• Steel and Composite Structures
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• 제37권1호
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• pp.15-26
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• 2020

The top-and-seat angles with double web angles are commonly used in the design of beam-to-column joints in Asian and North American countries. The seismic behavior analysis of these joints with large cross-section size of beam and column (often connected by four or more bolts) is a challenge due to the effects from the relatively larger size of stiffened angles and the composite action from the adjacent concrete slab. This paper presents an experimental investigation on the seismic performance of exterior composite beam-to-column joints with stiffened angles under cyclic loading. Four full-scale composite joints with different configuration (only one specimen contain top angle in concrete slab) were designed and tested. The joint specimens were designed by considering the effects of top angles, longitudinal reinforcement bars and arrangement of bolts. The behavior of the joints was carefully investigated, in terms of the failure modes, slippage, backbone curves, strength degradation, and energy dissipation abilities. It was found that the slippage between top-and-seat angles and beam flange, web angle and beam web led to a notable pinching effect, in addition, the ability of the energy dissipation was significantly reduced. The effect of anchored beams on the behavior of the joints was limited due to premature failure in concrete, the concrete slab that closes to the column flange and upper flange of beam plays an significant role when the joint subjected to the sagging moment. It is demonstrated that the ductility of the joints was significantly improved by the staggered bolts and welded longitudinal reinforcement bars.

• 한국강구조학회 논문집
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• 제11권2호통권39호
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• pp.167-179
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• 1999

판형복부판의 좌굴강도를 높이기 위하여 수평보강재나 수직보강재를 대는 방법이 많이 적용되고 있다. 경제적인 판형의 설계를 위하여 복부판의 두께를 얇게 하는 대신, 복부판의 전단강도를 높이기 위하여 수직보강재를 사용하게된다. 수직보강재가 있는 복부판의 극한전단강도의 산정에 관한 연구는 1960년 초반부터 활발하게 진행되어 왔고, 이 결과가 미국의 AASHTO 시방서(1973)와 영국의 British Standard(1983)에 처음 반영되어 현재에 이르고 있다. 수평보강재의 주 역할은 휨응력에 의한 복부판의 좌굴강도를 높이고 횡변위를 억제하는 것이지만, 부수적으로 전단강도를 증가시키는 효과가 있는 것으로 알려지고 있다. 하지만, 이에 대한 연구의 부족으로 인하여 수평보강재가 복부판의 극한전단강도에 미치는 영향이 실제 설계시 반영되지 않고 있다. 본 연구에서는 실험을 통하여 수평보강재가 판형의 극한전단거동에 미치는 영향을 조사하고 이를 기존의 이론들과 비교 검토하였다.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3199-3210
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• 1996

The buckling and postbuckling behaviors were sutdied analytically and experimentally for stiffened laminated composite panels under compression loading. The panels with I-, blade, -and hat-shapeed stiffeners were investigated. In the analysis, the stiffened panels were anlyzed using the nonlinear finite element method combined with an improved arc-length method. The progressive failure analysis was done by adopting the maximum stress criterion and complete unloading failure model. The effects of the fiber angles were investigated on the buckling and postbuckling behaviors. In the experiment, the web and the lower cap of each stiffener were formed by the continuous lay-up of the skin for cocuring the stiffened panels. Therefore, the separation between stiffener and skin was not found in the junction part even after postbuckling ultimate load and the stiffened panels had excellent postbuckling load carrying capacity. A shadow moire thchnique was used to monitor the out-of-plane deformations of the panels. The piezoelectric films were attached to the panels to get the failure characteristics of the panel. The analytical results on the buckling load, postbuckling ultimate load, and failure pattern showed good agreement with the experimental results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.344-351
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• 2000

In the design of plate girder web panels, it is required to evaluate accurately the elastic buckling strength under pure shear, pure bending and combined bending and shear. Currently, elastic buckling coefficients of web panels stiffened by transverse intermediate stiffeners are determined by assuming conservatively that web panels are simply supported at the juncture between the flange and web. However, depending upon the geometry and the properties of the plate girder bridge, upper juncture between the flange and web can be assumed as fixed because concrete deck prevents the rotational displacement of upper flange. In the present study, a series of numerical analyses based on finite element modeling is carried out to investigate the effects of the concrete deck, and the resulting data are quantified in simple equations.

• Structural Engineering and Mechanics
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• 제90권2호
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• pp.143-157
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• 2024

Cold-formed steel (CFS) I sections are increasingly being used as load-bearing components in building constructions, and such I sections frequently incorporate web holes to facilitate service installation. The economical and structural advantages of these elements have prompted many researchers to investigate the behavior of such structures. Despite numerous studies on the buckling stability of castellated beams, there is a notable absence of experimental investigation into oval castellated beams with stiffeners. This study examines the local buckling of cold-formed steel castellated I-beams stiffened with oval constellations through experimental and numerical analysis. Four specimens are fabricated with and without stiffeners, including parallel, perpendicular, and intersecting types attached to the web portion of the beam, along with cross stiffeners for the oval-shaped openings at the beam ends. Additionally, a numerical model is developed to predict the behavior of castellated beams with oval openings up to failure, considering both material and geometric nonlinearities. Codal analysis is performed using the North American specification for cold-formed steel AISI S-100 and the Australian/New Zealand design code AS/NZS 4600. The anticipated outcomes from numerical analysis, experimental research, and codal analysis are compared and presented. It will be more helpful to the preliminary designers.

• 한국강구조학회 논문집
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• 제28권1호
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• pp.43-52
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• 2016

본 연구에서는 판 형상의 수평보강재가 한쪽에만 설치되는 통상적인 보강 웨브에서 수평보강재의 필요 강성에 대한 해석적 연구를 수행하였다. 실제 교량용 플레이트 거더는 대부분 비대칭 단면이지만 제작성을 감안하여 수평보강재를 통상 웨브 높이의 1/5인 0.2D 부근에 설치하고 있다. 이러한 점을 감안하여 보강재가 0.16D~0.24D 범위에 설치되는 조건에 대해 단면의 비대칭성과 웨브의 형상비를 고려하여 수평보강재의 강성비(${\gamma}^*$)에 따른 고유치 해석을 수행하고 좌굴강도를 평가하였다. 이로부터 AASHTO LRFD 기준의 좌굴강도를 만족하는 수평보강재의 필요 강성을 제안하였다.

• Steel and Composite Structures
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• 제29권3호
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• pp.309-318
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• 2018

Steel girders are the structural members often used for passing long spans. Mostly being subjected to patch loading, or concentrated loading, steel girders are likely to face sudden deformation or damage e.g., web breathing. Horizontal or vertical stiffeners are employed to overcome this phenomenon. This study aims at assessing the feasibility of a machine learning method, namely the support vector machines (SVM) in predicting the patch loading resistance of longitudinally stiffened webs. A database consisting of 162 test data is utilized to develop SVM models and the model with best performance is selected for further inspection. Existing formulations proposed by other researchers are also investigated for comparison. BS5400 and other existing models (model I, model II and model III) appear to yield underestimated predictions with a large scatter; i.e., mean experimental-to-predicted ratios of 1.517, 1.092, 1.155 and 1.256, respectively; whereas the selected SVM model has high prediction accuracy with significantly less scatter. Robust nature and accurate predictions of SVM confirms its feasibility of potential use in solving complex engineering problems.

• 대한기계학회논문집A
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• 제25권1호
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• pp.106-114
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• 2001

In this study, a shape optimization of stiffener was conducted to increase buckling load or failure load in each case with a different design value and a different objective function for stiffened laminated composite panel of I-type under compression loading. Regarding each of buckling load or failure load as objective function, optimum design was carried out. In respect of optimum design, the effects of relative length of web and cab of stiffener on buckling load or failure load of postbuckling were investigated.

• 한국구조물진단유지관리공학회 논문집
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• 제7권2호
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• pp.169-176
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• 2003

플레이트거더의 전단내력을 평가하기 위해서는 탄성전단좌굴강도가 정확히 산정되어야 한다. 현행 설계식에서는 탄성전단좌굴강도를 계산하기 위한 웨브 플레이트의 경계조건을 4변 단순지지로 가정하고 있다. 그러나 웨브와 플랜지의 경계조건은 일반적으로 단순지지이상의 구속을 가지고 있으며, 플랜지의 두께가 웨브의 두께에 비해 두꺼울수록 고정에 가까워진다. 플레이트거더에서 웨브 플레이트의 경계조건은 플랜지와 웨브의 두께비, 스티프너의 보강간격 등에 따라 달라지게 된다. 본 연구에서는 실험과 유한요소법을 통해 플랜지와 웨브의 폭비, 스티프너의 보강간격, 특히 플랜지와 웨브의 두께비에 따른 웨브 플레이트의 경계조건을 평가하여 플레이트거더의 전단좌굴게수를 제안하고자 한다.

• 한국항해항만학회지
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• 제31권3호
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• pp.235-245
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• 2007

선체의 갑판부와 선저부 그리고 해양구조물의 기본적인 구조는 보강판이다. 보강판넬은 한쪽방향으로 위치한 보강재 혹은 종/횡 방향으로 복잡하게 위치한 구조를 이루고 있으며, 후자의 모델을 그릴리지 구조라고 부른다 선체구조설계 단계에서 선박의 종강도 평가는 가장 중요한 항목이다. 일반적으로, 극심한 해상상태에 놓인 선박의 선저부에는 호깅조건에 의해 발생되는 횡모멘트에 기인하여 압축하중이 작용하게 되며, 이와 동시에 수압하중 작용으로 인한 국부휭모멘트가 작용된다. 본 논문에서는, 구조해석 결과의 검증을 위해서 여러 가지 해석프로그램 및 현재 사용되고 있는 선급룰과의 비교를 하여 횡하중의 영향에 따른 압축최종강도에 대해 분석하고, 여러 가지 설계변수를 변화하여, 각각의 영향을 검토하고, 최종적으로 조합하중 조건에서의 횡하중의 영향에 대해서 분석하였다. 본 연구에서 얻어진 결과들은 최종한계상태설계법에 기반을 두고, 조합하중이 작용하는 선체보강판의 구조강도 거동에 대해서 하중성분에 대한 관계를 고찰하였다.