• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.159-165
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• 2003

A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.25-32
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• 2023

In this study, a double wall system is introduced, which was invented to simplify the complicated manufacturing process of the existing precast concrete (PC) double wall systems and to remove defects such as laitance that may occur during the production of concrete panels. An experimental study was conducted to investigate the tensile resisting capacity of the steel tube which is embedded in the precast concrete panel to keep the spacing between PC panels and to prevent damage of the PC panels during transportation and casting concrete onsite. The experiment was planned to determine the detail of effective steel tube connection considering the steel plate treatment method according to the formation of the opening, the presence of embedded concrete, and the reinforcement welding for additional dowel action as key variables. As a result, the ultimate tensile strength increased by 20-30% compared to the control specimen (ST) except for the steel tube specimen (ST_CP) which has steel plates bent inward at the end part of the steel tube. Since the specimen (ST_CON) filled with concrete inside the control specimen has no additional process and cost for the steel tube connections compared to the control specimen during the production of the developed double wall system, it is determined to be the appropriate detail of steel tube connection.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.9-18
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• 2014

Interface behavior and confining effects of concrete-infilled steel tube (CFT) composite beam were investigate based on the experimental observations and numerical analyses. For this purpose, laboratory four-points bending tests were performed for the two test specimens of 1,000mm long CFT composite beams. The test beams were made of ${\phi}110mm$ and 4.5mm thick steel tube and 10mm thick steel web and bottom flange. Therefore, concrete infilled in steel tube was in compression through the entire cross section due to the web and bottom flange. Two end section conditions, with end section cap and without end section cap, were considered in experiments to monitor the relative slip displacement at ends and induce confining effects at center. In numerical aspects, finite element analysis considering steel-concrete interface behavior was performed and compared to the experimental results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.9-17
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• 2015

Interface behavior of concrete-infilled steel tube (CFT) was investigated based on the experimental observations and numerical analyses. Laboratory tests were performed for twelve CFTs that consisted of two different cases of diameters where each diameter case was composed of three different cases of shear span length. Thereby, diameter and shear span parameters were considered to prove the question of whether there exists interface slip between steel tube and infilled-concrete. Confining effect of steel tube to infilled concrete was also investigated by measuring lateral strain as well as longitudinal strain. Based on the study, it was concluded that confining effect of steel tube to infilled-concrete is not influential under flexural loading and therefore, the sectional analysis is an effective way to estimate the flexural strength of CFT.

• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.383-398
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• 2012

A finite element analysis study was performed to investigate the behavior and strength of a Plate-Circular Hollow Section joint stiffened with Rib-plate, Since The strength of plate-Circular Section joint is reduced by joint of stress and local plastic deformation which is caused by wall moment, rib plates are attached to the upper and lower Plate-Circular Hollow Section joint for redistribution of stress. The behaviors of joints stiffened with Rib-plate according to shape of rib and reinforcing method, etc are different from those of joints which is not stiffened. However, the criterion of hollow structural section was limited on some parts. Therefore, this study intends to investigate the behavior and structural capacity of Plate-Circular Hollow Section joints stiffened with Rib-plate and compare the Finite element analysis with the Design Equation. Finally, this study proposes the reasonable ultimate strength formula through the comparisons with other design guide.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.133-144
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• 1995

This study investigated to the properties of structural behaviors through a series of experiment with the key parameter, such as diameter-to-thickness(D/t) ratio, selenderness ratio of steel t~ube and strength of concrete under loading condition simple confined concrete by steel tube as a fundmental study on adaptability with structural members in high-rise building. The obtained results are sumnarised as follow. (1) The fracture mode of confined concrete was presented digonal tension fracture in the direction of $45^{\circ}$ with compression failure at the end of specimen in stub column, but the fracture mode of long column was assumed an aspect of bending fracture transversely. (2) The deformation capacity and ductility effect was increased by confine steel tube for concrete. (3) 'The emprical formula to predict the ultimate capacity of confined concrete by steel tube and concrete filled steel tube column using restraint of concrete considered D / t ratio, selenderness ratio of steel tube anti strength of' concrete were proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1764-1769
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• 2014

Numerical investigations have been conducted on the junction that connect the multi-tubular section and the single shell section in order to evaluate applicability of hybrid sections in wind turbine towers instead of conventional single shell towers. Major characteristics in structural details include extension of multi-tubular member into shell end section, installation of wing stiffeners, and different layout of floor beams. Elastic and nonlinear incremental analyses were conducted to examine stress concentration patterns and ultimate behaviors, respectively. Based on evaluation of structural performance due to vertical and horizontal forces, it has been confirmed that installation of floor beams and wing stiffeners sensitively affect ultimate strength of global wind tower.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.401-402
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• 2023

The shear connection of the vertical construction joint of a slurry wall by the concrete shear key has excellent structural performance and is economical and eco-friendly. However, technology for forming concrete shear keys in the underground is still underdeveloped. This paper proposes the development of the construction technology required to form a concrete shear key at the vertical construction joint of the slurry wall.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.220-227
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• 2005

최근에 수행된 철골모멘트 접합부의 실험 및 해석결과에 의하면, 기둥으로 각형강관을 가진 접합부가 H형강을 기둥으로 사용하는 접합부에 실험체에 비해서 조기에 스캘럽 단부에서 취성파단이 발생하는 열등한 변형능력을 나타냈다. 이는 각형강관 기둥의 면외변형에 따른 보 웨브의 모멘트 전달효율의 저하, 스캘럽이 가지는 노치효과 및 합성보의 구속효과가 주요원인으로 밝혀졌다. 실험결과는 또한 개선된 수평스티프너로 하부 플랜지를 보강한 실험체는 우수한 변형능력을 가짐을 보였다. 본 연구에서는 이러한 영향을 고려하여, 다양한 수평스티프너로 보강된 접합부에 관한 유한요소해석을 실시하였다. 해석결과를 바탕으로 파일럿 테스트를 실시한 결과, 수평스티프너로 보강된 RBS 접합부 (SR)와 연장된 수평스티프너를 가진 접합부(LH)는 우수한 변형능력을 보였다.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.253-261
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• 1998

The buckling length of exterior beam-columns of the first floor in moment resisting steel frames with weak beams is uncertain when plastic hinges occur at the ends of weak beams due to seismic loads. The objective of this study is to investigate the buckling strength of concrete-filled tubular beam-columns and to suggest the reduced buckling length of them to apply to the beam-column design code. The exterior beam-columns are modelized with horizontal displacement restraint springs. Their strength and reduced buckling length are evaluated by numerical analysis.