• Ocean Systems Engineering
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• 제4권2호
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• pp.151-167
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• 2014

It is common that analyses of offshore platforms being carried out with the assumption of rigid tubular joints. However, many researches have concluded that it is necessary that local joint flexibility (LJF) of tubular joints should be taken into account. Meanwhile, advanced analysis of old offshore platforms considering local joint flexibility leads to more accurate results. This paper presents an extensive finite-element (FE) based study on the flexibility of uni-planner multi-brace tubular Y-T and K-joints commonly found in offshore platforms. A wide range of geometric parameters of Y-T and K-joints in offshore practice is covered to generate reliable parametric equations for flexibility matrices. The formulas are obtained by non-linear regression analyses on the database. The proposed equations are verified against existing analytical and experimental formulations. The equations can be used reliably in global analyses of offshore structures to account for the LJF effects on overall behavior of the structure.

• 한국해양공학회지
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• 제8권2호
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• pp.141-150
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• 1994

In designing, the strength of tubular joint has been an important problem for integrity of steel structures in which many tubular members are used. This paper presents the results of FEM analysis on stress concentration and fatigue crack initiation life for two types of tubular joints. One is circular and rectangular T type joints which consist of circular brace and rectangular chord. Another is circular and circular T type joints which consist of circular brace and circular chord. FEM analyses were performed under the axial load and in-plane bending moment. The fatigue crack initiation life can be estimated by using $\varepsilon$-N curve and by applying the Palmgren-Miner linear damage rule. According to the results, the stress concentration factor(SCF) of circular and rectangular joints is higher than that of circular and circular joints. The fatigue crack initiation lives of circular-circular joints and circular-rectangular joints were calculated.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.298-303
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• 2016

수직 및 수평의 원형단면 강관으로 구성된 공간프레임 타워는 강재량을 줄이면서도 풍하중의 영향을 완화시킬 수 있는 장점으로 다양한 목적으로 널리 적용되고 있다. 이러한 공간프레임 타워를 하나의 타워구조로 거동하게 하기 위해서는 수직 강관과 수평 강관의 연결부인 강관조인트의 강도 확보가 중요하다. 본 연구에서는 압축과 휨이 동시에 작용하는 강관 T조인트의 강도평가를 수행하였다. AISC, Eurocode3, ISO 19902의 3가지 강관조인트 설계기준을 검토하고, 주강관과 지강관의 세장비를 주요 매개변수로 한 비선형 유한요소해석을 통하여 축력과 모멘트에 대한 극한강도 상호작용을 설계식으로 제안하였다.

• Steel and Composite Structures
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• 제3권2호
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• pp.123-140
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• 2003

The importance of the research on moment-resistant properties of unstiffened tubular joints and the research background are introduced. The performed experimental research on the bending rigidity and capacity of the joints is reported. The emphasis is put on the discussion of the flexural behavior of the joints including sets of geometrical parameters of the joints and several loading combinations. Procedures and results of loading tests on four full size joints in planar KK and X configuration are described in details at first. Mechanical models are proposed to analyze the joint specimens. Three-dimensional nonlinear FE models are established and verified with the experimental results. By comparing the experimental data with the results of the analysis, it is reported reasonable to carry out the structural analysis under the assumption that the joint is fully rigidly connected, and their bending capacities can assure the strength of the members connected under certain limitation. Furthermore, a parametric formula for inplane bengding rigidity of T and Y type tubular joints is proposed on the basis of FE calculation and regression analysis. Compared with test results, it is shown that the parametric formula developed in this paper has good applicability.

• 한국강구조학회 논문집
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• 제27권1호
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• pp.119-129
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• 2015

강재량을 줄이면서도 풍하중의 영향을 완화시킬 수 있는 장점으로, 수평재로 서로 연결된 다수의 수직 원형강관으로 구성된 멀티기둥 풍력타워 시스템은 기존의 단일 실린더형 타워구조에 대한 대안으로 고려될 수 있다. 멀티기둥 타워를 하나의 타워구조로 거동하게 하기 위해서는 수직 강관과 수평 강관의 연결부인 강관조인트의 강도 확보가 중요하다. 본 연구에서는 멀티기둥에 적용될 수 있는 T 조인트의 강도평가를 수행하였다. AISC, Eurocode3, ISO 19902, CIDECT의 4가지 강관조인트 설계기준을 검토하고, 조인트에서 주강관과 지강관의 세장비에 대한 매개변수해석을 통하여 설계기준에서 제공되는 강도산정식의 타당성을 검토하였다.

• 한국강구조학회 논문집
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• 제13권1호
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• pp.9-18
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• 2001

대스팬 철골구조물의 지붕구조로서 강관트러스가 많이 사용되고 있다. 강관트러스는 타 단면(H, L형강 등)에 비하여 구조역학적인 측면에서 유리하다고 할 수 있다. 그러나 지관의 압축력에 의하여 격점부에는 국부좌굴이 발생하고 이로 인하여 구조체 전체의 내력이 격점부의 지배를 받게 된다. 또한 강관 격점부에서의 내력 및 변형 성상은 거동이 복잡하여 정확한 거동을 예측하기 어려울뿐만 아니라 해석적으로 정밀해를 구하기 어렵다. 이 연구에서는 T형 격점부를 대상으로 지관과 주관의 직경비(d/D) 주관경과 두께비(D/T)에 관한 변수를 설정하여 일련의 실험을 진행하고 기초하여 단순한 링해석법을 이용하여 항복하중에 관한 실용해를 제안하였다. 또한 부가적으로 각국에서 제안된 항복하중에 관한 기존의 연구결과와도 비교, 검토하였다.

• Steel and Composite Structures
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• 제43권1호
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• pp.107-116
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• 2022

This paper presents results of numerical studies completed on unreinforced and doubler plate reinforced Elliptical Hollow Section (EHS) T-joints subjected to axial compressive loading on the brace member. Non-linear finite element (FE) models were developed using the finite element code, ABAQUS. Available test data in literature was used to validate the FE models. Subsequently, a parametric study was carried out to investigate the effects of various geometrical parameters of main members and reinforcement plates on the ultimate capacity of reinforced EHS T-joints. The parametric study found that the reinforcing plate significantly increases the ultimate capacity of EHS T-joints up to twice the capacity of the corresponding unreinforced joint. The thickness and length of the reinforcing plate have a positive effect on the ultimate capacity of Type 1 joints. This study, however, found that the capacity of Type 1 orientation is not dependent on the brace-to-chord diameter ratio. As for type 2 orientations, the thickness and length of the reinforcement have a minimal effect on the ultimate capacity. A new design method is introduced to predict the capacity of the reinforced EHS T-joints Type 1 and 2 based on the multiple linear regression analyses.

• Structural Engineering and Mechanics
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• 제74권1호
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• pp.69-82
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• 2020

A significant defect of space structures is the progressive collapse issue which may restrict their applicability. Force limiting devices (FLDs) have been designed to overcome this deficiency, though they don't operate efficiently in controlling the force displacement characteristics. To overcome this flaw, a new type of FLD is introduced in the present study. The "all steel accordion force limiting device" (AFLD) which consists of three main parts including cylindrical accordion solid core, tubular encasing and joint system is constructed and its behavior has been studied experimentally. To improve AFLD's behavior, Finite element analysis has been carried out by developing models in ABAQUS software. A comprehensive parametric study is done by considering the effective design parameters such as core material, accordion wave length and accordion inner diameter. From the results, it is found that AFLD can obtain a perfect control on the force-displacement characteristics as well as attaining the elastic-perfect plastic behavior. Obtaining higher levels of ultimate load carrying capacity, dissipated energy and ductility ratio can be encountered as the main privileges of this device. Ease of construction and erection are found to be further advantages of AFLD. Based on the obtained results, a procedure for predicting AFLD's behavior is offered.