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Joong Kyu Jeon - One of the best experts on this subject based on the ideXlab platform.
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Polyamide Fiber Reinforced Shotcrete for Tunnel Application
Materials, 2016Co-Authors: Joong Kyu Jeon, Wooseok Kim, Gyu-yong Kim, Chan Ki JeonAbstract:This study intends to establish the mechanical properties of Polyamide Fiber reinforced shotcrete (PAFRS) in terms of compressive and flexural strengths, in accordance with ASTM C1609/C1609M-12. The mechanical properties identified the influence of Polyamide Fiber content on the PAFRS strength. This study evaluated the toughness of PAFRS and proposed additional toughness level criteria to better represent organic Fiber performance. In addition, the Fiber rebounding rate and PAFRS performance in tunneling application were evaluated based on a tunnel application in Korea. PAFRS with 0.6%~0.8% volume content in tunneling shotcrete could significantly improve flexural ductility, toughness, and ultimate load capacity. Fiber rebounding tests exhibited a low rebounding rate (8.5%) and low Fiber drop (63.5%). Therefore, PAFRS applied to a tunnel exhibited stability and constructability.
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Assessment of flexural toughness and impact resistance of bundle-type Polyamide Fiber-reinforced concrete
Composites Part B: Engineering, 2015Co-Authors: Hongseop Kim, Gyu-yong Kim, Jeong-soo Nam, Nenad Gucunski, Joong Kyu JeonAbstract:Abstract This study compares the Fiber/matrix bonding strength and flexural properties of bundle-type Polyamide Fibers to those of hooked-end steel Fibers. Their fracture behavior upon impact with a high-velocity projectile is also assessed in terms of penetration depth, crater diameter and rear-side scabbing. The results obtained demonstrate that the bundle-type Polyamide Fibers undergo fracture without Fiber pullout because of the increased interFiber gap and specific surface area for bonding, but exhibit poorer flexural fracture behavior with a lower flexural strength and fracture energy when compared to hooked-end steel Fibers. Yet despite this, concrete reinforced with bundle-type Fibers is shown to more effectively suppress scabbing during high-velocity impact, which is attributed to a more efficacious dispersion of shock stress due to the increased number of individual Fibers.
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Evaluation of Shear Resisting Capacity of a Conventional Reinforced Concrete Wall with Steel or Polyamide Fiber Reinforcement
Journal of korean society of hazard mitigation, 2013Co-Authors: Young-sun Choun, Jang Hwa Lee, Joong Kyu JeonAbstract:A concrete shear wall system is an ideal structural system that can effectively resist large horizontal cyclic loads such as earthquakes. In particular, a significant increase of the ductility in Fiber reinforced concrete shear walls can prevent a brittle failure and thus can enhance seismic resisting capacity significantly. This study investigated the shear resisting capacity of shear wall specimens, which are constructed with steel Fibers or Polyamide Fibers reinforced concrete, by comparing hysteresis curves obtained from reversal cyclic tests. The shear resisting force in the steel Fiber reinforced concrete specimen was larger than those in plain and Polyamide Fiber reinforced concrete specimens, but the increase was not great. The shear resisting capacity of the Polyamide Fiber reinforced concrete specimen was larger than that of plain concrete specimen, but smaller than that of steel Fiber reinforced concrete specimen.
Young-sun Choun - One of the best experts on this subject based on the ideXlab platform.
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evaluation of seismic shear capacity of prestressed concrete containment vessels with Fiber reinforcement
Nuclear Engineering and Technology, 2015Co-Authors: Young-sun Choun, Junhee ParkAbstract:Abstract Background Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of Fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. Methods The effects of steel and Polyamide Fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel Fiber reinforced concrete, and Polyamide Fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. Results The shear resisting capacity of a PCCV constructed with Fiber reinforced concrete can be improved considerably. When steel Fiber reinforced concrete contains hooked steel Fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When Polyamide Fiber reinforced concrete contains Polyamide Fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ∼40%. In particular, the energy dissipation capacity in a Fiber reinforced PCCV can be enhanced by > 200%. Conclusion The addition of Fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel Fibers are more effective in enhancing the shear performance of a PCCV than Polyamide Fibers.
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Containment performance evaluation of prestressed concrete containment vessels with Fiber reinforcement
Elsevier, 2015Co-Authors: Young-sun Choun, Hyung-kui ParkAbstract:Background: Fibers in concrete resist the growth of cracks and enhance the postcracking behavior of structures. The addition of Fibers into a conventional reinforced concrete can improve the structural and functional performance of safety-related concrete structures in nuclear power plants. Methods: The influence of Fibers on the ultimate internal pressure capacity of a prestressed concrete containment vessel (PCCV) was investigated through a comparison of the ultimate pressure capacities between conventional and Fiber-reinforced PCCVs. Steel and Polyamide Fibers were used. The tension behaviors of conventional concrete and Fiber-reinforced concrete specimens were investigated through uniaxial tension tests and their tension-stiffening models were obtained. Results: For a PCCV reinforced with 1% volume hooked-end steel Fiber, the ultimate pressure capacity increased by approximately 12% in comparison with that for a conventional PCCV. For a PCCV reinforced with 1.5% volume Polyamide Fiber, an increase of approximately 3% was estimated for the ultimate pressure capacity. Conclusion: The ultimate pressure capacity can be greatly improved by introducing steel and Polyamide Fibers in a conventional reinforced concrete. Steel Fibers are more effective at enhancing the containment performance of a PCCV than Polyamide Fibers. The Fiber reinforcement was shown to be more effective at a high pressure loading and a low prestress level
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Evaluation of Shear Resisting Capacity of a Conventional Reinforced Concrete Wall with Steel or Polyamide Fiber Reinforcement
Journal of korean society of hazard mitigation, 2013Co-Authors: Young-sun Choun, Jang Hwa Lee, Joong Kyu JeonAbstract:A concrete shear wall system is an ideal structural system that can effectively resist large horizontal cyclic loads such as earthquakes. In particular, a significant increase of the ductility in Fiber reinforced concrete shear walls can prevent a brittle failure and thus can enhance seismic resisting capacity significantly. This study investigated the shear resisting capacity of shear wall specimens, which are constructed with steel Fibers or Polyamide Fibers reinforced concrete, by comparing hysteresis curves obtained from reversal cyclic tests. The shear resisting force in the steel Fiber reinforced concrete specimen was larger than those in plain and Polyamide Fiber reinforced concrete specimens, but the increase was not great. The shear resisting capacity of the Polyamide Fiber reinforced concrete specimen was larger than that of plain concrete specimen, but smaller than that of steel Fiber reinforced concrete specimen.
Yan Er Jhuang - One of the best experts on this subject based on the ideXlab platform.
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the effect of tensile hysteresis and contact resistance on the performance of strain resistant elastic conductive webbing
Sensors, 2011Co-Authors: Tien-wei Shyr, Jing Wen Shie, Yan Er JhuangAbstract:To use e-textiles as a strain-resistance sensor they need to be both elastic and conductive. Three kinds of elastic-conductive webbings, including flat, tubular, and belt webbings, made of Lycra Fiber and carbon coated Polyamide Fiber, were used in this study. The strain-resistance properties of the webbings were evaluated in stretch-recovery tests and measured within 30% strain. It was found that tensile hysteresis and contact resistance significantly influence the tensile elasticity and the resistance sensitivity of the webbings. The results showed that the webbing structure definitely contributes to the tensile hysteresis and contact resistance. The smaller the friction is among the yarns in the belt webbing, the smaller the tensile hysteresis loss. However the close proximity of the conductive yarns in flat and tubular webbings results in a lower contact resistance.
Gyu-yong Kim - One of the best experts on this subject based on the ideXlab platform.
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Strain rate effects on the compressive and tensile behavior of bundle-type Polyamide Fiber-reinforced cementitious composites
Composites Part B: Engineering, 2019Co-Authors: Hongseop Kim, Gyu-yong Kim, Sangkyu Lee, Minjae Son, Gyeongcheol Choe, Jeong-soo NamAbstract:Abstract The compressive and tensile behavior of Fiber-reinforced cementitious composites is significantly affected by the bonding and pull-out properties between matrix and reinforced Fiber, as well as the fracture properties of the Fibers. In addition, an increase in strain rate according to loading conditions influences the fracture behavior between the Fiber and matrix. Steel Fiber-reinforced cementitious composites with high flexural and tensile strength, toughness, and crack resistance are widely used in tunnels and plant structures. However, the high specific gravity and stiffness of steel Fibers can cause rupture of concrete pump tubes, increase the rebound volume of shotcrete, and decrease durability by corrosion of Fiber. Therefore, it is necessary to study the development and application of organic Fiber which has similar mechanical properties to steel Fiber and does not cause corrosion. In this study, Polyamide Fibers having the same aspect ratio as the hooked steel Fibers, which are widely used as reinforcing Fibers for concrete, have been developed. And strain rate effect on the compressive and tensile behaviors of bundle-type Polyamide Fiber-reinforced cementitious composite and hooked steel Fiber-reinforced cementitious composite were evaluated. The results showed that the effect of strain rate over different Fiber types influenced the tensile behavior more significantly than the compressive behavior. In Polyamide Fiber-reinforced cementitious composite (PAFRCC), a fracture behavior of Fiber was observed regardless of a strain rate, and the tensile behavior of PAFRCC was influenced more by tensile strength of Polyamide Fiber itself than a bonding stress between Fiber and matrix. In hooked steel Fiber-reinforced cementitious composite (HSFRCC), a bonding stress between hooked steel Fiber and matrix (frictional force at the interface between Fiber and matrix, mechanical bond of the hooked part) influenced the tensile behavior significantly. Fracture properties that straightened pulled out the Fiber from the matrix were observed at static tensile loading condition. However, non-straightened hooked steel Fiber was observed along with the fracture of matrix due to an increase in mechanical bonding force of the hooked part and the bonding stress between the Fiber and the matrix.
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Polyamide Fiber Reinforced Shotcrete for Tunnel Application
Materials, 2016Co-Authors: Joong Kyu Jeon, Wooseok Kim, Gyu-yong Kim, Chan Ki JeonAbstract:This study intends to establish the mechanical properties of Polyamide Fiber reinforced shotcrete (PAFRS) in terms of compressive and flexural strengths, in accordance with ASTM C1609/C1609M-12. The mechanical properties identified the influence of Polyamide Fiber content on the PAFRS strength. This study evaluated the toughness of PAFRS and proposed additional toughness level criteria to better represent organic Fiber performance. In addition, the Fiber rebounding rate and PAFRS performance in tunneling application were evaluated based on a tunnel application in Korea. PAFRS with 0.6%~0.8% volume content in tunneling shotcrete could significantly improve flexural ductility, toughness, and ultimate load capacity. Fiber rebounding tests exhibited a low rebounding rate (8.5%) and low Fiber drop (63.5%). Therefore, PAFRS applied to a tunnel exhibited stability and constructability.
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Assessment of flexural toughness and impact resistance of bundle-type Polyamide Fiber-reinforced concrete
Composites Part B: Engineering, 2015Co-Authors: Hongseop Kim, Gyu-yong Kim, Jeong-soo Nam, Nenad Gucunski, Joong Kyu JeonAbstract:Abstract This study compares the Fiber/matrix bonding strength and flexural properties of bundle-type Polyamide Fibers to those of hooked-end steel Fibers. Their fracture behavior upon impact with a high-velocity projectile is also assessed in terms of penetration depth, crater diameter and rear-side scabbing. The results obtained demonstrate that the bundle-type Polyamide Fibers undergo fracture without Fiber pullout because of the increased interFiber gap and specific surface area for bonding, but exhibit poorer flexural fracture behavior with a lower flexural strength and fracture energy when compared to hooked-end steel Fibers. Yet despite this, concrete reinforced with bundle-type Fibers is shown to more effectively suppress scabbing during high-velocity impact, which is attributed to a more efficacious dispersion of shock stress due to the increased number of individual Fibers.
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Effect of Pull-out Property by Shape and Mechanical Property of Reinforcing Fiber on the Flexural Behavior of Concrete
Journal of the Korea institute for structural maintenance and inspection, 2014Co-Authors: Hongseop Kim, Jeong-soo Nam, Jung-hyun Kim, Sang-hyu Han, Gyu-yong KimAbstract:This study evaluated the bonding property of Fiber and flexural behavior of Fiber reinforced concrete. Amorphous steel Fiber, hooked steel Fiber and Polyamide Fiber was used for evaluation of bonding property and flexural behavior. As a result, the hooked steel Fiber was pulled out from matrix when peak stress. However amorphous steel Fiber occurred shear failure because bonding strength between Fiber and matrix was higher than tensile strength of Fiber. Polyamide Fibers occurred significantly displacement to peak stress because of elongation of Fiber. After that peak stress, Fiber was cut off. Amorphous steel Fiber reinforced concrete had a greater maximum flexural load compared with hooked steel Fiber reinforced concrete because bonding performance between Fiber and matrix was high and mixed population of Fiber was many. However flexural stress was rapidly reduced in load-deflection curve because of shear failure of Fiber. Flexural stress of hooked steel Fiber reinforced concrete was slowly reduced because Fiber was pulled out from the matrix. In the case of Polyamide Fiber reinforced concrete, flexural stress was rapidly lowered because of elongation of Fiber. However flexural stress was increased again because of bonding property between Polyamide Fiber and matrix. The pull-out properties of the Fiber and matrix has effect on the deformation capacity and flexural strength of Fiber reinforced concrete.
Hongseop Kim - One of the best experts on this subject based on the ideXlab platform.
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Strain rate effects on the compressive and tensile behavior of bundle-type Polyamide Fiber-reinforced cementitious composites
Composites Part B: Engineering, 2019Co-Authors: Hongseop Kim, Gyu-yong Kim, Sangkyu Lee, Minjae Son, Gyeongcheol Choe, Jeong-soo NamAbstract:Abstract The compressive and tensile behavior of Fiber-reinforced cementitious composites is significantly affected by the bonding and pull-out properties between matrix and reinforced Fiber, as well as the fracture properties of the Fibers. In addition, an increase in strain rate according to loading conditions influences the fracture behavior between the Fiber and matrix. Steel Fiber-reinforced cementitious composites with high flexural and tensile strength, toughness, and crack resistance are widely used in tunnels and plant structures. However, the high specific gravity and stiffness of steel Fibers can cause rupture of concrete pump tubes, increase the rebound volume of shotcrete, and decrease durability by corrosion of Fiber. Therefore, it is necessary to study the development and application of organic Fiber which has similar mechanical properties to steel Fiber and does not cause corrosion. In this study, Polyamide Fibers having the same aspect ratio as the hooked steel Fibers, which are widely used as reinforcing Fibers for concrete, have been developed. And strain rate effect on the compressive and tensile behaviors of bundle-type Polyamide Fiber-reinforced cementitious composite and hooked steel Fiber-reinforced cementitious composite were evaluated. The results showed that the effect of strain rate over different Fiber types influenced the tensile behavior more significantly than the compressive behavior. In Polyamide Fiber-reinforced cementitious composite (PAFRCC), a fracture behavior of Fiber was observed regardless of a strain rate, and the tensile behavior of PAFRCC was influenced more by tensile strength of Polyamide Fiber itself than a bonding stress between Fiber and matrix. In hooked steel Fiber-reinforced cementitious composite (HSFRCC), a bonding stress between hooked steel Fiber and matrix (frictional force at the interface between Fiber and matrix, mechanical bond of the hooked part) influenced the tensile behavior significantly. Fracture properties that straightened pulled out the Fiber from the matrix were observed at static tensile loading condition. However, non-straightened hooked steel Fiber was observed along with the fracture of matrix due to an increase in mechanical bonding force of the hooked part and the bonding stress between the Fiber and the matrix.
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Assessment of flexural toughness and impact resistance of bundle-type Polyamide Fiber-reinforced concrete
Composites Part B: Engineering, 2015Co-Authors: Hongseop Kim, Gyu-yong Kim, Jeong-soo Nam, Nenad Gucunski, Joong Kyu JeonAbstract:Abstract This study compares the Fiber/matrix bonding strength and flexural properties of bundle-type Polyamide Fibers to those of hooked-end steel Fibers. Their fracture behavior upon impact with a high-velocity projectile is also assessed in terms of penetration depth, crater diameter and rear-side scabbing. The results obtained demonstrate that the bundle-type Polyamide Fibers undergo fracture without Fiber pullout because of the increased interFiber gap and specific surface area for bonding, but exhibit poorer flexural fracture behavior with a lower flexural strength and fracture energy when compared to hooked-end steel Fibers. Yet despite this, concrete reinforced with bundle-type Fibers is shown to more effectively suppress scabbing during high-velocity impact, which is attributed to a more efficacious dispersion of shock stress due to the increased number of individual Fibers.
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Effect of Pull-out Property by Shape and Mechanical Property of Reinforcing Fiber on the Flexural Behavior of Concrete
Journal of the Korea institute for structural maintenance and inspection, 2014Co-Authors: Hongseop Kim, Jeong-soo Nam, Jung-hyun Kim, Sang-hyu Han, Gyu-yong KimAbstract:This study evaluated the bonding property of Fiber and flexural behavior of Fiber reinforced concrete. Amorphous steel Fiber, hooked steel Fiber and Polyamide Fiber was used for evaluation of bonding property and flexural behavior. As a result, the hooked steel Fiber was pulled out from matrix when peak stress. However amorphous steel Fiber occurred shear failure because bonding strength between Fiber and matrix was higher than tensile strength of Fiber. Polyamide Fibers occurred significantly displacement to peak stress because of elongation of Fiber. After that peak stress, Fiber was cut off. Amorphous steel Fiber reinforced concrete had a greater maximum flexural load compared with hooked steel Fiber reinforced concrete because bonding performance between Fiber and matrix was high and mixed population of Fiber was many. However flexural stress was rapidly reduced in load-deflection curve because of shear failure of Fiber. Flexural stress of hooked steel Fiber reinforced concrete was slowly reduced because Fiber was pulled out from the matrix. In the case of Polyamide Fiber reinforced concrete, flexural stress was rapidly lowered because of elongation of Fiber. However flexural stress was increased again because of bonding property between Polyamide Fiber and matrix. The pull-out properties of the Fiber and matrix has effect on the deformation capacity and flexural strength of Fiber reinforced concrete.