• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.373-376
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• 2006

The purpose of this study was manufactured and evaluated the bond performance of recycled polyethylene terephthalate(PET) bottle fiber reinforced concrete. Four deformed recycled PET bottle fibers were manufactured and pullout test was conducted in accordance with the JCI-SF 8. Test parameters included four different type of fiber geometry and two types of mortar specimens. According to bond test results, it was found that embossing type recycled PET bottle fiber was significant improving the pullout load and interface toughness.

• Steel and Composite Structures
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• 제6권5호
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• pp.387-400
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• 2006

This paper discusses the composite mechanism and its effect upon the behavior of a steel reinforced concrete (SRC) member subjected to a flexural load. The relationship between member strength and deformation is established using the bond strength between the steel and reinforced concrete. An analytical model is proposed and used to incorporate the sectional strains and bond strength at the elastic and inelastic stages for moment-curvature relationship derivation. The results from the flexural load tests are used to validate the accuracy of the proposed model. Comparisons between the experimental information and the analytical results demonstrate close moment-curvature relevance, which justifies the applicability of the proposed method.

• Advances in concrete construction
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• 제11권5호
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• pp.387-396
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• 2021

The behavior of headed bars in concrete is investigated through 108 pullout tests having an embedment depth of eight times the bar diameter in the M20 concrete mix. Headed bars are designed based on ASTM A970-16 and ACI 318-19 recommendations. The primary parameters used in this study are the steel bar diameter, the steel fibers percentage, and the head shapes. Three failure modes namely, Steel, Concrete-Blowout & Pull-Through failure have been observed. Based on load-deflection curves which are plotted to investigate the bond capacity of headed bars, it is observed that the circular-headed bars have displayed the highest peak load. The comparative analysis shows the smaller differences in the ultimate bond strength between MC2010 (0.89-2.26 MPa) and EN 1992-1-1 (2.32 MPa) as compared to ACI-318-19 (11-22 MPa) which is due to the absence of embedment depth and peak load factor in MC2010 and EN 1992-1-1 respectively.

• 한국강구조학회 논문집
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• 제27권4호
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• pp.359-370
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• 2015

본 연구에서는 AFRP 스트립과 강재사이의 부착거동에 관한 실험적 연구를 수행하였다. 실험적 연구를 통해 AFRP 판과 강판사이의 계면부착거동을 관찰하고, 계면부착응력을 산정하는 것이 본 연구의 목표이다. 실험변수로는 부착길이와 AFRP의 두께를 선택하였으며, 18개의 일면전단시편 제작하여 실험을 수행하였다. 실험결과 부착길이와 AFRP 두께가 증가함에 따라 하중값을 증가하였으며, 부착길이와 AFRP 두께가 증가함에 따라 각각 63%, 86%의 하중값이 증가하였다. 끝으로 강재와 AFRP 사이의 부착응력-슬립관계를 산정하였다. 부착응력-슬립관계는 탄성선형거동을 보이고 있으며, 부착길이와 AFRP 두께는 부착응력과 파괴에너지에 영향을 덜 미치는 것으로 나타났다.

• 대한치과보철학회지
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• 제32권1호
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• pp.47-76
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• 1994

This study was carried out to evaluate the effect of the crack propagation characteristics and bond stress of ceramo-metal system. In order to characterize the crack propagation, the static crack propagation stored in $37^{\circ}C$ distilled water of two commerical porcelains and the dynamic crack propagation under cyclic flexure load of ceramo-metal system were examined. In order to characterize the bond stress, the shear bond test, the 3-point flexure bond test, and the finite element stress analysis of ceramo-metal system were conducted. The results obtained were as follows : 1. Bulk densities and Young's moduli of opaque porcelains increased with repeated firing. 2. Maximum fracture toughness during 4 firing cycles showed at the group of 4 firing cycles in Ceramco porcelain and 2 firing cycles in Vita porcelain. 3. Shear bond strength and flexure bond strength of Ceramco-Verabond specimen were larger than those of Ceramco-Degudent G specimen (p<0.05). 4. Interfacial stresses under three point flexure bond test were concentrated at the edges of ceramometal system. 5. When a cyclic flexure load was applied, the crack growth rate of porcelain surface of ceramometal specimens was decreased as load cycles increased.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.366-369
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• 2006

Deformability of RC members in shear is controlled by governing failure modes and material strength. Shear strength of members in D-regions has been explained by a direct load path (direct strut or arch action) and indirect load path (fan action or truss action). Indirect load path including truss action and fan action rely on bond along tension ties. Generally, superposition of two actions results in total shear strength when shear failure modes control. The ultimate deformation depends on controlling failure modes and thereby, their force transfer patterns. Proposed models are capable of explaining of limited deformability of RC members in D-regions.

• Steel and Composite Structures
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• 제1권4호
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• pp.393-410
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• 2001

In an experimental and analytical study on the structural behavior of slender circular steel-concrete composite columns, eleven specimens were tested to investigate the effects of three ways to apply a load to a column. The load was applied eccentrically to the concrete section, to the steel section or to the entire section. Three-dimensional nonlinear finite element models were established and verified with the experimental results. The analytical models were also used to study how the behavior of the column was influenced by the bond strength between the steel tube and the concrete core and the by confinement of the concrete core offered by the steel tube. The results obtained from the tests and the finite element analyses showed that the behavior of the column was greatly influenced by the method used to apply a load to the column section. When relying on just the natural bond, full composite action was achieved only when the load was applied to the entire section of the column. Furthermore, because of the slenderness effects the columns did not exhibit the beneficial effects of composite behavior in terms of increased concrete strength due to the confinement.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.45-53
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• 1987

The purpose of this study was to evaluate the tensile bond strength between composite resin and the human enamel. Three composite resin systems, two chemical (Clearfil Posterior, and Clearfil Posterior-3) and one light cure (Photo Clearfil-A), used with and without an intermediate resin (clearfil bonding agent), were evaluated under different amounts of load (10g, 200g and 200g for a moment) for in vitro tensile bond strength to acid-eched human enamel. Clinically intact buccal or lingual surfaces of 144 freshly extracted human permanent molars, embedded in acrylic were flattened with No #600 carborundum discs. Samples were randomly assigned to the different materials and treatments using a table of random numbers. Eight samples were thus prepared for each group(Table 2) these surfaces were etched with an acid etchant (Kurarey Co. Japan) in a mode of etching for 30 seconds, washing for 15 seconds, and drying for 30-seconds. During the polymerization of composite resin on the acid-etched enamel surfaces with and without bonding agent 10-gram, 200 gram and temporary 200 gram of load were applied. The specimens were stored in 50% relation humidity at $37^{\circ}C$ for 24 hours before testing. An universal Testing machine (Intesco model No. 2010, Tokyo, Japan) was used to apply tensile loads in the vertical directed (fig 5), and the force required for separation was recorded with a cross head speed of 0.25 mm/min and 20 kg in full scale. The results were as follow: 1. The tensile bond strength was much greater in applying a bonding agent than in not doing that. 2. The tensile bond strength of chemical cure composite resin was higher than that of light cure composite resin with applying on bonding agent on the acid-etched enamel. 3. In case of not applying a bonding agents on the acid-etching enamel, the highest tensile bond strength under 200 gram of load was measured in light cure composite resin. 4. The tensile bond strength under 200-gram of load has no relation with applying the bonding agent. 5. Under the load of 10-gram, There was significant difference in tensile bond strength as applying the bonding agent.

• Journal of Welding and Joining
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• 제33권2호
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• pp.69-77
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• 2015

High strength steels have been continually being developed to improve in fuel economy in automotive and ensure safety of passengers. New bonding and welding methods have been required for improving weldability on high strength steels. In this study, resistance spot welding and Weld-bond with nugget diameters of 4.0mm, 5.0mm, 6.0mm and 7.0mm were produced and tested, respectively. In order to confirm the effect of nugget diameters on tensile shear characteristic of the Weld-bond, tensile shear characteristics of Weld-bond were compared with those of resistance spot welding and adhesive bonding. Peak load of Weld-bond were increased as the nugget diameter increases. After appearing maximum peak load continuous fracture followed with second peak owing to load being carried by resistance spot weldment. Fracture modes of the adhesive layer in Weld-bond fractures were represented by mixed fracture mode, which are cohesive failure on adhesive part and button failure at resistance spot welds. The results showed that the tensile shear properties can be improved by applying Weld-bond on TRIP steel, and more apparent with nugget diameter higher than 5${\surd}$t.

• Computers and Concrete
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• 제9권3호
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• pp.171-178
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• 2012

This paper presents numerical studies of stiff fiber pullout behaviors of fiber reinforced cementitious composites based on a progressive damage model. The ongoing debonding process is simulated. Interfacial stress distribution for different load levels is analyzed. A parametric study, including bond strength and the homogeneity index on the pullout behaviors is carried out. The numerical results indicate that the bond stress decreases gradually from loaded end to embedded end along fiber-cement interface. The debonding initially starts from loaded end and propagates to embedded end as load increasing. The embedded length and bond strength affect the load-loaded end displacement curves significantly. The numerical results have a general agreement with the experimental investigation.