• 제목/요약/키워드: Simple Beam

검색결과 1,068건 처리시간 0.022초

A practical model for simulating nonlinear behaviour of FRP strengthened RC beam-column joints

  • Shayanfar, Javad;Bengar, Habib Akbarzadeh
    • Steel and Composite Structures
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    • 제27권1호
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    • pp.49-74
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    • 2018
  • Generally, beam-column joints are taken into account as rigid in assessment of seismic performance of reinforced concrete (RC) structures. Experimental and numerical studies have proved that ignoring nonlinearities in the joint core might crucially affect seismic performance of RC structures. On the other hand, to improve seismic behaviour of such structures, several strengthening techniques of beam-column joints have been studied and adopted in practical applications. Among these strengthening techniques, the application of FRP materials has extensively increased, especially in case of exterior RC beam-column joints. In current paper, to simulate the inelastic response in the core of RC beam-column joints strengthened by FRP sheets, a practical joint model has been proposed so that the effect of FRP sheets on characteristics of an RC joint were considered in principal tensile stress-joint rotation relations. To determine these relations, a combination of experimental results and a mechanically-based model has been developed. To verify the proposed model, it was applied to experimental specimens available in the literature. Results revealed that the model could predict inelastic response of as-built and FRP strengthened joints with reasonable precision. The simple analytic procedure and the use of experimentally computed parameters would make the model sufficiently suitable for practical applications.

구조연성을 고려한 복합재료 상자형 보의 강성계수 예측에 관한 연구 (Calculation of Stiffnesses Properties for Composite Box-Beams with Elastic Couplings)

  • 정성남;동경민
    • Composites Research
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    • 제14권6호
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    • pp.9-15
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    • 2001
  • 본 연구에서는 복합재료로 만들어진 박판의 상자형 보에 대만 선형 정적해석을 수행하였다. 복합재료 보의 해석을 위해서 혼합 보 이론을 적용하였으며, 상자형 단면의 벽에 대해 설정이 가능한 여러 가지 구성방정식을 고려할 수 있도록 하였다. 굽힘-비틀림 혹은 인장-비틀림 연성을 갖는 단순한 적층 형상의 복합재료 강자형 보를 예로 들어 보의 정적 거동에 미치는 복합재료의 연성효과를 고찰하였다. 본 해석결과의 타당성을 검증하기 위만 방편으로 상용 구조해석 프로그램을 이용한 정밀 유한요소 구조해석을 수행하였다. 혼합 보 이론을 이용하여 복합재료 상자형 보에 대한 단면상수 등을 해석적으로 결정하였으며, 적절한 구성방정식의 설정 여부가 최종적인 해의 정확도를 결정하는 중요한 요소임을 보였다.

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Simplified analytical model for flexural response of external R.C. frames with smooth rebars

  • Campione, Giuseppe;Cannella, Francesco;Cavaleri, Liborio;Monaco, Alessia
    • Structural Engineering and Mechanics
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    • 제66권4호
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    • pp.531-542
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    • 2018
  • In this paper an analytical model in a closed form able to reproduce the monotonic flexural response of external RC beam-column joints with smooth rebars is presented. The column is subjected to a constant vertical load and the beam to a monotonically increasing lateral force applied at the tip. The model is based on the flexural behavior of the beam and the column determined adopting a concentrated plasticity hinge model including slippage of the main reinforcing bars of the beam. A simplified bilinear moment-axial force domain is assumed to derive the ultimate moment associated with the design axial force. For the joint, a simple truss model is adopted to predict shear strength and panel distortion. Experimental data recently given in the literature referring to the load-deflection response of external RC joints with smooth rebars are utilized to validate the model, showing good agreement. Finally, the proposed model can be considered a useful instrument for preliminary static verification of existing external RC beam-column joints with smooth rebars for both strength and ductility verification.

저에너지 대면적 전자빔 발생장치 개발에 관한 연구 (A Study on the Low-energy Large-aperture Electron Beam Generator)

  • 조주현;최영욱;이홍식;임근희;우성훈;이광식
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제48권12호
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    • pp.785-790
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    • 1999
  • This research has been carried out to develop a low-energy large-aperture pulsed electron beam generator (LELA), 200keV 1A, for industrial applications. One of the most important feature of this electron beam generator is large electron beam cross section of $190cm^2$. Low energy electron beam generators have been used for water cleaning, flue gas cleaning, and pasteurization, etc. In these applications the cross sectionof the e-beam is related to reaction efficiency. Another important feature of this LELA EB generator is easy maintenance because of its simple structure and relatively low vacuum operation compared to the conventional EB generators. The conventional EB generators need to be scanned because the small cross section thermal electron emitters are used in the conventional EB generators which have small EB cross section. In this research, we use the secondary electrons generated by ion bombardment on the HV cathode surface as a electron source. Therefore we can make any shape of EB cross section without scanning.

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이동질량을 고려한 단순지지된 교량의 진동수 및 공진현상 분석 (The Effect of Moving Mass on Resonance Phenomenon and Natural Frequency of a Simply Supported Beam)

  • 민동주;정명락;박성민;김문영
    • 한국소음진동공학회논문집
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    • 제26권1호
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    • pp.27-38
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    • 2016
  • The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

내력상태계수 도입을 통한 RC보의 전단강도분석 (Shear Strength Incorporated with Internal Force State Factor in RC Slender Beams)

  • 정제평;김희정;김우
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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    • pp.912-917
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    • 2003
  • In this paper a new truss modeling technique for describing the beam shear resistance mechanism is proposed based on the reinterpretation of the well-known relationship between shear and the rate of change of bending moment in a reinforced concrete beam subjected to combined shear and moment loads. The core of the model is that a new perspective on the shear resistance can be gained by viewing the internal stress filed in terms of the superposition of two base components of shear resistance; arch action and beam action. The arch action can be described as a simple tied-arch which is consisted of a curved compression chord and a tension tie of the longitudinal steel, while the beam action between the two chords can be modeled as a membrane shearing element with forming a smeared truss action. The compatibility of deformation associated to the two action is taken into account by employing an experimental factor or internal state force factor a. Then the base equation of V=dM/dx is numerically duplicated. The new model was examined by the 362 experimental results. The shear strength predicted by the internal force state factor a show better correlation with the tested values than the present shear design.

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열확산도 측정을 위한 광열 신기루 기법 개발 (Development of Photothermal Mirage Technique for Measuring Thermal Diffusivity)

  • 최선락;이주철;김동식
    • 대한기계학회논문집B
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    • 제27권9호
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    • pp.1220-1228
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    • 2003
  • The mirage technique is proved to be powerful in measuring the thermal diffusivity of materials. In particular, its contactless nature makes it suitable for delicate samples and microscale structures. In this study, thermal-wave-coupling method is developed in a general form for both thermally thin and thick samples. In the suggested measuring scheme, the probe beam can be positioned close to the pump beam and the absolute position need not be measured. Therefore the new scheme provides a relatively simple yet effective way to determine the thermal diffusivity of thermally thick samples. Thermal diffusivities of bulk samples like Ni and Al were measured and the characteristics of mirage signal for a thin film were observed by using the mirage experimental setup. The apparent thermal diffusivity was measured by varying such parameters as probe beam height, size of pump beam, power of pump beam, and surface condition of sample. From the practical standpoint, it is shown that the size of the pump beam is the most important factor for accurate thermaldiffusivity measurement. Experiments using thin-film samples show that the thermal diffusivity of a substrate covered with thin film can be measured by photothermal mirage signals.

유한요소법을 이용한 이동질량 하에 크랙을 갖는 티모센코 보의 동특성 연구 (Dynamic Analysis of the Cracked Timoshenko Beam under a Moving Mass using Finite Element Method)

  • 강환준;이시복;홍금식;전승민
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2004년도 학술대회지
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    • pp.271-276
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    • 2004
  • In this paper. dynamic behavior of the cracked beam under a moving mass is presented using the finite element method (FEM). Model accuracy is improved with the following consideration: (1) FE model with Timoshenko beam element (2) Additional flexibility matrix due to crack presence (3) Interaction forces between the moving mass and supported beam. The Timoshenko bean model with a two-node finite element is constructed based on Guyan condensation that leads to the results of classical formulations. but in a simple and systematic manner. The cracked section is represented by local flexibility matrix connecting two unchanged beam segments and the crack as modeled a massless rotational spring. The inertia force due to the moving mass is also involved with gravity force equivalent to a moving load. The numerical tests for various mass levels. crack sizes. locations and boundary conditions were performed.

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보 요소와 비선형 스프링 특성을 이용한 버스 전복 해석 (Rollover Analysis of a Bus using Beam Element and Nonlinear Spring Characteristics)

  • 박수진;유완석;권연주;김진배
    • 한국자동차공학회논문집
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    • 제15권1호
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    • pp.56-63
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    • 2007
  • In case of bus rollover, the body structure of the bus should be designed to ensure the survival space for passengers. So, this study focuses on evaluating rollover strength through a computer simulation using the commercial code, LS-DYNA3D at the initial stage of vehicle development. For this study, section structure was modeled using a simple beam element, and impact boundary conditions required by ECE(Economic Commission for Europe) regulation No.66 were applied. In order to confirm the validity of the beam element bus model, the results compared with the test results and shell element bus model. The analysis errors from beam element bus model are due to the difference in strain energy of joint area between beam and shell model. In this study, a method for the joint modeling was suggested by using nonlinear springs to which the collapse mechanisms were applied.

Winkler 지반상에 놓인 강성보의 해석 (Analytic Study on Rigid Beam Resting on Winkler Foundation)

  • 이승현;권오순;장인성
    • 한국산학기술학회논문지
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    • 제12권11호
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    • pp.5300-5305
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    • 2011
  • Winkler 지반과 2변수 Winkler 지반상에 놓인 강성보에 집중하중과 모멘트가 작용하는 경우에 대해 강성보에 발생하는 변위, 접촉압력, 모멘트를 유도하여 보았다. Winkler 지반상의 강성보에 발생하는 모멘트의 유도결과로 부터 강성보를 따르는 모멘트분포는 스프링 상수와 무관하게 나타남을 알 수 있었고 스프링 상수가 선형인 경우가 일정한 경우에 비해 모멘트값이 크게 계산되었다. 간단한 계산을 통해 볼 때 2변수 Winkler 지반에 놓인 강성보에 발생하는 최대 휨모멘트가 Winkler 지반에 놓인 강성보에 발생하는 그것에 비해 크게 계산되었다.