Loading [MathJax]/jax/output/CommonHTML/jax.js
  • Title/Summary/Keyword: 편심도

Search Result 615, Processing Time 0.03 seconds

Exact Dynamic Stiffness Matrix of Nonsymmetric Thin-walled Beams Subjected to Eccentrically Axial Forces (편심축하중을 받는 비대칭 박벽보의 엄밀한 동적강도행렬)

  • Kim, Moon Young;Yun, Hee Taek
    • Journal of Korean Society of Steel Construction
    • /
    • v.13 no.6
    • /
    • pp.703-713
    • /
    • 2001
  • Derivation procedures of exact dynamic stiffness matrices of thin-walled straight beams subjected to eccentrically axial forces are rigorously presented for the spatial free vibration analysis. An exact dynamic stiffness matrix is established from governing equations for a uniform beam element with nonsymmetric thin-walled cross section. First this numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. Thus, the displacement functions of displacement parameters are exactly derived and finally exact stiffness matrices are determined using element force-displacement relationships. The natural frequencies of nonsymmetric thin-walled straight beams are evaluated and compared with analytical solutions or results by thin-walled beam element using the cubic Hermitian polynomials and ABAQU's shell elements in order to demonstrate the validity of this study.

  • PDF

Air Curtain Nozzle Design for Uniform Jet Expulsion (균일한 제트 분출을 위한 에어커튼 노즐 설계)

  • Park, Won-Hee;Chang, Hee-Chul
    • Fire Science and Engineering
    • /
    • v.30 no.4
    • /
    • pp.39-45
    • /
    • 2016
  • The optimal design of an air curtain nozzle installed at exits, such as fire doors, was determined in order to block the flow of smoke into safe zones. Smoke is the greatest cause of loss of life during the fire. To block the flow of smoke, the airflow must be expelled uniformly without eccentricity from the slits in the air curtain nozzle installed on the upper part of the opening. In order to accomplish this, factors such as air inflow volume, shape of the internal slits, and thickness of the external slits were considered as variables in this study, and a numerical analysis was performed under various conditions. This led to the selection of a final shape which led to the finalization of a design shape. The final shape was manufactured as a prototype and the results were compared and verified with the results of the numerical analysis. The relative error of the numerical analysis results was less than 1%, and the average speed of all the slits was tested, exhibiting a highly consistent tendency.

Torsional Behaviour of Concrete Filled Circular Steel Tube Column Considering Confinement Effect (구속효과를 고려한 콘크리트 충전 원형강관 기둥의 비틀림 거동)

  • Yun, Bok Hee;Lee, Eun Taik;Park, Ji Young;Jang, Kyong Ho
    • Journal of Korean Society of Steel Construction
    • /
    • v.16 no.5 s.72
    • /
    • pp.529-541
    • /
    • 2004
  • Concrete filled steel tube structures were recently used in constructing high-rise buildings due to their effectiveness. Studies on concrete filled steel tubes have been focused on the experiments of uni-axial compression and bending and eccentric compression. There were also a few studies that investigated CFT member behavior under combined compression and torsion. The behavior of a circular CFT column under combined torsion and compression was theoretically investigated, considering the confinement of steel tubes on the concrete, the softening of the concrete, and the spiral effect, which were the dominant factors that influenced compression and torsion strength. The biaxial stress effects due to diagonal cracking were also taken into account. By applying those factors to compatibility and equilibrium conditions, the basic equation was derived, and the equation could be used to incorporate the torsional behavior of the entire loading history of the CFT member.

Effects of Axial Misalignments on the Torque Specimens Using Finite Element Analysis (유한요소해석기법을 이용한 토크 시편의 축 오열 영향 분석)

  • Kim, Ju-Hee;Kim, Yun-Jae;Huh, Yong-Hak
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.35 no.11
    • /
    • pp.1461-1469
    • /
    • 2011
  • Using three-dimensional (3-D) FE analyses, this paper provides a method for analyzing the effects on stresses and strains produced by angular and concentric misalignment of a test specimen for a torsion test. To quantitativele compare of the FE results, the average bending strain for the angular, concentric, and combined misalignment was proposed. To verify the effects of axial misalignment of the test specimens, we used both circular and tubular specimens. From the FE results, we proposed general predictions for the effects caused by the various types of axial misalignment and its direction. In addition, we confirmed the effect of initial yielding moment based on the initial yielding condition for axial misalignment of specimens in torsion tests.

Flexural Behavior Characteristics of Steel I-Beam Strengthened by the Post-tensioning Method on the Field Experiment (현장실험을 통한 외부 후긴장 Steel I-Beam의 휨 거동 특성)

  • Cho, Doo-Yong;Park, Dae-Yul;Park, Sun-Kyu
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.6 no.3
    • /
    • pp.151-158
    • /
    • 2002
  • Recently, the externally prestressed unbonded steel I-beam bridges have been increasingly built. The mechanical behavior of prestressed steel I-beams which are with external unbonded tendon is different from that of normal bonded PSC beams in a point of that the slip of tendons at deviators and the change of tendon eccentricity occurs, when external loads are applied in external unbonded steel I-beams. The concept of prestressing steel structures has not been widely considered, in spite of long and successful history of prestressing concrete members. In this study, The field experiment on prestressed steel I-beams has been performed in the various aspects of prestressed I-beam including the tend on type and profile.

Design Strength of Non-symmetric Composite Column for Modular Unit Frames (모듈러 유닛 골조용 비대칭 합성기둥의 설계강도)

  • Park, Keum-Sung;Lee, Sang-Sup;Moon, Ji-Ho
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.22 no.5
    • /
    • pp.101-109
    • /
    • 2018
  • Modular structural systems have been used increasingly for low- and mid-rise structures such as school and apartment buildings. Studies have recently been conducted on the application of the modular structural system to high-rise buildings. To provide sufficient resistances and economical construction for the high-rise modular structural system, a composite unit modular structure was proposed. In this study, the strength of the non-symmetric composite column for the proposed composite unit modular structure was investigated through a series of tests. The experimental study focused on the effect of the slenderness of the column, eccentricity, and through bars on the strength of such a column. Design equations for the non-symmetric column for a modular unit structure were also proposed. From the results, it was found that the proposed design equations provide reasonable strength prediction of the non-symmetric composite column for the modular unit structure.

Study on Evaluation Method of Flow Characteristics in Steady Flow Bench(5)-Effect of Evaluation Position (정상유동 장치에서 유동 특성 평가 방법에 대한 연구(5) - 평가위치의 영향)

  • Cho, Siehyung;Ohm, Inyong
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.25 no.2
    • /
    • pp.179-189
    • /
    • 2017
  • This paper is the fifth investigation on the methods of evaluating flow characteristics in a steady flow bench. In previous studies, several assumptions used in the steady flow bench were examined and it was concluded that the assumption of the solid rotation may lead to serious problems. In addition, though the velocity profiles were improved as the measuring position went downstream, the distributions were far from ideal regardless of the valve angle and evaluation position. The eccentricities were also not sufficiently small to disregard the effect on impulse swirl meter (ISM) measurement. Therefore, the effect of these distribution and eccentricity changes according to the positions needs to be analyzed to discuss the method of flow characteristics estimation. In this context, the effects of evaluation position on the steady flow characteristics were studied. For this purpose, the swirl coefficient and swirl ratio were assessed and compared via measurement of the conventional ISM and calculation based on the velocity by particle image velocimetry(PIV) from 1.75B, 1.75 times bore position apart from the cylinder head, to the 6.00B position. The results show that the swirl coefficients by ISM strictly decrease and the curves as a function of the valve lift become smooth and linear as the measuring position goes downstream. However, the values through the calculation based on the PIV are higher at the farther position due to the approach of the tangential velocity profile to ideal. In addition, there exists an offset effect between the velocity distribution and eccentricity in the low valve lift range when the coefficients are estimated based on the swirl center. Finally, the curve of the swirl ratio by ISM and by PIV evaluation as a function the measuring position intersect around 5.00B plane except at 26 valve angle.

Axial Strength of RC Columns Extracted from Existing Apartment Housings (기존 공동주택에서 채취한 철근콘크리트 기둥의 내력특성 평가 연구)

  • You, Young-Chan;Shin, Hyun-Seop;Choi, Ki-Sun;Lim, Byung-Ho;Kim, Keung-Hwan
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.14 no.6
    • /
    • pp.100-108
    • /
    • 2010
  • The axial strength of existing RC columns were experimentally investigated in this paper to understand the strength characteristics of existing structural members and to get a appropriate data in strengthening design of RC members in a remodelling construction. Ten RC columns were prepared by being cut and extracted directly from the demolition site of the apartment housings. Each column was tested under uniaxial loadings with different eccentricities in order to evaluate the axial strength of existing RC columns. From the test results, it was found that axial strength of all the specimens were at least 75% higher than those of the theoretical values required by current code. But member displacement ductility ratio were relatively low ranging from 2.12~5.86.

A Method for Calculation of Compressive Strength of a One-Sided Stiffened Plate (편면 보강판의 압축강도 해석을 위한 한 방법)

  • C.D. Jang;S.I. Seo
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.28 no.1
    • /
    • pp.117-124
    • /
    • 1991
  • In this paper, a method to overcome inefficiency of the finite element method in the calculation of compressive strength of one-sided stiffened plates, is proposed. In this method the collapse modes of stiffened plates are assumed as follows. a) Overall buckling Overall collapse b) Local buckling Overall collapse c) Local buckling Local collapse In each collapse mode, shape of deflection is assumed, and then elastic large deformation analysis based on the Rayleigh-Ritz method is carried out. One-sided stiffening effect is considered by taking into account of the moment due to eccentricity. Plastic analysis by assuming hinge lines is also carried out. The ultimate strength of a stiffened plate is obtained as the point of intersection of the elastic analysis curve and the plastic one. From this study, it is concluded that the angles between the plastic hinge lines in plastic collapse mode are determined as the ones which give the minimum collapse load, and these angles are different from the ones assumed in the previous studies. Minimum stiffness ratios can also be calculated. Calculated results according to this method show good agreements with the results by the finite element method.

  • PDF

Vibration Analysis of Separation Screen in a Recycling Plant of Moisturized Construction Wastes (고함수율의 건설폐기물 폐 토속에 포함된 이물질 선별을 위한 분리스크린의 진동해석)

  • Moon, Byung-Young;Bae, Hyo-Dong;Kwag, Kwang-Hun;Bae, Kee-Sun;Song, Ha-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.20 no.8
    • /
    • pp.526-533
    • /
    • 2008
  • In this study, theoretical super screen vibration analysis has been carried out to predict the dynamic characteristics of interactive waste particles. In order to approach these problems, it is necessary to have a fundamental understanding the screening process and the process of both the remaining and the passed material on a screen with several interacting screen planes based on Soldinger(1999) was discussed. Here, the vibrating screen is composed of three assemblies such as screen, wastes guide, and supported screen as shown in Fig. 1. This model is regarded vibrator as the system of screen fixed tilt plates. Then materials(or particles) of different size is to be separated by using the eccentric vibrator and classifying tilt plates. As well moisturized construction wastes is more efficient to separate than moisture-less it. In processing separate mechanism, the more materials is light, the more staying time is long. Thus much lighter construction wastes(wood, Styrofoam, etc) and heavier materials are separated by staying time delay in a super screen. The design results, separation screen were able to know that small and larger particles are conspicuous difference each motion character according to trajectory particles, and small particles raise the probability in classifying tilt plates.