• Title, Summary, Keyword: longitudinal stiffener

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A Study on the Buckling Behavior of the Web of Box Girders (상자형 복부판의 좌굴 거동에 관한 연구)

  • Lee, Sang Woo;Kwon, Young Bong
    • Journal of Korean Society of Steel Construction
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    • v.9 no.1
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    • pp.37-49
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    • 1997
  • The buckling behavior of the web of steel girders are largely dependent on the size and the location of stiffeners and the restraining effect of top and bottom flanges. Elastic and inelastic buckling analyses based or the Spline Finite Strip Method were executed to study the stiffening effect of the longitudinal stiffener on the web of box girders and to find how the top and bottom flanges had effects on the web, where geometric boundary conditions were limited by both hinged, both fixed and the flange sections. The basic assumption for the longitudinal end boundary conditions was that the vertical stiffeners had the rigidity enough to force nil deflection line on the web panel so that the junction line between web and vertical stiffener was assumed to be hinged boundary conditions. The provisions on the longitudinal stiffener of the plate and box girders of the Korean Standard Highway Bridge Specifications(1995) and AASHTO Specifications(1994 LRFD) were compared with the results obtained numerically for the various longitudinal stiffener size of box girders. Simple equations and design curves for the longitudinal stiffener of the web were proposed for the practical use.

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Elastic Buckling of Elastically Restrained Orthotropic Plate with a Longitudinal Stiffener under In-plane Linearly Distributed Load (면내 선형분포하중을 받으며 두 변이 탄성구속되고 수평보강된 직교이방성판의 탄성좌굴)

  • 권성미;정재호;채수하;윤순종
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.17-20
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    • 2001
  • This paper presents the results of an elastic buckling analysis of elastically restrained orthotropic plate with a longitudinal stiffener under in-plane linearly distributed load. It is assumed that the loaded edges of web plate are simply supported and other two edges are elastically restrained against rotation. The stiffener is modeled as a beam element and its torsional rigidity is neglected. For the buckling analysis Lagrangian multiplier method is employed. The effects of restraint and longitudinal stiffener are presented in a graphical form.

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Web bend-buckling strength of plate girders with two longitudinal web stiffeners

  • Kim, Byung Jun;Park, Yong Myung;Kim, Kyungsik;Choi, Byung H.
    • Structural Engineering and Mechanics
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    • v.69 no.4
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    • pp.383-397
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    • 2019
  • More than one longitudinal web stiffener may be economical in the design of plate girders that have considerably high width-to-thickness ratio of webs. In this study, the bend-buckling strength of relatively deep webs with two horizontal lines of flat plate-shaped single-sided stiffeners was numerically investigated. Linear eigenvalue buckling analyses were conducted for specially selected hypothetical models of stiffened web panels, in which top and bottom junctions of a web with flanges were assumed to have simply supported boundary conditions. Major parameters in the analyses were the locations of two longitudinal stiffeners, stress ratios in the web, slenderness ratios and aspect ratios of web panels. Based on the application of assumptions on the combined locations of the two longitudinal web stiffeners, simplified equations were proposed for the bend-buckling coefficients and compared to the case of one longitudinal stiffener. It was found that bend-buckling coefficients can be doubled by adopting two longitudinal stiffeners instead of one longitudinal stiffener. For practical design purposes, additional equations were proposed for the required bending rigidity of the longitudinal stiffeners arranged in two horizontal lines on a web.

Numerical Study on Required Stiffness of Longitudinal Stiffener in Plate Girders (플레이트 거더의 수평보강재 필요 강성에 관한 해석적 연구)

  • Lee, Kun Joon;Park, Yong Myung;Kim, Byeong Jun;Park, Chan Hee
    • Journal of Korean Society of Steel Construction
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    • v.28 no.1
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    • pp.43-52
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    • 2016
  • A numerical study on required stiffness of the longitudinal stiffener in the webs stiffened with flat plate at one-side of the web was conducted. The longitudinal stiffeners are commonly placed around 0.2D, i.e., 1/5 the web depth due to fabrication convenience although most plate girders for bridges are unsymmetric section. Considering asymmetry of section, aspect ratio of web and the rigidity ratio of longitudinal stiffener(${\gamma}^*$), eigenvalue analysis were performed to evaluate the buckling strength for the webs with a stiffener located at 0.16D~0.24D. Based on the parametric analysis, the required stiffness of the longitudinal stiffener to satisfy the buckling strength specified in AASHTO LRFD specifications was presented.

Buckling Strength of Orthotropic Rectangular Plate with a Longitudinal Stiffener under In-plane Linearly Distributed Loads (면내 선형분포하중을 받는 수평보강재가 설치된 직교이방성판의 좌굴강도)

  • Jung, Jae Ho;Yoon, Soon Jong;Cho, Sun Kyu
    • Journal of Korean Society of Steel Construction
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    • v.10 no.3
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    • pp.393-406
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    • 1998
  • In this study buckling behavior of orthotropic plate with a longitudinal stiffener under in-plane linearly distributed loads is investigated. All edges of plate are assumed to be simply supported and the stiffener is considered as a beam element. For the equation of buckling analysis Rayleigh-Ritz method is employed. The upper limit of the critical stress at various location of stiffener is determined by using Lagrangian multiplier method. Buckling analysis is performed for the various position of stiffener and for the various width ratios between plate and stiffener. The parametric study shows that, when four edges of plate are simply supported, the most effective position for a longitudinal stiffener is at the location of which the upper limit of the stress is the maximum.

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Structural Design on the Vacuum Chamber of Electron Beam Welding System (전자빔 용접기 진공 작업실의 구조설계)

  • Lee, Young-Sin;Ryu, Chung-Hyun;Seo, Jung;Han, Yu-Hee
    • Laser Solutions
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    • v.1 no.1
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    • pp.11-17
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    • 1998
  • The electron beam welding system has the advantages of the high power density, narrow welding section, and small thermal distortion of a workpiece. Recently, the electron beam welding system is widely used to the airplane engineering, nuclear power plant, and automobile industry. In the present paper, the structural analyses on the vacuum chamber of the electron beam welding system are performed by the F.E.M. analysis. The stiffening characteristics on the geometric shape, stiffener height and stiffener span are investigated. The deflection of the stiffened vacuum chamber under pressure is minimized by longitudinal and transverse stiffeners which are continuous in both direction.

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Development of Automatic Painting Unit for Back-side of Longitudinal Stiffeners in Double Hull Blocks (선체블록 론지 이면부 자동 도장 장비 개발)

  • Kim, Eun-Tae;Lee, Dong-Hoon;Kim, Ho-Kyung
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.123-129
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    • 2009
  • Ship painting procedures can be divided into two categories; Out-shell plate painting of the hull and the interior painting of each double gull blocks. It is really hard to apply standardized and automated operations to the latter because the double hull blocks contains a variety of complicated supportive materials and pipes to strengthen the ship structure. In addition their poor working conditions cause painting workers to avoid working in them, resulting in the waste of paints and additional pollution issues. So this research, successfully focused on overcoming the difficulties in working in the complicated blocks and the tough working conditions introduces the main details of automatic equipment systems and their transfer algorism which show how the equipment paints the inner sides of a longitudinal stiffener and moves to another automatically.

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Strengthening of perforated walls in cable-stayed bridge pylons with double cable planes

  • Cheng, Bin;Wu, Jie;Wang, Jianlei
    • Steel and Composite Structures
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    • v.18 no.4
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    • pp.811-831
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    • 2015
  • This paper focuses on the strengthening methods used for improving the compression behaviors of perforated box-section walls as provided in the anchorage zones of steel pylons. Rectangular plates containing double-row continuous elliptical holes are investigated by employing the boundary condition of simple supporting on four edges in the out-of-plane direction of plate. Two types of strengthening stiffeners, named flat stiffener (FS) and longitudinal stiffener (LS), are considered. Uniaxial compression tests are first conducted for 18 specimens, of which 5 are unstrengthened plates and 13 are strengthened plates. The mechanical behaviors such as stress concentration, out-of-plane deformation, failure pattern, and elasto-plastic ultimate strength are experimentally investigated. Finite element (FE) models are also developed to predict the ultimate strengths of plates with various dimensions. The results of FE analysis are validated by test data. The influences of non-dimensional parameters including plate aspect ratio, hole spacing, hole width, stiffener slenderness ratio, as well as stiffener thickness on the ultimate strengths are illustrated on the basis of numerous parametric studies. Comparison of strengthening efficiency shows that the continuous longitudinal stiffener is the best strengthening method for such perforated plates. The simplified formulas used for estimating the compression strengths of strengthened plates are finally proposed.

A Study on the Stiffener of the Watertight Bulkhead of the Fishing Boat. (강제어선(鋼製漁船)의 수밀격벽(水密隔璧) 방요재(防撓材)에 관(關)한 연구(硏究))

  • Chang-Yull,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.2 no.1
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    • pp.3-8
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    • 1965
  • The objects of this paper are to stimulated discussion of the criteria used for deciding the scantling of watertight bulkhead stiffener of steel fishing boats ranged of length of 20 meters to 80 meters and to suggest a method of calculation based on beam theory. Present knowledge is examined and it appears that failure of a bulkhead stiffener is comparatively rare. Regarding its structure bulkhead does not contribute on longitudinal strength of a ship. The strength of a bulkhead stiffener can be treated locally. Assuming bulkhead stiffeners are free ends and fixed ends theoretical required section modulus are calculated and compared with classification societies' rule. Welding effect of a bulkhead stiffener to bulkhead plate and a bracket to stiffener and deck plate are considered. On various conditions of joints are suggested.

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Numerical investigation of buckling strength of longitudinally stiffened web of plate girders subjected to bending

  • Kim, Hee Soon;Park, Yong Myung;Kim, Byung Jun;Kim, Kyungsik
    • Structural Engineering and Mechanics
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    • v.65 no.2
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    • pp.141-154
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    • 2018
  • In this study, the bend-buckling strength of the web in longitudinally stiffened plate girder was numerically investigated. The buckling strength of the reinforced web was evaluated through an eigenvalue analysis of the hypothetical model, in which the top and bottom junctions of the web to the flanges were assumed as simple support conditions. Major parameters in the analysis include asymmetrical cross-sectional property, aspect ratio of the web, stiffener locations, and bending rigidity of the stiffeners. The numerical results showed that current AASHTO LRFD specifications (2014) provides the buckling strength from considerably safe side to slightly unsafe side depending on the location of the stiffeners. A modified equation for buckling coefficients was proposed to solve the shortcomings. The bending rigidity requirements of longitudinal stiffeners stipulated in AASHTO were also investigated. It is desirable to increase the rigidity of the stiffeners when the aspect ratio is less than 1.0.