• International Journal of Safety
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• v.11 no.1
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• pp.19-21
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• 2012

In this thesis, fracture test was performed in order to investigate the fracture strength of SFRC(steel fiber reinforced concrete) structures. The relationship between the compressive force and strain value of SFRC specimens were observed under the compressive strength test. From the fracture test results, the relationship between percentage of fiber by volume, compressive strength, elastic modulus, and tensile strength of SFRC beams were studied, and the measured elastic modulus of SFRC were compared with the calculated elastic modulus by ACI committee 544.

• International Journal of Safety
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• v.11 no.2
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• pp.26-28
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• 2012

In this thesis, fracture tests were carried out in order to investigate the flexural strength behavior of FRC(fiber reinforced concrete) structures. FRC beams were used in the tests, the initial crack load and the ultimate load of the beams were observed under the static loading. According to the results, the ultimate loads increase with the fiber content, and these tendency is clear in the specimens with large fiber aspect ratio. From the results of the regression analysis, practical formulae for predicting the flexural strength of FRC were suggested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.176-181
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• 1997

During a compression molding of continuous fiber reinforced composites, the separation of matrix and fiber is caused by the flow of the molding process. As the characteristics of the products are greatly dependent on the separation, it is very important to clarify the separation in relation to molding condition, degree of needle punching number on the degree of nonhomogeneity are studied.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.114-117
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• 2006

Concrete beams reinforced with fiber reinforced polymer (FRP) bars exhibit large deflection and crack width as compared to concrete beams reinforced steel due to modulus of elasticity of FRP bars. Current design code for prediction and crack width developed in concrete structures reinforced with steel bars may not be used for concrete beams reinforced with FRP bars. Thus a number of researcher have attempted to propose modifications to the ACI 318 empirical equation for estimating the effective moment of inertia of reinforced concrete beams. Others used numerical method to calculate the deflection. The purpose of this paper is to evaluation of methods of ACI 440.1 R-01, ISIS Canada design manual, and others for predicting deflection for glass fiber reinforced polymer reinforced concrete beams.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.593-594
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• 2008

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.186-190
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• 2015

$TiO_2$ nanoparticles can be used to improve the performance of carbon fiber-reinforced epoxy resin composites. In this study, the effect of the size of $TiO_2$ nanoparticles on the mechanical properties of carbon fiber-reinforced epoxy resin composites was investigated. The size of the $TiO_2$ nanoparticles was easily controlled using heat treatment. The size of the $TiO_2$ nanoparticles for this study were20nm, 100nm, and 200nm. Three types of carbon fibers with different diameters were also used in this study. The carbon fiber-reinforced epoxy resin composites with 20-nm $TiO_2$ powder showed the highest tensile strength compared to the other types of CFRP, regardless of the fiber maker or fiber diameter. The size of the $TiO_2$ powder and the diameter of the carbon fiber strongly affected the interfacial properties of all kinds of CFRP in this study.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.327-336
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• 2020

Conventional researches on the behavior of fiber-reinforced and unreinforced soils often investigated the failure point. In this study, a concept is proposed in the comparison of the fiber-reinforced with unreinforced sand, by estimating the strength and strength ratio at different levels of strain. A comprehensive program of laboratory drained triaxial compression test was performed on compacted sand specimens, with and without date palm fiber. The fiber inclusion used in triaxial test specimens was form 0.25%-1.0% of the sand dry weight. The effect of the fiber inclusion and confining pressure at 0.5%, 1.0%, 1.5%, 3.0%, 6.0%, 9.0%, 12%, and 15% of the imposed strain levels on the specimen were considered and described. The results showed that, the trend and magnitude of the strength ratio is different for various strain levels. It also implies that, using failure strength from peak point or the strength corresponding to the axial strain of approximately 15% for evaluating the enhancement of strength or strength ratio, due to the reinforcement, may cause hazard and uncertainty in practical design. Therefore, it is necessary to consider the strength of fiber-reinforced specimen at the imposed strain level, compared to the unreinforced specimen.

• Journal of the Korean Wood Science and Technology
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• v.42 no.5
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• pp.571-578
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• 2014

As a way of developing wooden joint development, a glass fiber reinforced wood plate was manufactured to replace a steel plate. Also, the fracture toughness was evaluated. Through application to a cantilever-type specimen made of a column and a beam, the moment resistance performance was evaluated. For the fracture toughness specimen of the wood plate, 12 types were manufactured by varying the combination of a main member (veneer and plywood) and reinforcement (glass fiber sheet and glass fiber cloth). The results of the fracture toughness test indicated that the 5% yield load of the specimen using plywood was 18% higher than that of the specimen using veneer, and that the specimen reinforced by inserting glass fiber sheets between testing materials (Type-3-PS) had the highest average 5% yield load 4841 N. Thus, a moment resistance strength test was performed by applying Type-3-PS to a column-beam joint. The results of the test indicated that compared to the specimen using a steel plate and a drift pin (Type-A), the maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a drift pin (Type-B) was 0.79; and that a rupture occurred in the wood plate due to high stiffness of the drift pin. The maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a glass fiber reinforced wooden laminated pin (Type-C) was 0.67, which showed low performance. However, unlike Type-A, a ductile fracture occurred on Type-C, and the load gradually decreased even after the maximum moment.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.118-121
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• 2006

The research reported here is concerned with the effects of the fiber combination condition and water/cement ratio on the mechanical properties of high performance fiber-reinforced cementitious composites(HPFRCC). An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of HPFRCC were selected using the cylindrical specimens. The results show that W/C ratio is a significant effect factor on the compressive and tensile performance of HPFRCC. The envelope curve concept applies to hybrid fiber-reinforced cementitious composites in tension just as it does to compressive stress-strain curve of fiber-reinforced cement composites. For practical purposes, the tensile envelope curve may be taken to be the same as the monotonic tensile stress-strain curve.

• Journal of Mechanical Science and Technology
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• v.16 no.2
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• pp.192-202
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• 2002

In particle or short-fiber reinforced composites, cracking of the reinforcements is a significant damage mode because the cracked reinforcements lose load carrying capacity. This paper deals with an incremental damage theory of particle or short-fiber reinforced composites. The composite undergoing damage process contains intact and broken reinforcements in a matrix. To describe the load carrying capacity of cracked reinforcement, the average stress of cracked ellipsoidal inhomogeneity in an infinite body as proposed in the previous paper is introduced. An incremental constitutive relation on particle or short-fiber reinforced composites including progressive cracking of the reinforcements is developed based on Eshelby's (1957) equivalent inclusion method and Mori and Tanaka\`s (1973) mean field concept. Influence of the cracking damage on the stress-strain response of composites is demonstrated.