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 춘계학술대회 논문집
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    • pp.413-416
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    • 2007
  • In general, by means of the electrodepositing technique, a copper foil sample was prepared with a high purity and a high density. But the mechanical properties of the electrodepositing copper foil was lower than it's the rolling copper foil. However, the production of copper foil with approximately 36 microns thick in rolling process was very difficult. This paper describes the outline of the high accuracy cold rolling in 6 high mill which was developed for the purpose of rolling very thin accurate gauge copper foil(36 micron thick), and give several rolling characteristic of 600 mm wide copper foil. a) Large strain can be accumulated pass by pass in industrial multi-pass rolling processing to overcome large critical strain for thickness accuracy through optimization of rolling schedule. b) Also, permissible tension for rolling 0.45 $\sim$ 0.036 mm thick copper strip stably in accordance with the each pass work had been established by FEM simulation results. c) During the plate rolling process, considerable values of the forces of material pressure on the tool occur. These pressures cause the elastic deformation of the roll, thus changing the shape of the deformation region. A numerical simulation of roll deflection during cold rolling is presented in the paper. d) The proposed pass schedule can roll very thin copper foil of 36 micron thickness to a tolerance of ${\pm}1$ microns. The validity of simulated results was verified into rolling experiments on the copper foil.

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자유후류기법을 이용한 무힌지 로터 시스템의 정지비행시 정적 공탄성 해석 (Static Aeroelastic Analysis of Hingeless Rotor System in Hover Using Free-Wake Method)

  • 유승재;임인규;이인;김도형;김덕관
    • 한국항공우주학회지
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    • 제36권2호
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    • pp.156-162
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    • 2008
  • 본 연구에서는 자유후류기법을 이용하여 복합재 무힌지 로터 블레이드에 대한 정적 공탄성 해석을 수행하였다. 1차원 보의 거동을 해석하기 위하여 대변형 보 이론이 적용되었다. 또한, 복합재 블레이드의 단면 해석을 위하여 이방성 보 이론이 적용되었다. 공탄성 해석에 필요한 공력 하중들은 와류격자법(VLM)에 기초한 3차원 공기력 모델을 통하여 계산되었다. 이때, 정지비행시의 후류는 순차적 시간 적분 자유후류법을 통하여 묘사되었다. 복합재 무힌지 로터 블레이드의 정적 변형에 대한 해석 결과를 2차원 준정상 공기력과 경험후류기법을 통한 해석 결과들과 비교하여 살펴보았다. 결과적으로, 정지비행시 후류 효과에 의해 정적 변형의 결과가 달라짐을 확인하였다.

콘크리트 충진 FRP 거더의 전단재하 실험에 관한 연구 (A Study on Shear Strength Test for FRP Girder of Filled Concrete)

  • 곽계환;장화섭;김우종;김회옥
    • 한국전산구조공학회논문집
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    • 제21권4호
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    • pp.365-373
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    • 2008
  • 섬유복합재료(Fiber Reinforced Polymer, FRP)는 경량성, 높은 설계기준강도, 비전기 비자성 및 내부식성의 특징 등으로 인하여 최근 건설분야에서 많은 연구가 진행되고 있다. 그 중 GFRP(Glass Fiber Reinforced Polymer)는 가격 경쟁성에서 우수하여 일반적으로 많이 사용되고 있다. 그러나 GFRP는 상대적으로 낮은 탄성계수를 가지고 있어 처짐이 과대하게 발생함으로 구조부재 단면으로서 활용되기 위해서는 단면이 커야하며, 설계시 사용하중에 의한 처짐 제한에 대한 검토를 실시해야 한다. 이에 본 연구에서는 언급된 기술적인 문제점을 해결하기 위하여 대형 단면의 적용이 가능하도록 모듈형식의 단면을 제안하였다. 그리고 FRP의 낮은 강성을 확보하군 위하여 콘크리트를 충진하는 새로운 FRP+콘크리트 합성 거더 형상을 개발하였다. 개발된 FRP)콘크리트 합성 거더의 전단지간비와 콘크리트 충진 여부에 따른 전단강도 및 처짐, 중립축 변화를 확인하고자 전단실험을 실시하였다.

티(Tee)형(型) 보강재로 보강된 곡판의 붕괴모드에 대한 검토 (Investigation for Collapse Mode of Stiffened Curved Plate with Tee Shaped Stiffeners)

  • 오영철;김경탁;고재용
    • 해양환경안전학회지
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    • 제17권3호
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    • pp.295-300
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    • 2011
  • 선박은 상자형태 구조로 구성되어 있으며 선박의 선 수미, 선저만곡부, 갑판 등에 주로 사용하고 있다. 이런 구조는 박판구조이며 1차 지지부재로 사용된다. 평판구조와 비교하였을 때 상이한 거동을 보이며 일반적으로 압축하중을 받을 경우 곡률변화에 따라 다른 좌굴 및 최종 강도 경향을 나타냈다. 따라서 본 논문에서는 압축하중을 받고 있는 보강곡판인 1/2+1+1/2 bay 모델에 대하여 비선형유한요소해석을 수행하였으며 매개변수 영향은 곡률변화뿐만 아니라 세장비, 웨브높이/두께 등을 고려하여 해석모델에 대한 붕괴모드에 대해 검토하였다.

Assessment of geometric nonlinear behavior in composite beams with partial shear interaction

  • Jie Wen;Abdul Hamid Sheikh;Md. Alhaz Uddin;A.B.M. Saiful Islam;Md. Arifuzzaman
    • Steel and Composite Structures
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    • 제48권6호
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    • pp.693-708
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    • 2023
  • Composite beams, two materials joined together, have become more common in structural engineering over the past few decades because they have better mechanical and structural properties. The shear connectors between their layers exhibit some deformability with finite stiffness, resulting in interfacial shear slip, a phenomenon known as partial shear interaction. Such a partial shear interaction contributes significantly to the composite beams. To provide precise predictions of the geometric nonlinear behavior shown by two-layered composite beams with interfacial shear slips, a robust analytical model has been developed that incorporates the influence of significant displacements. The application of a higher-order beam theory to the two material layers results in a third-order adjustment of the longitudinal displacement within each layer along the depth of the beam. Deformable shear connectors are employed at the interface to represent the partial shear interaction by means of a sequence of shear connectors that are evenly distributed throughout the beam's length. The Von-Karman theory of large deflection incorporates geometric nonlinearity into the governing equations, which are then solved analytically using the Navier solution technique. Suggested model exhibits a notable level of agreement with published findings, and numerical outputs derived from finite element (FE) model. Large displacement substantially reduces deflection, interfacial shear slip, and stress values. Geometric nonlinearity has a significant impact on beams with larger span-to-depth ratio and a greater degree of shear connector deformability. Potentially, the analytical model can accurately predict the geometric nonlinear responses of composite beams. The model has a high degree of generality, which might aid in the numerical solution of composite beams with varying configurations and shear criteria.