• Title/Summary/Keyword: 단면 2차 모멘트

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Seismic Design of Rib-Reinforced RBS (Reduced Beam Section) Steel Moment Connections Based on Equivalent Strut Model (등가 스트럿 모델에 의한 리브 보강 RBS 철골모멘트접합부의 내진설계)

  • Lee, Cheol Ho
    • Journal of Korean Society of Steel Construction
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    • v.13 no.5
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    • pp.493-502
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    • 2001
  • This paper describes a seismic design procedure for rib-reinforced RBS(Reduced Beam Section) steel moment connections. Engineers often use rib plates to enhance seismic performance of steel moment connections. thinking that the 2nd moment of inertia is increased so that the tensile stress in the beam flange groove weld is reduced However the force transfer mechanism in the rib connections is completely different from that as predicted by the classical beam theory ; a clear diagonal strut action is present in the rib. By treating the rib as a strut the writer has recently proposed an equivalent strut model that could be used as the basis of a practical design procedure. In this paper the proposed equivalent strut model is briefly presented first. A step-by-step design procedure is then recommended based on the proposed model.

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Flexural Behavior of Concrete Beams Reinforced with CFRP rebars (CFRP Rebar로 보강한 콘크리트 보의 휨 거동)

  • Lee, Young-Hak;Won, Dong-Min;Kim, Min-Sook;Kim, Hee-Cheul
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.1
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    • pp.43-50
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    • 2010
  • To address the problems caused by the corrosion of steel rebar, active research has recently been carried out on members where fiber-reinforced polymer (FRP) is used in place of rebar. As FRP bar is highly brittle and has a low modulus of elasticity, further research is needed on the evaluation of serviceability, in other words on the deflection of flexural concrete members reinforced with FRP rebars. Taking the reinforcement ratio as a variable, this paper analyzes the flexural capacity of concrete beams reinforced with CFRP rebar. The test results of specimens reinforced with CFRP rebar show an increase in stiffness and resisting force along with an increase in the reinforcement ratio. A reinforcement ratio of about 1.3 is needed for the member reinforced with CFRP rebar to show same section property of a steel member. Through a comparison for the value of an effective moment of inertia, the equation suggested by Bischoff & Scanlon predicted values closest to the actual results.

Investigation on the Developing Turbulent Flow In a Curved Duct of Square Cross-Section Using a Low Reynolds Number Second Moment Turbulence Closure (2차모멘트 난류모형을 이용한 정사각 단면 곡덕트 내 발달하는 난류유동 변화에 대한 고찰)

  • Chun, Kun-Ho;Choi, Young-Don;Shin, Jong-Keun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.8
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    • pp.1063-1071
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    • 1999
  • Fine grid calculations are reported for the developing turbulent flow in a curved duct of square cross-section with a radius of curvature to hydraulic diameter ratio ${\delta}=Rc/D_H=3.357 $ and a bend angle of 720 deg. A sequence of modeling refinements is introduced; the replacement of wall function by a fine mesh across the sublayer and a low Reynolds number algebraic second moment closure up to the near wall sublayer in which the non-linear return to isotropy model and the cubic-quasi-isotropy model for the pressure strain are adopted; and the introduction of a multiple source model for the exact dissipation rate equation. Each refinement is shown to lead to an appreciable improvement in the agreement between measurement and computation.

Deflection Behavior of Concrete Members Reinforced with FRP Bars (FRP-보강근 콘크리트 부재의 처짐 거동)

  • Choi, Bong-Seob
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.2
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    • pp.936-943
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    • 2011
  • The effective moment of inertia revising the expression proposed by Branson has been used in ACI 440.1R-06 design guide for calculating deflections of FRP-reinforced concrete members. However, its adequacy has been questioned by several researchers. The propose of this study is to provide fundamental data for the rational design of deflection by the comparison of the experimental results obtained from twelve specimens with rectangular section and nine specimens with T-shaped section to the theoretical results. As a result, it found that calculated results for specimens with rectangular section were underestimated comparing to test results, while calculated results for specimens with T-shaped section were overestimated comparing to test results.

Bending Moment Calculation Method and Optimum Element Size for Finite Element Analysis with Continuum Elements (연속체 요소를 사용한 유한요소해석의 휨 모멘트 계산 방법 및 최적의 요소 크기)

  • Heo, Ji-Hye;Kim, Han-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.1
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    • pp.9-16
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    • 2018
  • When designing a reinforced concrete member using nonlinear finite element analysis results, the bending moment at the critical section should be calculated. In this paper, a bending moment calculation method using the results of reinforced concrete finite element analysis(FEA) using continuum elements is presented and the optimum element size according to the order of the displacement function of the finite element is proposed. The bending moments calculated by integrating the stresses from the FEA are compared with the bending moments calculated using the static equilibrium conditions. In the method of integrating the stress, both the stress due to the reinforcing bar and the stress of the concrete are considered. In addition, various factors affecting the accuracy of the stresses calculated by the FEA were analyzed and the influence of the displacement function and the element size was verified. If the purpose of the analysis is to roughly observe the behavior of the members, it is appropriate to use the first order displacement function and the element size should be about 25% of the section height of the analytical model. When the bending moment of a member with high accuracy is required, it is suggested that the secondary displacement function be used and the element size be 12.5%.

Prediction of Deflection of Reinforced Concrete Beams due to Creep (크리프에 의한 철근콘크리트 보의 처짐 예측)

  • 이상순;김용빈;김진근;이수곤
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.253-260
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    • 1998
  • An approximate method for the calculation of creep deflections of reinforced concrete beams under sustained service loads is proposed. The position of neutral axis and strain and stress distribution of fully cracked section after creep is determined from the requirements of strain compatibility and equilibruim of a section and then the long-term flexural rigidity of fully cracked section is determined based on the new neutral axis. The long-term flexural rigidity of uncracked section at the level of the reinforcenment. The approach of calculating long-term effective flexural rigidity and defections is similar to the current American Concrete Institue procedure for calculating effecitve moment of inertia and short-term deflections. The accuracy of the analysis is verified by comparison with several experimental mesurements of beam deflectons. The result is good between the theotetical values and mesured valus.

Elastic Local Buckling of Orthotropic Open Section Compression Members with Asymmetric Edge Stiffeners (비대칭 연단보강재가 설치된 직교이방성 개방단면 압축재의 탄성국부좌굴)

  • 윤순종;정상균
    • Composites Research
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    • v.14 no.4
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    • pp.1-7
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    • 2001
  • This paper presents the results of an analytical investigation pertaining to the elastic local buckling behavior of asymmetric edge stiffened orthotropic open section structural member under uniform compression. The asymmetric edge stiffener is considered as a beam element neglecting its torsional rigidity. We suggested the analytical model of asymmetric edge stiffeners which is composed of a strip of flange plate, equal width of edge stiffener, and a plate attached at the flange end, and computed the moment of inertia of the stiffener about an axis through the centroid of the ensuing cross-section. Using the derived equation, the local buckling coefficients of asymmetrically edge stiffened orhtotropic I-section columns are predicted and the results are presented in a graphical form.

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Model on the Elastic Deflection of Temple of the Spectacle Frame (안경테 다리의 탄성변형에 관한 모델)

  • Kim, Dae-Soo
    • Journal of Korean Ophthalmic Optics Society
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    • v.12 no.1
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    • pp.41-51
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    • 2007
  • Differential equations and their solutions were formulated to describe the deflection of the tapered, nonuniform thickness and width's temple, clamped at one end while the perpendicular force is acting on the other end which is freely suspended. The model was derived based on laws of continuity at every point inside the elastic medium that the deflection, tangent slope, bending moment, shearing force must be continuous within the medium. The model is found to be in good agreement with measurements on the beta titanium temple with the correlation 0.992 and p=0.999(Chi test). Therefore it is possible to predict the effect of various temple parameters such as elastic modulus, thickness, width on the deflection of the temples being considered.

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An Analytical Study on the Structural Behavior of the Composite Slab with New-Shaped Deckplate (신형상의 합성용 데크플레이트를 사용한 합성슬래브의 구조적 거동에 관한 해석적 연구)

  • Moon, Tae Sup;Bae, Jong Woo
    • Journal of Korean Society of Steel Construction
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    • v.11 no.2 s.39
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    • pp.181-190
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    • 1999
  • The objective of this study is to investigate the structural behavior of the composite slabs with the new-shaped deckplate. In order to examine the deckplate as structural members, the composite slabs with new-shaped deckplate are compared and verified with the international design codes, and the simple inertia-moment equation of the composite slabs is suggested from the regression analysis of the results of the experiments. Besides, the finite element analysis was added on the purpose of the observation of structural behavior of the section items such as the Locking rib and the Dovetail. 36 experiments of composite slabs were performed with two new-type deckplates. And the finite-element analysis was performed by ABAQUS package with the function of the 3-dimension solid modeling.

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A study on shear behavior characteristics of RC hollow rectangular sectional piers (RC 중공구형단면 교각의 전단거동특성에 관한 연구)

  • Jung, Ji-Hwan;Sun, Chang-Ho;Kim, Ick-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.113-116
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    • 2008
  • In recent the construction of bridges having hollow sectional piers is gradually increasing since the hollow section is more effective than solid section in resistance against seismic load. It is, therefore, very important to understand the behavior of columns with hollow sections in seismic design. However, many past researches were concentrated only on the flexural deformability of them. In this study the shear characteristics of them have been studied with scale model tests. 7 models having different void and aspect ratios were designed and tested to investigate the effect of them on shear capacities. And then the validity of empirical equations to predict shear capacity was investigated compared with the test results. The test result 80 percent of the valid area of cross section should be adequate. And compared to the proposed four model the experimental shear capacities are in good agreement with the UCB.

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