• Title/Summary/Keyword: 단면 2차 모멘트

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Deflection Estimation of Reinforced Concrete Beams Derived from Crack Widths (균열폭을 통한 철근콘크리트 보의 처짐 추정)

  • Kang, Ju-Oh;Kim, Kang-Su;Lee, Deuck-Hang;Hwang, Jin-Ha;Im, Ju-Hyeuk;Lee, Jung-Yeon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.157-158
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    • 2010
  • Based on the relation between cracks and deflection in a RC beam, this study proposed a method to estimate the deflection of RC beams directly from the condition of cracks not using the actual loads acting on the member. The deflections of members were successfully estimated by the proposed method, which was also easy to apply compared to the existing methods.

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A Study on the Static Rigidity of the End Mill (엔드밀의 정적 강성에 관한 연구)

  • 이상규;고성림
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.9-14
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    • 1996
  • The deflection of an end mill is very important in machining process and cutting simulation because it affects directly workpiece accuracy, cutting force, and chattering. In this study, the deflection of the end mill was studied both experimentally and by using finite element analysis. And the moment of inertia of radial cross sections of tile helical end mill is calculated for the determination of the relation between cross section and rigidity of tile tools. Using tile Bernoulli-Euler beam and and the concept of equivalent diameter, a deflection model is established, which includes most influence from tool geomety parameters. It was found that helix angle attenuates the rigidity of the end mill.

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The equivalent second moment of area for the symmetrically tapered compression member (대칭형으로 taper진 압축재의 등가 단면2차모멘트)

  • 김상조;민영숙;김순철;이수곤
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.04a
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    • pp.291-298
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    • 2001
  • When the compression members have the variable cross sections along their member axes, the determination of the elastic critical loads by classical methods becomes impossible and if possible involves complicated calculation only to obtain the approximate values of critical load. In this paper the elastic critical load coefficients of the tapered members with simply supported ends were determined by finite element method. And then the results were represented by simple algebraic equations of two parameters, a( =taper parameter) and m ( = sectional property parameter). One the basis of algebraic equations, the equivalent moment of inertia concept originally proposed by Bleich for a spesific case, are extended to the general cases.

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Relationship between crack width and deflection in reinforced concrete beam (철근콘크리트 보의 균열폭과 처짐 관계)

  • Lee, Seung-Bae;Kim, Kang-Su;Kang, Ju-Oh;Choi, Jin-Young;Park, Mi-Yeung;Kim, Sang-Sik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.293-296
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    • 2008
  • The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete (RC) structures, and the concept of the effective moment of inertia has been generally used for its estimation. However, the actual service load applied on an existing RC beam may not be easily obtained, for which the estimation of beam deflection by existing methods can be difficult work. Therefore, based on the close relationships between cracks and deflection in a RC beam, this study proposed a method to estimate the deflection of RC beams directly from the condition of cracks not using the actual loads acting on the member as its input data. The proposed method extensively utilized the relationships among sums of crack widths, average strains, and curvatures, and modification factors obtained from regression analysis were also introduced to improve its accuracy. The deflections of members were successfully estimated by the proposed method independent from applied loads, which was also easy to apply compared to the existing methods based on the effective moment of inertia. This new method, however, has limitations in its applicability in that it is less accurate than the existing methods because the magnitude of acting load is not involved in the estimation process of member deflection, and that it requires the measurement of crack widths along the whole length of a member.

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An Experimental Study on the Flexural Stiffness and Plastic Hinge Ratation Capacity of Reinforced High Performance Concrete Beams (고성능 철근콘크리트 보의 휨강성 및 소성힌지의 회전능력에 관한 실험적 연구)

  • 고만영;김상우;김용부
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.93-100
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    • 1998
  • This paper presents a study on the flexural stiffness, plastic hinge length and plastic hinge rotation capacity of reinforced high performance concrete beams. 15 beams with different strength of concrete, reinforcement ratio and the pattern of loadings were tested. From the test results of reinforced normal strength concrete beams and reinforced high performance concrete beams with the concrete which has cylinder compressive strength of 700kg/${cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. It is found that an extreme fiber concrete compressive strain of ${\varepsilon}_{cu}=0.0047$ may be used in ultimate curvature computations of reinforced high performance concrete beams. An empirical equation is proposed to estimate the effective moment of inertia. length and rotation capacity of plastic hinge of simply supported reinforced high performance concrete beams. The estimated deflections using this equation agree well with the experimental values.

Experimental Study on Deflection Evaluation of KCI specification and Eurocode 2 (콘크리트 구조 설계기준과 Eurocode 2의 처짐 산정에 관한 실험적 고찰)

  • Lee, In-Ju;Kim, Tae-Wan;Oh, Seok-Mim;Kim, Jun-Won;Park, Sun-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.141-144
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    • 2008
  • Deflection in terms of serviceability of reinforced concrete structures is considered as one of significant factor. Domestic concrete specification offers a procedure to evaluate deflection using effective moment of inertia at cracked section, which has been known as Branson's equation in ACI. Branson's equation was derived from statistical analysis of maximum deflection of flexural members, but is somewhat weak in no reflection of bond characteristics between reinforced bars and concrete, such as tension stiffening effect. Therefore, present code creates difference from actual deflection. In this study, experiments about deflection of RC beams was completed to compare domestic standard and Eurocode 2, which calculates deflection considering tension stiffening effect. Four RC beams were built and tested, and initial modulus of elasticity and tensile strength of concrete used in the test was calculated by each design standard.

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Development of a Design System for a Cable Tray (케이블 트레이 설계시스템 개발)

  • Choi, Du-Soon;Choi, WooSeok
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.4
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    • pp.89-96
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    • 2017
  • A cable tray is a structure made of metal or a non-combustible material that supports cables in the electrical wiring of buildings. Cable trays should be developed to meet the various requirements of the construction site. In this study, a design system was developed to calculate the maximum support load and the maximum deflection according to the cross-sectional shape of the cable tray. The cross-sections of cable trays were modeled by combining linear and arc elements, and cross-sectional characteristics such as the 2nd moment of area were calculated. The distributed load and the concentrated load were applied to the cable tray using the Euler beam theory, and then the deflection profiles and maximum stress were calculated. To verify the developed system, deflection distributions and maximum stresses for two types of cable trays were calculated and compared. The maximum deflection and maximum stress errors calculated from the developed system were found to be less than 4% compared with numerical analysis results.

Analysis of Lodging Related Characteristics in Rice Plants (벼 도복에 관여하는 형질 분석)

  • 임준택;이홍재;조광석;송동석
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.37 no.1
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    • pp.78-85
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    • 1992
  • This experiment was carried out to investigate the heritabilities, phenotypic correlation, genetic correlation and path-coefficients for desirable characters on the lodging related traits. Characters, that had high relation degree with field lodging degree, were rice-straw length, Wl /P, W/I, Wl /d, L, Wl / A, W/l, P, W $s^2$/ $l^4$ etc. Breaking strength appear negative correlation having an intention to field lodging. The second inertia moment of culm diameter trunk (branch), cross section area, rice-straw thickness and trunk cross section didn't appear negative coefficient with field lodging. It is considered that rice-straw length, leaf dry weight and lodging index, because of high heritability, become selection index of characters for breeding. In direct, indirect effect, and right rice-straw wall thickness appear largest( $P_{7y}$=0.6904), the next is the order of leaf dry weight( $P_{3y}$=0.2848), root dry weight ( $P_{1y}$=0.2658), culm diameter ( $P_{6y}$=-0.2280), and negative relation appear the order of rice-straw length ( $P_{5y}$=-0.9640) and stem dry weight( $P_{2y}$=-0.7072), therefore, the smaller culm length and stem dry weight, the stronger to lodging. to lodging.

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Strength and Vibration Characteristic of Aluminum Honeycomb Sandwich Panel Structure (알루미늄 하니콤 샌드위치 패널구조의 강도 및 진동특성)

  • 배동명;최철은
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.38 no.2
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    • pp.101-109
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    • 2002
  • The aluminum honeycomb sandwich panel (AHSP) structure not only have high flexural rigidity and strength per density but also excellence in vibration and noise properties. The AHSP structure are very useful for railway, airplane and high speed ship which need lighter-weighted and more strengthened elements. In this paper, from comparison the AHSP with the equivalent aluminum single plate (EASP) structure on the result of analysis, it was shown that the AHSP is S times lighter weight to the same stiffness than the EASP. And the AHSP structure have high bending rigidity and small shear rigidity in the direction of the thickness. Also, to the characteristics of vibration for the AHSP and EASP, which the stiffness is larger than the EASP, are higher than EASP.

Approximate Method to Estimate Member Forces in the Column of a Rigid Frame (강접골조 기둥의 부재력 산정을 위한 근사해석법)

  • Kim, Young-Chan;Yoon, Tae-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.7
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    • pp.4611-4617
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    • 2014
  • This paper proposes an approximate method to estimate member forces of columns in a rigid frame. One of the conventional methods, Cantilever Method assumes the midpoint of a column as a hinge and linear distribution of axial stresses regarding the centroid of the column areas. As a result, it shows erroneous results compared to those of matrix analysis of two frames. In this study, a new method is proposed to estimate the member forces in columns and location of hinges in columns, which can be adopted easily by a practicing engineer, and numerical examples showed improved results compared to conventional methods.