• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.955-962
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• 2008

This study concerns the effect of drainage in reinforced soil on its stability during rainfall. A series of finite-element analysis based transient seepage analysis were performed on a number of cases with different drainage conditions in terms of layers of geotextiles installed in the reinforced zone. The results were then coupled with the limit-equilibrium slope stability analysis to investigate the variation of global stability factor of safety with rainfall infiltration into the reinforced wall. The results were thoroughly analyzed to get insight into the mechanism of pore water pressure reduction effect of the geotextile and into its effect on overall slope stability. It is shown that layers of geotextile installed in the reinforced zone can prevent decrease in suction in the reinforced zone during rainfall, thereby reducing potential risk of decreasing shear strength of the reinforced zone. Practical implications of the findings were discussed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 가을 학술발표회 논문집
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• pp.171-177
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• 1995

Fracture mechanics does work for concrete, provided that one uses a proper, nonlinear form of fracture mechanics in which a finite nonlinear zone at fracture front is being considered. The fracture process zone is a region ahead of a traction-free crack, and the development of model of fracture process zone is most important to describe fracture phenomena in concrete. This paper is about fracture behavior of concrete cylinder under lateral pressure. Concrete cylinders were made of high strength normal connote, steel fiber reinforced concrete and steel fiber reinforced polymer-impregnated concrete and concrete and the fracture behavior such as cracking propagation and ultimate load are observed. The fracture process zone is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve and are implemented to the boundary element technique for the fracture analyses of the cylinders. The experimental results are compared with analysis results and tension-softening curves for the steel fiber reinforced concrete and steel fiber reinforced polymer-impregnated concrete are obtained by back analyses.

• Computers and Concrete
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• 제5권6호
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• pp.525-544
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• 2008

In this research, the self-centering effect in precast and prestressed reinforced concrete structures was investigated experimentally. The reinforced concrete beams and columns were precast and connected by post-tensioning tendons passing through the center of the beams as well as the panel zone of the connections. Three beam-to-interior-column connections were constructed to investigate parameters such as beam to column interfaces (steel on steel or plastic on plastic), energy dissipating devices (unbonded buckling restrained steel bars or steel angles) and the spacing of hoops in the panel zone. In addition to the self-centering effect, the shear strength in the panel zone of interior column connections was experimentally and theoretically evaluated, since the panel zone designed by current code provisions may not be conservative enough to resist the panel shear increased by the post-tensioning force.

• 콘크리트학회논문집
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• 제17권6호
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• pp.911-922
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• 2005

섬유보강 콘크리트 보의 전단강도와 거동 특성을 규명하기 위해서 이론적 연구를 수행하였다. 섬유보강 콘크리트 보의 단면에 작용하는 전단력은 압축대와 인장대에 의해서 지지된다. 압축대의 전단성능은 단면의 휨모멘트에 의해서 발생하는 수직응력과의 상관관계를 고려하여 정의하였으며, 인장대의 전단성능은 섬유보강 콘크리트의 균열 후 인장강도를 고려하여 정의하였다. 보의 휨변형에 따라서 수직응력의 크기와 분포가 변화하므로, 보의 전단성능은 휭변형의 함수로 정의하였다. 전단성능곡선과 전단요구곡선의 교점에서, 보의 전단강도와 위험단면의 위치가 결정된다. 제안된 설계 방법은 섬유보강 콘크리트와 일반 콘크리트 보를 위한 통합전단강도모델로 사용 할 수 있다.

• 한국공간구조학회논문집
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• 제21권1호
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• pp.71-78
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• 2021

The U-flanged truss hybrid beam is a new composite beam made by pouring concrete into the U-flanged truss beam. In this study, an experimental study was performed to verify the shear capacity of U-flanged truss hybrid beams with the newly developed end reinforcement details. For all specimens, the maximum shear strength was determined by shear failure of concrete in the loading point The detail reinforced with stirrups at the end zone can exhibit the greatest shear strength, but the method of reinforcing the end zone using vertical steel plates, which is a relatively easy method to manufacture, is considered to be the most effective detail in terms of shear strength and ductility. Also, in the case of U-flanged truss hybrid beams reinforced with vertical steel plates at the end zone, the shear strength can be evaluated on the safety side by using the Korea Design Standard formula.

• Smart Structures and Systems
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• 제23권2호
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• pp.173-184
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• 2019

The main objective of this study is to evaluate the true fracture energy and monitor the damage progression in steel fibre reinforced concrete (SFRC) specimens using acoustic emission (AE) features. Four point bending test is carried out using pre-notched plain and fibre reinforced (0.5% and 1% volume fraction) - concrete under monotonic loading. AE sensors are affixed at different locations of the specimens and AE parameters such as rise time, AE energy, hits, counts, amplitude and duration etc. are obtained. Using the captured and processed AE event data, fracture process zone is identified and the true fracture energy is evaluated. The AE data is also employed for tracing the damage progression in plain and fibre reinforced concrete, using both parametric- and signal- based techniques. Hilbert - Huang transform (HHT) is used in signal based processing for evaluating instantaneous frequency of the acoustic events. It is found that the appropriately processed and carefully analyzed acoustic data is capable of providing vital information on progression of damage on different types of concrete.

• Computers and Concrete
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• 제4권4호
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• pp.317-330
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• 2007

Steel reinforced concrete is perhaps the most versatile and widely used construction material. The versatility is attributed to mouldability of concrete to any conceivable shape. The inherent property of cracking of concrete is the reason for its low tensile strength and hence the design approach of RCC sections in flexure adopts the cracked section theory where in concrete in tension zone is ignored. Means, modes and methods of exploitation of concrete strength by conceiving shapes other than rectangular whereby ineffective concrete in tension zone is reduced and incorporated in compression zone where it is effective needs consideration. Shape optimization of beams is attempted in this analytical investigation employing Sequential Unconstrained Minimization Technique (SUMT). The results clearly show that trapezoidal beams happen to be less costlier than their rectangular counterparts, their usage needs serious reconsideration by the designers.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.121-128
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• 2001

This is a case study of stability analysis and reinforcement design for the tunnel where the collapse of the entrance slops occured along the fault zone developed in the bed rock. According to the site investigation, the main factor of sliding is the influence of fault gouge and heavy rainfall. Considering the in-situ condition, the versatile reinforcement methods is needed, and so the close investigation on the site area was accompanied with the stability analysis of tunnel and slops. The FRP(Fiberglass reinforced plastic) grouting method improved the defect of Steel Umbrella Arch Method, such as oxidation, low work efficiency, the material's heavy weight, is adapted as the reinforcement methods.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.701-706
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• 2001

This study is aimed to investigate on the structural properties(like as strength, failure mode, ductility) of beams with multiple openings reinforced with steel tube of circular. The main parameters are follows ;1)location of openings, 2)the number of opening, 3) existence of opening or not. When the locations of opening are respectively maximal moment zone, maximal shear zone, co-existence zone of moment and shear, the specimen with opening at maximal moment zone is not less than that without opening in terms of strength and ductility. The specimens with opening at shear zone and both zones are expected to carry the structural performance corresponding to beam without opening by varying the number and reinforcing method of opening.

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.867-883
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• 2016

In this paper, the effects of steel-fiber and rebar reinforcements on the ultimate bearing strength of the local anchorage zone were investigated based on experiments and comparisons between test results and design-equation predictions (AASHTO 2012, NCHRP 1994). Eighteen specimens were fabricated using the same anchorage device, which is one of the conventional anchorage devices, and two transverse ribs were used to secure an additional bearing area for a compact anchorage-zone design. Eight of the specimens were reinforced with only steel fiber and are of two concrete strengths, while six were reinforced with only rebars for two concrete strengths. The other four specimens were reinforced with both rebars and steel fiber for one concrete strength. The test and the comparisons between the design-equation predictions and the test results showed that the ultimate bearing strength and the section efficiency are highly affected by the reinforcement details and the concrete strength; moreover, the NCHRP equation can be conservatively applied to various local anchorage zones for the prediction of the ultimate bearing strength, whereby conditions such as the consideration of the rib area and the calibration factor are changed.