• Title/Summary/Keyword: 편심도

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Experimental Study on the Behavior of Circular Steel Tube Columns using HSB600 Steel (HSB600 원형강관 기둥의 거동에 대한 실험적 연구)

  • Kim, Sun Hee;Choi, Young Hwan;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.24 no.6
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    • pp.743-751
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    • 2012
  • This paper investigates an experimental behavior of circular columns and beam-columns made of HSB600 high strength steel as a fundamental study to enhance the applicability of HSB steel. The applicability of the current Standard such as KBC and Eurocode 3 is also evaluated. A total of six specimens are fabricated and tested. The main parameters are slenderness ratio(KLe/r = 12, 14, 40, 65), diameter-to-thickness ratio(D/t = 25, 40), and eccentricity ratio(e/D = 0, 0.5). It is drawn from the experiment that both the KBC and Eurocode 3 can be used to predict the strength of circular columns and beam-columns made of HSB600 high strength steel.

Structural Performance of High-Strength Concrete-Filled Steel Tube Steel Columns using Different Strength Steels (이종강종을 사용한 고강도 CFT 합성부재의 구조성능)

  • Choi, In Rak;Chung, Kyung Soo;Kim, Jin Ho;Hong, Geon Ho
    • Journal of Korean Society of Steel Construction
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    • v.24 no.6
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    • pp.711-723
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    • 2012
  • Structural tests were performed to investigate the structural performance of concrete-filled steel tube column using different strength steels in their flange and web with high-strength steel HSA800 and mild steel SM490, respectively. The test parameters included the strength of column flange and infill concrete, and effect of concrete infill. Connection between different grade steels were welded using the electrode appropriate for mild steel and verified its performance. To evaluate the behavior of test specimens, eccentric loading tests were performed and the results were compared with the prediction by current design codes. Axial load and moment carrying capacity of test specimens increased with the yield strength of compression flange and weld fracture occurred after the specimen shows full strength. The prediction result for axial load-bending moment relationship and effective flexural stiffness gave good agreement with the test result.

Force-Deformation Relationship of Bearing-Type Bolted Connections Governed by Bolt Shear Rupture (볼트 전단파단이 지배하는 지압형식 볼트접합부의 힘-변형 관계)

  • Kim, Dae Kyung;Lee, Cheol Ho;Jin, Seung Pyo;Yoon, Seong Hwahn
    • Journal of Korean Society of Steel Construction
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    • v.27 no.1
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    • pp.1-12
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    • 2015
  • Well-designed bolted connections can exhibit excellent ductile behavior through bearing mechanism until the occurrence of bolt shear rupture. The ultimate strength analysis of eccentric bolted connections is an economical and mechanistic approach which uses such ductility. However, the bolt load-deformation relationship, which forms basis of the current practice, is based on very limited combinations of bolt and steel materials. The primary objective of this study was to establish the general bolt force-deformation relationship based on systematic single-bolt bearing connection tests. The test results showed that the projected area of the bolt hole and the strength and thickness of the plate to be connected are the main factors affecting the force-deformation relationship. The results of this study can be used for the instantaneous center of rotation method (ICRM) to achieve more accurate analysis and economical design of a variety of group-bolted connections subjected to eccentric shear.

Development of DCOC Algorithm Considering the Variation of Effective Depth in the Optimum Design of PRC Continuous Beam (PRC연속보 최적설계에서 단면의 유효깊이 변화를 고려한 DCOC알고리즘 개발)

  • 조홍동;한상훈
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.281-291
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    • 2002
  • This paper describes the minimum cost design of prestressed reinforced concrete (PRC) hem with rectangular section. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non prestressing steel, and formwork is minimized. The design constraints include limits on the minimum deflection, flexural and shear strengths, in addition to ductility requirements, and upper-Lower bounds on design variables as stipulated by the specification. The optimization is carried out using the methods based on discretized continuum-type optimality criteria(DCOC). Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables - effective depth, eccentricity of prestressing steel and non prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. In this paper the effective depth is considered to be freely-varying and one uniform for the entire multispan beam respectively. Also the maximum eccentricity of prestressing force is considered in every span. In order to show the applicability and efficiency of the derived algorithm, several numerical examples of PRC continuous beams are solved.

Strength of Interior Plat Plate-Column Connections Subjected to Unbalanced Moment (불균등 휨모멘트를 받는 플랫 플레이트-기둥 접합부의 강도산정모델)

  • 최경규;박홍근
    • Journal of the Korea Concrete Institute
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    • v.14 no.6
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    • pp.961-972
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    • 2002
  • Flat plate structures under lateral load are susceptible to the brittle shear failure of plate-column connection. To prevent such brittle failure, strength and ductility of the connection should be ensured. However, according to previous studies, current design methods do not accurately estimate the strength of plate-column connection. In the present study, parametric study using nonlinear finite element analysis was performed for interior connections. Based on the numerical results, a design method for the connection was developed. At the critical sections around the connection coexist flexural moment and shear developed by lateral and gravity loads, and maximum allowable eccentric shear stresses were proposed based on the interactions between the flexural moment and shear, The proposed method can precisely predict the strength of the connection, compared with the current design provisions. The predictability of the proposed method was verified by the comparisons with existing experiments and nonlinear numerical analyses.

Sensitivity Analysis of Design Parameters for Quadruple Offset Butterfly Valve by Operating Torque (작동 토크를 평가 함수로 하는 사중편심 버터플라이밸브 설계 파라미터 민감도 분석)

  • Lee, Dong-Myung;Kim, Soo-Young
    • Journal of Ocean Engineering and Technology
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    • v.28 no.2
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    • pp.160-166
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    • 2014
  • Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange centerline and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction between the parameters was insignificant.

Fire Damaged Behavior of Real Sized Normal Strength RC Columns (화해를 입은 실물크기 보통강도 RC 기둥의 거동)

  • Lee, Cha-Don;Shin, Yeong-Soo;Hong, Sung-Gul;Lee, Kyung-Ku;Lee, Seung-Whan
    • Journal of the Korea Concrete Institute
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    • v.15 no.6
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    • pp.866-876
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    • 2003
  • Experiments were performed for the real sized 12 reinforced concrete columns of 350×350×3350 mm with normal concrete in order to observe the fire-damaged behavior of these columns. Columns were heated according to the ISO heating curve. Main experimental parameters were: magnitude of axial load, heating time, cover thickness, and eccentricity. Effects of these parameters on the axial expansion and contraction, rotation, buckling, ISO fire resistance, and structural stability were experimentally quantified. It has been observed that the contraction rate of axial deformation was affected mostly by the duration of heating time and buckling of reinforcement or member by the magnitude of axial load, duration of heating time, cover thickness and eccentricity in order. Based on the experimental observations, ISO fire resistance criteria were qualiatively criticized.

Lubrication Effect of Journal Bearing according to its Eccentricity and Attitude Angle (베어링 편심도와 자세각에 따른 저어널 베어링의 윤활효과)

  • Kim, Jong-Do;Wang, Yi-Jun;Yoon, Moon-Chul
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.5
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    • pp.88-95
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    • 2015
  • The thickness of adsorbed molecular layers is the most critical factor in studying thin-film lubrication, and it is the most essential parameter that distinguishes thin-film from thick-film lubrication analysis. The thin film between the shaft and bearing surface within a very narrow gap was considered. The general Reynolds equation has been derived for calculating thin-film lubrication parameters affecting the performance of the circular journal bearing. Investigation of the load-carrying capacity and pressure distribution for the journal bearing considering the adsorbed layer thickness has been carried out. A Reynolds equation appropriate for the journal bearing is used in this paper for the analysis, and it is discussed using the finite difference method of the central difference scheme. The parameters, such as eccentricity and attitude angle, are used for discussing the load-carrying capacity of the journal bearing. The results reported in this paper should be applied to analysis of the journal bearing with different lubrication factors. The steady-state analysis of the journal bearing is conducted using the Reynolds model under thin-film lubrication conditions. For a journal bearing, several parameters, such as a pressure, load capacity, and pressure components of the bearing can be obtained, and these results can be stored in a sequential data file for later analysis. Finally, their distribution can be displayed and analyzed easily by using the MATLAB GUI technique. The load-carrying capability of the journal bearing is observed for the specified operating conditions. This work could be helpful for the understanding and research of the mechanism of thin-film lubrication.

Behavior of N-joints using Square Hollow Sections in Truss (각형강관 트러스의 N형 접합부의 거동)

  • Lee, Sang Ho;Lee, Sang Sup;Bae, Kyou Woong;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.11 no.3 s.40
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    • pp.251-258
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    • 1999
  • The aim of this paper is to examine the behavior of the N-joints using square hollow sections and to improve the structural performance without reinforcing the joints. The selected parameters are the ratio of web to chord width, gap to chord width and eccentricity to chord width. Comparison between test results and codes shows the fact that the NPE-type has superior structural properties to the NSE-type in ultimate strength and deformation capacity. The experimental formulae based on the regression analysis are proposed. Ultimate strength formula employed in eurocode 3 is revised and proposed for the NSE-type. And ultimate strength formula including the eccentricity to chord width ratio which effects on the ultimate strength is proposed for the NPE-type.

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Low-Load/Low-Eccentricity Performance Improvement Designs for Hydro Power Application of Cylindrical Turbine Guide Bearings - Introduction of Pad Leading-Edge Tapers (수력 원통형 터빈 가이드 베어링의 저부하/저편심 성능향상 설계 - 패드 선단 테이퍼의 도입)

  • Lee, An Sung;Jang, Sun-Yong
    • Tribology and Lubricants
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    • v.33 no.2
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    • pp.65-70
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    • 2017
  • In vertical hydro/hydraulic power turbine-generator applications, traditionally, cylindrical turbine guide bearings (TGBs) are widely used to provide turbine runner shafts with smooth rotation guides and supports. All existing cylindrical TGBs with simple plain pads have drawbacks such as having no pressure generation and film stiffness at the no-load condition and in addition, at the low-load/low-eccentricity condition, having very low film stiffness values and lacking design credibility in the stiffness values themselves. In this paper, in order to fundamentally improve the low-load/low-eccentricity performance of conventional cylindrical TGBs and thus enhance their design-application availability and usefulness, we propose to introduce a rotation-directional leading-edge taper to each partitioned pad, i.e., a pad leading-edge taper. We perform a design analysis of lubrication performance on 4Pad×4Row cylindrical TGBs to verify an engineering/technical usefulness of the proposed pad leading-edge taper. Analysis results show that by introducing the leading-edge taper to each pad of the cylindrical TGB one can expect a constant high average direct stiffness with a high degree of design credibility, regardless of load value, even at the low-load/low-eccentricity condition and also control the average direct stiffness value by exploring the taper height as a design parameter. Therefore, we conclude that the proposed pad leading-edge tapers are greatly effective in more accurately predicting and controlling rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems to which cylindrical TGBs are applied.