• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.565-574
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• 2004

The purpose of this paper was to investigate the block shear and the fracture in the net section, according to AISC Specifications, by analysing the shear lag effect in the block shear rupture of the single angle with three or four bolt connection. Specimen with three or four bolt connections showed that failure generally went from block shear with some net section failures to classic net section failures. From the test results, showed that the connection length, the thickness of angle, and reduction factor, which affect the block shear rupture, were investigated. According to the test results, it is suggested that the calculation of the net section rupture capacity by using the reduction factor of U, that was suggested by Kulak, is needed.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.721-730
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• 1998

In this paper, an experimental study have been many studies on the joints of steel structure, for it has great influences on the safety of structures. Research on block shear rupture of the joint receiving pure tension have been done in foreign countries, but not in Korea. This study focuses on the propriety of block shear design code, according to limited state design criteria of steel structures recently established in Korea, by an experiment on the joint of angle tension members. The methods of this study were to compare other study results on block shear rupture mode and ultimate capacity, and to evaluate the propriety of the criteria design code. The result is that tension yield shear ruptures and shear yield tension ruptures happened at the joint, and the experimental rupture load was 15% higher than the capacity entered in the criteria design code. We conclude that it is necessary to revaluate the block shear design code presented by many studies on the limited state design criteria of steel structures.

• Journal of Korean Society of Steel Construction
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• v.11 no.3 s.40
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• pp.291-299
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• 1999

In this paper, an experimental study have been many studies on the propriety of block shear design code. according to limited state design criteria of steel structures recently established in Korea, by an experiment on the joint of H-Beam Flange tension members. The objects of this study were to compare with the results of other studies on block shear rupture mode and ultimate capacity, and to evaluate the propriety of the design criteria. The result is that the joint happened, two types, tension yield-shear ruptures and shear yield-tension ruptures, and the experimental rupture load was 23% higher than the capacity entered in the criteria design code In this criteria, it was found that ultimate strength of block shear of H-Beam Flange was lowly estimated. Therefore, we emphasize the need of estimates on the block shear rupture by carrying out many studies in this field.

• Earthquakes and Structures
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• v.16 no.6
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• pp.665-677
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• 2019

This study utilizes large-scale shake table test to investigate the seismic performance of an isolated bridge with lead rubber bearings crossing an active fault. Two transverse restraining systems with and without shear keys are tested by applying spatially varying ground motions. It is shown that the near-fault span exhibits larger bearing displacement than the crossing-fault span. Bridge piers away from the fault rupture are more vulnerable than those adjacent to the fault rupture by attracting more seismic demand. It is also verified that the shear keys are effective in restraining the bearing displacement on the near-fault span, particularly under the large permanent ground displacement.

• Steel and Composite Structures
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• v.39 no.1
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• pp.35-50
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• 2021

Eccentrically braced frames (EBFs) are utilized as a lateral resisting system in high seismic zones. Links are the primary source of energy dissipation and they are exposed to high deformation, which may lead to buckling. Web stiffeners were introduced to prevent buckling of shear link. AISC 341 provides the required vertical stiffeners for a shear link. In this study, different stiffener configurations were examined. The main objective is to improve the behavior of short links using different stiffener configurations. Pursuant to this goal, a comprehensive numerical study is conducted using ABAQUS. Shear links with different stiffener configurations were subjected to cyclic loading using loading protocol mandated by AISC 341. The results are compared in terms of energy dissipation and shear capacities and rupture index. The proposed stiffener configurations were further verified with different link length ratios, I-shapes and thickness of stiffener. Based on the results, the stiffener configuration with two vertical and two diagonal stiffeners perpendicular to each other is recommended. The proposed stiffener configuration can increase the shear capacity, energy dissipation capacity and the ratio of energy/weight up to 27%, 38% and 30%, respectively. Detailing of the proposed stiffener configuration is presented.

• Magazine of the Korea Concrete Institute
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• v.10 no.1
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• pp.133-141
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• 1998

FRP는 비부식성 및 고강도의 뛰어난 성질에도 불구하고 콘크리트 구조에 사용하는 데 있어서 소성의 결핍 및 낮은 전단강도와 같은 몇가지의 기술적인 단점을 가지고 있다. 특히 이 두가지 성질은 프리스트레스트 콘크리트보에 있어서 다우얼 작용이 일어나는 전단균열 단면에서와 같이 인장과 전단의 복합효과가 일어날 때 텐던의 조기 파괴를 일으키기 쉽다. 본 논문에서는 탄소 FRP연선을 사용한 프리스트레스트 콘크리트보에서의 텐던파열에 의한 전단파괴를 연구하였다. 전단시험 결과에 의하면 전단 텐던 파괴는 FRP를사용한 프리스트레스트 보에서만 일어나는 유일한 파괴형식으로 보의 전단강도를 저감시키는 것으로 확인되었다. 이러한 전단 텐던 파괴 과정을 규명하기 위하여 다우얼 시험을 실시하고 최초로 실용적인 시험장치 및 과정을 소개하였다. 다우얼 시험 결과에 의하면 FRP 연선은 인장과 전단의 상호작용에 의해 Tsai-Hill 파괴 기준에 따라 파괴되었다.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.983-992
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• 2005

The shear failure modes of fiber reinforced polymer(FRP) strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are strengthened with larger amount of FRP composites, the beams normally fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the actual rupture strain must be known. The equations previously reported in the technical literature adopt an effective reduction factor for the rupture strain. These equations may not be applicable to FRP strengthened RC beams that are beyond the experimental application limits, because most of these equations are empirical in nature. This paper presents the results of an analytical study on the performance of reinforced concrete beams externally wrapped with FRP composites and internally reinforced with conventional steel stirrups.

• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1432-1440
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• 2005

High-temperature rupture behavior of 5083-Al alloy was tested for failure at 548K under multiaxial stress conditions: uniaxial tension using smooth bar specimens, biaxial shearing using double shear bar specimens, and triaxial tension using notched bar specimens. Rupture times were compared for uniaxial, biaxial, and triaxial stress conditions with respect to the maximum principal stress, the von Mises effective stress, and the principal facet stress. The results indicate that the von Mises effective and principal facet stresses give good correlation for the material investigated, and these parameters can predict creep life data under the multiaxial stress states with the rupture data obtained from specimens under the uniaxial stress. The results suggest that the creep rupture of this alloy under the testing condition is controlled by cavitation coupled with highly localized deformation process, such as grain boundary sliding. It is also conceivable that strain softening controls the highly localized deformation modes which result in cavitation damage in controlling rupture time of this alloy.

• Geomechanics and Engineering
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• v.14 no.2
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• pp.195-202
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• 2018

Many laboratory experiments on crack propagation under uniaxial loading and biaxial loading have been conducted in the past using transparent materials such as resin, polymethyl methacrylate (PMMA), etc. However, propagation behaviors of three-dimensional (3D) cracks in rock or rock-like materials under tri-axial loading are often considerably different. In this study, a series of true tri-axial loading tests on the rock-like material with two semi-ellipse pre-existing cracks were performed in laboratory to investigate the acoustic emission (AE) characteristics and propagation characteristics of 3D crack groups influenced by intermediate principal stress. Compared with previous experiments under uniaxial loading and biaxial loading, the tests under true tri-axial loading showed that shear cracks, anti-wing cracks and secondary cracks were the main failure mechanisms, and the initiation and propagation of tensile cracks were limited. Shear cracks propagated in the direction parallel to pre-existing crack plane. With the increase of intermediate principal stress, the critical stress of crack initiation increased gradually, and secondary shear cracks may no longer coalesce in the rock bridge. Crack aperture decreased with the increase of intermediate principal stress, and the failure is dominated by shear fracturing. There are two stages of fracture development: stable propagation stage and unstable failure stage. The AE events occurred in a zone parallel to pre-existing crack plane, and the AE zone increased gradually with the increase of intermediate principal stress, eventually forming obvious shear rupture planes. This shows that shear cracks initiated and propagated in the pre-existing crack direction, forming a shear rupture plane inside the specimens. The paths of fracturing inside the specimens were observed using the Computerized Tomography (CT) scanning and reconstruction.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.371-374
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• 2005

The research reported in this paper provides the test results of eleven reinforced concrete beams strengthened with FRP composites. Three parameters were considered in this investigation: the amount of FRP composites, the types of bonding schemes(continuous sheets or strips), and the material types of FRP composites (Carbon or Glass). The experimental results indicated that because the rupture strain of FRP composites was relatively higher that the yield strain of steel bars, the RC beams strengthened with FRP composites failed due to concrete crushing before the FRP composites arrived at its rupture strain. The compatibility-aided truss model showed reasonable agreement between the predicted and experimental shear stress-strain curves of the beams throughout the entire loading history.