• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.57-64
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• 2001

암석-콘크리트 불연속면의 전단변형 및 파괴특성을 규명하기 위해 상부 재료를 콘크리트로, 하부 재료를 암석으로 하는 규칙.불규칙 톱니형 시료와 인공 절리시료를 제작하여 실험실 직접전단시험을 실시하였다. 전단과정 동안 하중과 변위 외에 미소파괴음의 계수와 에너지를 측정하여 전단과정의 단계별 특징을 규명하였고 미소파괴음 음원추적을 실시하여 불연속면에서의 거칠기 파괴부분의 변화를 고찰하였다. 또한 암석 불연속면과 암석-콘크리트 불연속면의 거동을 비교하고 거칠기의 불규칙성 증가에 따른 전단거동의 변화를 관찰하였다.

• Proceedings of the KSEG Conference
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• 2004.03a
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• pp.24001-24056
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• 2004

암반 기초에서 발생 가능한 파괴형태로는 $\circled1$전단파괴(Shear failure) $\circled2$관입파괴(punch failure) $\circled3$붕락(Collapse) $\circled4$균열파괴 (cracking) $\circled5$분쇄상파괴 (crushing) $\circled6$쐐기상파괴 (wedging)를 들 수 있다. 그림 2.4-1에서 (a)는 연암층 내에서의 전형적인 전단파괴를 나타내고, (b)는 소성암반 상부에 강성암반이 놓였을 때의 전단파괴를 보여준다. (c)는 2층으로 구성된 지반에서의 전단파괴 양상이며, (d)는 편심하중이 작용할 때의 전단파괴이다. (e)는 사면 상에서의 활동에 의한 파괴유형이다. (f)는 절리가 발달한 풍화된 암반내로 진행되는 관입파괴를 보여주고 있다. (e)는 연암지반 내부로 강성암반이 관입되어 파괴된 모습이다. (h)는 풍화된 화강암에서의 관입파괴 유형이다. (i)는 석회암층 내부의 지하공동에 의한 붕락현상을 보여주고 있으며, (j)는 지하수의 유동에 의해 형성된 공동으로 인한 붕락파괴를 나타낸다. (k)는 균열파괴, (l)은 분쇄상 파괴, (m) 쐐기상 파괴, (n)은 단층선을 따른 파괴 유형이다. (중략)

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.1-8
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• 2008

RC beam of existing structures often encounter shear problems for various reasons. The shear failure of RC beam is sudden and brittle. Strengthening technique jacketing with external bonding of steel plates(or CFRP and CFS) with epoxy is many use to in practice. This study presents test results on strengthening shear deficient RC beams by external bonding of slit type steel plates. Test parameters are width, interval, length, thickness and angle of slit in steel plates. The purpose was to evaluate the reinforcing effects, failure modes and shear capacities for RC beams of strengthened with various slit type steel plates. The test result confirmed that all slit steel plates improved the stiffness and strength of the specimens significantly. Failure modes of SV series and SD series showed shear fractures and flexure fractures at ultimate state respectively. SD series were ductile rather than SV series.

• Tunnel and Underground Space
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• v.13 no.1
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• pp.64-75
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• 2003

This study presents a newly suggested test method of Mode II fracture toughness measurement called "Punch Through Shear Test" which was originally proposed by Backers and Stephansson in 2001. The purpose of this study is to check the validity of the suggested testing method by performing Mode II fracture toughness tests for Daejeon Granite. In addition, the optimal specimen geometry for the testing and the relation between Mode II fracture toughness and confining pressure were also investigated. Fractured surface was observed to be very smooth with lots of rock debris which came off fracture surface which obviously implies that the surface was sheared off. This confirms that Mode II fracturing actually occurred. In addition, numerical analyses including continuum analysis, particle flow code analysis and crack propagation simulations were performed. Results of these numerical analyses indicated that the cracks occurred in the specimen were predominantly in Mode II and these cracks led to failure of the test specimen. From this investigation, it can be concluded that the newly suggested "Punch Through Shear Test" method provides a reliable means of determining the Mode II fracture toughness. fracture toughness.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.73-76
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• 2008

According to the survey of earthquake disaster, low-rise reinforced concrete building larger by the extent of damage and because of the underlying distribution of reinforced concrete structures more, it is very likely to be disasters. The purpose of this study is to discuss how strength and stiffness of each system in low-rise reinforced concrete buildings consisted of extremely brittle, shear and flexural failure lateral-load resisting systems have influence on seismic capacities of the overall system. Generally, if shear failure members including extremely brittle failure members are failed during an earthquake, the lateral-load resisting seismic capacities of RC buildings are lower rapidly, and if the seismic capacities of shear failure members were higher than that of flexural failure members, failures of shear failure members have influence on failures of the overall system. The result of this paper will provide pseudo-dynamic test of carried out to estimate the possibility of proposals.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.400-412
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• 2013

For the composite behavior of steel tube and inner concrete, the shear connectors should be applied to the CFT structures. However, the present design codes don't provide the design criteria that can be applied on shear connectors in the CFT structures typically filled with plain concrete. This study has been carried out to propose design criteria (shear strength and resistance factor) for the stud shear connectors in CFT structures. Experimental tests using the push-out specimens with the plain concrete blocks and finite element analysis were conducted for the purpose of verifying the main failure mode to propose the shear strength of studs in CFT structures. From the results of this study, the main failure mode of studs in CFT structures is splitting crack of concrete and this failure mode reduces shear strength of studs in CFT structures relatively to those embedded in RC blocks.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.193-196
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• 2008

This paper presents an experimental study to investigate enhanced performance of the masonry walls strengthened in shear and ductility using honeycomb steel mesh. The performance of masonry walls strengthened with steel mesh will compare with unreinforced masonry walls to show the performance of reinforced masonry walls. According to the experiment, it is expected that this system is effective to enhance the shear strength and ductility of the masonry walls.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.653-659
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• 2002

Recently, the failure case of the bridge deck slabs have been increasing in Korea and it was observed that the failure modes of most deck slabs collapsed were not caused by flexural moment but by local punching shear. The main reason of the failures was the punching shear failure of deck slabs under heavy truck traffics. This paper presents test results obtained from punching shear tests performed on prestressed precast deck specimens. Cracking patterns, failure modes, deflections, and stresses are included as well as discussion of the punching shear strength observed during punching shear tests. Static lest specimens had punching shear failures at loads much higher than predicted by the current codes. Tests results indicate that current code provisions appear to be conservative.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.149-158
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• 2004

In this study, deep beam specimens are designed to have the effective shear span to depth ratio 1.0 and web opening within effective shear region. The purpose of this study is to investigate experimentally the shear strengthening effect between before failure and after failure upon using fiber sheets for RC deep beam with opening in web. The results can be summarized as follows; 1)When deep beams with web opening were failed in shear, their initial diagonal crack load and crack width were not influenced by their types of the arranged steel bars. 2)Deep beam with the horizontal reinforced bar was effective in the ultimate load of deep beam with web opening in shear failure 3)There were the approximate values between the experimental values and the analysis of finite element method. 4)The ultimate failure strengths of the repaired and strengthened specimens were increased about 34.4%~83.8% in comparison with specimens not to be strengthened.