• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.131-136
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• 2006

일면전단시험은 전단면의 응력을 직접 측정하므로 평면변형시 강도를 파악할 수 있는 등의 많은 장점을 가지고 있으며, 시험조작이 간편하기 때문에 실용적으로도 우수한 것으로 판단된다. 그러나 사질토의 경우에 의한, Dilatancy에 의한 체적변화과정에서 공시체와 전단상자의 주면마찰력이 전단면의 수직 응력을 증감시키기 때문에 구해지는 강도가 과대 또는 과소하게 나타나는 것으로 알려져 있다. 그러나 반력판측에 장착한 하중계를 통해 전단면의 수직응력을 직접 측정 제어하는 형식으로 개선되어 주면마찰력의 영향을 해소하였다. 따라서 본 연구는 반력판측에 하중계를 장착한 개량형 다단식 단순전단시험기를 개발하여 사질토의 정압(CD)조건 전단시험을 수행하여 강도특성과 전단강도에 미치는 영향을 개량형 일면전단시험의 결과와 비교하였다. 그 결과 정압조건의 일면전단시험과 단순전단시험에 의한 강도정수는 조밀한 모래의 경우는 거의 비슷하게 나타나며, 느슨한 모래의 경우는 일면전단이 다소 크게 나타났다. 그리고 단순전단과 일면전단시험에서의 Dilatancy거동에는 큰 차이가 나타나지 않았다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.55-63
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• 2018

Recently, the use of duplex stainless steel which with a two-phase microstructure (equal mixture of ferrite and austenite) has been increased in a variety of industrial fields due to higher strength leading to weight saving, greater corrosion resistance(particularly, stress corrosion cracking) and lower price. However, currently, stainless steels are not included in the structural materials of Korean Building Code and corresponding design standards are not specified. In this paper, experimental studies have been performed to investigate the structural behaviors of duplex stainless steel (STS329FLD) bolted connection with two bolts for providing the design data. Main variables are shear connection type (single shear and double shear) and end distance parallel to the direction of applied force. Fracture modes at the final step of test were classified into typical block shear fracture, tensile fracture and curling. Curling occurrence in single shear connection led to ultimate strength drop by up to 20%. Test strengths were compared with those by current design specifications such as AISC/AISI/KBC, EC3 and AIJ and proposed equations by existing studies. For specimens with no curling, Clement & Teh's equation considering the active shear plane provided a higher strength estimation accurancy and for specimens with curling, Kim & Lim's equation considering strength reduction by curling was also overly unconservative to predict the ultimate strength of curled connections.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.137-144
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• 2005

A direct shear test is classified roughly by one side simple shear test of confining horizontal displacement type and torsional shear test of non-confining one. Direct shear test that has been widely used so far has some problems with test apparatus, testing and the analysis, and in particular that its strength value is everestimated in sandy soils. Also, progressive failure of shearing process happens from shear apparatus restriction and because the shear strain and shear stress are erratic in specimen, we can not define the shear strain value. In the meantime, a simple shear test having advantage of direct shear test is an ideal test method that can get stress-strain relation on shear because it can deliver constant shearing deformation to specimen. However, simple shear test cannot be used practically, because its structure makes tester manufacturing difficult. This paper described a on outline of test apparatus, improvement of test method, and constant pressure test results based on the obtained from improved direct shear apparatus and the standardization of JGS soil testing method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.86-87
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• 2015

An active study on UHPC, which has been recently used in high-rise building and bridges, is in progress. However, research on bonding shear strength of UHPC is required to be studied due to the lack of information. In this study, experimental research progress for bonding shear strength (shear strength of adhesive surface) evaluation of UHPC (Ultra High Performance Concrete) is proceeded. First, specimens that surface treatment methods of concrete bonded section and retardation time of placement are considered are produced. Second, Direct Shear test is applied on concrete bonded section of UHPC. As a result of this study, the highest bonding shear strength specimen in which compared to the non-retardation time specimen is compaction turbulence treatment. From later study, it is judged that strength of UHPC in accordance with direction of steel fiber when steel fiber of UHPC is mixed.

• Geotechnical Engineering
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• v.20 no.11
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• pp.8-16
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• 2004

• Geotechnical Engineering
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• v.20 no.5
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• pp.58-65
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• 2004

일반적으로 토압, 사면안정, 기초의 지지력 계산 등에 이용하는 강도정수를 결정하기 위한 시험법으로는 일축$.$삼축시험과 직접전단시험이 많이 이용되고 있다. 일축$.$삼축시험은 흙 공시체를 축방향으로 압축 또는 신장 파괴시켜서 압축강도를 구하는 것으로, 활동면의 응력을 Mohr-Coulomb의 파괴 기준으로부터 간접적으로 구하기 때문에 간접전단시험으로 불리고 있다. 특히. 삼축시험은 공시체의 주응력 상태가 명확하기 때문에 연구$.$실용면에서 폭넓게 이용되고 있다. (중략)

• Journal of Korean Society of Steel Construction
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• v.25 no.6
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• pp.659-669
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• 2013

The purpose of this study is to investigate the ultimate strength and curling influence using finite element analysis based on the previous test results of ferritic stainless steel bolted connections. Results obtained from finite element analysis (FEA) were compared with those of test results and the validity of numerical modeling was verified. The conditions of curing occurrence for edge/end distance were investigated and ultimate strength reduction ratio caused by curling was estimated quantitatively. Moreover, the ultimate behaviors such as fracture mode and ultimate strength by FEA were compared with those predicted by current design specifications such as AISC, KBC2009, AIJ and AISI.

• Journal of Korean Society of Steel Construction
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• v.30 no.2
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• pp.87-96
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• 2018

This study is aiming at investigating the ultimate behaviors and curling influence on the ultimate strength in high strength aluminum alloys (7075-T6) single shear two-bolted connections using finite element analysis. The validation of finite element analysis for predicting the ultimate behaviors was verified through the comparison between previous test results and analysis predictions. Strength reduction due to curling occurrence was estimated quantitatively. Parametric analyses with extended variables were conducted and the conditions of curling occurrence according to end distance and edge distance were suggested. Finally, modified equation was suggested considering curling influence on the ultimate strength of aluminum alloys 7075-T6 bolted connections.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.463-474
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• 2013

Many experimental and numerical researches for thin-walled carbon steel and austenitic stainless steel single shear bolted connections have been conducted and the modified design equations of ultimate strength were proposed. In this study, the tests of double shear bolted connections with bolt arrangements ($2{\times}1$, $2{\times}2$) and end distance parallel to the loading direction as main variables were performed. Specimens were planed with a constant dimension of edge distance perpendicular to the loading direction, bolt diameter, pitch and gauge like single shear bolted connections. The test results such as ultimate strength and fracture mode were compared with those of current design standards. Furthermore, modified block shear equations for double shear bolted connections were suggested.

• Journal of Korean Society of Steel Construction
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• v.21 no.5
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• pp.527-536
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• 2009

The purpose of this experimental study was to investigate the block shear fracture behavior and curling effect on a single shear-bolted connection in thin-walled carbon steel fabricated with four bolts. The specimens that fail by block shear were planned to have a constant dimension of the edge distance perpendicular to the loading direction, bolt diameter, pitch, and gage. The main variables of the specimens were plate thickness and end distance parallel to the loading direction. A monotonic tensile test was carried out for the bolted connections, and the ultimate behaviors, such as the fracture shape, ultimate strength, and curling, were compared with those that had been predicted using the current design specifications. The conditions of curling occurrence in terms of plate thickness and end distance were also investigated, and the strength reduction due to curling was considered.