• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.130-138
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• 1994

Bottom plates of empty hold are subjected to not only water pressure but also bi-axial inplane loads, specially in the alternate full loading full loading condition of bulk carrier. This kind of plate behaviours is very difficult to be explained and to be estimated using common buckling design guide in the initial design stage of hull structure, therefore, some more concrete studies for this plate structure was performed based on the currently developed buckling estimation formula. In this buckling formula, torsional stiffness effects of edge stiffener are included additionally and effects of elastic buckling strength of plate panel are treated as characteristic value problem. Also considering boundary stiffener effects and inplane and lateral loading, evaluation of bottom plate scantling using this formula, calculated results using various classification regulation of buckling strength and results of first report approach are compared each other and useful guides using developed formula for bottom plate scantling design are discussed.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.115-130
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• 2013

In this study, lateral-torsional buckling (LTB) strength of high-strength H-beams built up from 800MPa tensile-strength steel was experimentally and analytically evaluated according to current lateral stability provisions (KBC 2009, AISC-LRFD 2010). The motivation was to evaluate whether or not current LTB provisions, which were originally developed for ordinary steel with different stress-strain characteristics, are still applicable to high-strength steel. Two sets of compact-section specimens with relatively low (Set A) or high (Set B) warping stiffness were prepared and tested under uniform moment loading. Laterally unbraced lengths of the test specimens were controlled such that inelastic LTB could be induced. All specimens exhibited LTB strength exceeding the minimum limit required by current provisions by a sufficient margin. Moreover, some specimen in Set A reached a rotation capacity required for plastic design, although its laterally unbraced length belonged to the inelastic LTB range. All the test results indicated that extrapolation of current provisions to high-strength steel is conservative. In order to further analyze the test results, the relationship between inelastic moment and laterally unbraced length was also derived in explicit form for both ordinary- and high-strength steel based on the effective tangent modulus of inelastic section. The analytical relationship derived again showed that extrapolation of current laterally unbraced length limit leads to a conservative design in the case of high-strength steel and that the laterally unbraced length to control the inelastic LTB behavior of high-strength steel beam should be specified by including its unique post-yield strain-hardening characteristics.

• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.123-134
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• 2017

Ultimate axial strength of longitudinally stiffened cylindrical steel shells for wind turbine tower was investigated by applying the geometrically and materially nonlinear finite element method. The effects of radius to thickness ratio of shell, shape and amplitude of initial imperfections, area ratio between effective shell and stiffener, and stiffener spacing on the ultimate axial strength of cylindrical shells were analyzed. The ultimate axial strengths of stiffened cylindrical shells by FEA were compared with design buckling strengths specified in DNV-RP-C202. The shell buckling modes obtained from a linear elastic bifurcation FE analysis as well as the weld depression during fabrication specified in Eurocode 3 were introduced in the nonlinear FE analysis as initial geometric imperfections. The radius to thickness ratio of cylindrical shell models was selected to be in the range of 50 to 200. The longitudinal stiffeners were designed according to DNV-RP-C202 to prevent the lateral torsional buckling and local buckling of stiffeners.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.493-501
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• 2007

Recently, in the domestic amount of materials,curtailment and economic efficiency security by purpose, tapered beam application is achieved, but the architectural design technology of today based on the material non-linear method does not consider solutions to problems such as brittle fracture. So, geometric non-linear evaluation thatincludes initial deformation, width-thickness ratio, web stiffener and unbraced length is required. Therefore, in this study, we used ANSYS, a proven finite elementanalysis program,and material and geometric non-linear analysis to study existing and completed tapered H-section as deep beam's analysis model. Main parameters include the width-thickness ratio of web, stiffener, and flange brace, with the experimental result obtained by main variable buckling and limit strength evaluation. We made certain that a large width-thickness ratio of the web decreases the buckling strength and short unbraced web significantly improves ductility.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.45-52
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• 2005

The object of this study was a cold-formed steel wall stud panel sheathed by gypsum boards. In the beam-analysis, the panel was treated as a simple beam with a uniform lateral loading. The deflections were calculated by considering the primary factors that reduced the stiffness of the panel. In the column-analysis, the panel was treated as a bearing wall with an axial load. By using an energy method, nominal axial strength could be evaluated by considering both flexural buckling and torsional-flexural buckling. All calculations were programmed and compared with the results of the experiment. In the beam-analysis, experimental deflections were close to theoretical deflections. In the column-analysis, the experimental values were also close to theoretical values in axial strength.

• Structural Engineering and Mechanics
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• v.57 no.5
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• pp.785-808
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• 2016

An innovative Reduced Beam Section (RBS) connection, called Tubular Web RBS connection (TW-RBS), has been recently introduced and its performance has been numerically investigated in some earlier studies. The TW-RBS connection is a kind of accordion-web RBS connection in which part of the flat web of the beam is replaced by a steel tube at the expected region of the plastic hinge. This paper presents experimental results of three TW-RBS connections under cyclic loading. Obtained results indicated that TW-RBS reduces contribution of the beam web to the whole moment strength and creates a ductile fuse far from components of the beam-to-column connection. Besides, TW-RBS connection can increase story drift capacity up to 9% in the case of shallow beams which is much more than those stipulated by the current seismic codes. Based on the experimental results, the tubular web in the plastic hinge region improves lateral-torsional buckling stability of the beam such that only local buckling of the beam flange at the center of the reduced section was observed during the tests. In order to achieve a better understanding, behavior of all TW-RBS specimens are also numerically investigated and compared with those of experimental results.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.848-851
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• 2012

본 연구에서는 서해안의 지역적 특성을 고려한 말뚝지지형 조립식 잔교의 상부구조를 구성하는 요소 부재인 주거더 ㄷ형강과 가로보 및 가로거더 H형강에 대해 횡-비틀림 좌굴(Lateral-Torsional Buckling) 여부와 부재별 좌굴강도 값을 유한요소해석을 통해 산정하였으며, 산정한 좌굴강도 값과 부재에 작용하는 설계하중에 대한 안전성 검토를 하였다.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.464-467
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• 2011

본 논문에서는 기존에 수행된 비탄성 영역 내 비지지 길이가 존재하고 균일단면을 가지는 I형 보의 좌굴 강도에 대한 해석적 이론적 연구를 토대로 변단면 I형보의 하중고 효과를 고려한 비탄성 횡-비틀림 좌굴강도에 대한 연구를 수행하였다. 유한요소해석에는 4절점 쉘요소인 S4R요소가 사용되었고, 플랜지 길이방향 비, 너비방향 비, 두께의 비로 스텝보를 나타내었으며, 집중하중을 작용시켰다. 개발된 좌굴강도 제안식은(오정재 등, 2011)과 해석결과를 하중고 효과 평가 시 큰 단면변화를 보이는 경우를 제외하고는 ${\pm}10%$의 오차범위를 나타내었다. 본 연구 결과는 다양한 형식의 I형보가 사용되는 빌딩 및 교량의 경제적이고 합리적인 설계의 근간을 제공해 줄 것이며, 향후 비탄성 횡-비틀림 좌굴강도에 대한 연구에도 많은 도움이 될 것이다.

• Steel and Composite Structures
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• v.10 no.3
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• pp.223-243
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• 2010

This paper reports recent developments concerning the application of Generalised Beam Theory (GBT) to the structural analysis of steel-concrete composite bridges. The potential of GBT-based semi-analytical or finite element-based analyses in this field is illustrated/demonstrated by showing that both accurate and computationally efficient solutions may be achieved for a wide range of structural problems, namely those associated with the bridge (i) linear (first-order) static, (ii) vibration and (iii) lateral-torsional-distortional buckling behaviours. Several illustrative examples are presented, which concern bridges with two distinct cross-sections: (i) twin box girder and (ii) twin I-girder. Allowance is also made for the presence of discrete box diaphragms and both shear lag and shear connection flexibility effects.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.382-385
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• 2007

본 연구에서는 기존 연구를 토대로 하여 비탄성 구간에 있는 계단식 I형보의 횡-비틀림 좌굴강도를 범용구조해석 프로그램 ABAQUS(2006)를 이용하여 산정하고, 간편한 설계식을 제안하고 있다. 본 연구 결과는 다양한 형식의 I형보가 사용되는 빌딩 및 교량의 경제적이고 합리적인 설계의 근간을 제공해 줄 것이며, 향후 다양한 하중 조건을 가지는 양단 또는 일단 계단식 단면 변화보의 비탄성 횡-비틀림 좌굴강도를 계산할 수 있는 설계식 개발에 적극 활용 될 수 있을 것이다.