• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.327-330
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• 2005

In this study, the nature of brittleness, one of the main problems of GFRP(Glass Fiber Reinforced Plastic) Re-bar, is improved. Therefore, Hybrid GFRP Rod is developed by attaching FBG sensor to the new GFRP Rod with toughness, essential for flexural reinforcement of the concrete. The test was performed with specimens of Hybrid GFRP Rod. According to the test, data measured by electric gauge sensor are compared with data measured by FBG sensor.

• Journal of Korean Association for Spatial Structures
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• v.15 no.1
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• pp.47-55
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• 2015

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.611-616
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• 2002

The concrete beam is quickly required to be replaced or strengthened due to decreasing load carrying capacity. Flexural tests on 3.1m long reinforced concrete beams with carbon-fiber rod are reported. The selected experimental variable is the method of the anchoring beam. The effects of this variable in overall behavior are discussed. This paper considered relation of load-displacement and load-strain. The maximum load was increased to the static behavior of the R/C beam strengthened with CFR rod. The results indicated generally that the flexural strength of strengthening beam was increased. It was required a proper anchorage system and can be led the ductility of beams of a carbon-fiber rod.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.445-452
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• 2012

In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using strengthening materials (embedded FRP rod, metal fittings) in existing reinforced concrete buildings. Seven reinforced concrete beams comprised of retrofitted embedded FRP rod (BCR series), embedded FRP rod with metal fittings (BCR-AC series), and standard specimen (BSS) were constructed and tested under monotonic loading. Design parameters of test specimens were amount of embedded FRP rod and metal fittings. The test results showed that the maximum load carrying capacity of specimens with embedded FRP rod (BCR series) and embedded FRP rod with metal fittings (BCR-AC series) increased by 21~55% and 21~63%, respectively, in comparison with the standard specimen BSS. BCR series test specimens failed by the adhesion slip and concrete cover separation. BCR-AC series test specimens failed by the adhesion slip due to the confining effect of metal fittings.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.181-182
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• 2015

The production technologies of free-form concrete panels are emerging to satisfy the need of modern complex shaped in architectural design. This study aims for introducing and improvising the innovative technique called Rod type mold that overcomes the difficulties in some extent by enabling the mold to be used many times, making the shape of the mold adjustable in a flexible way and describing its production process to provide the alternative solution for the construction of free-form mold with considering the features including reusability and optimization cost across its production process. In this study, the freeform concrete panel shape was designed and experiment was done using computerized numeric control machine and rod type mold. The problems appeared on achieving desired shape while operating on rod type mold. The process of identifying all the root causes and contributing causes that may have generated an undesirable condition were done. Consequently, the conical or semicircular shaped was proposed for the end of Numerical control rod and replaced it with the existing flat shaped end to avoid the detachable problem and to improve rod type mold performance.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.725-730
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• 1998

Recently, non-destructive tests are getting popular in evaluating concrete properties without braking specimens. Among several NDT methods, P-wave velocity measurement technique has been widely used to evaluate the stiffness and strength of concrete. The purpose of this study is to investigate factors influencing P-wave velocity measured by impact-resonant method and ultrasonic pulse velocity method, such as moisture content of concrete, existence and size of coarse aggregates, sensor and sampling rate. Test results show that rod-wave velocity measured by impact-resonant method and ultrasonic pulse velocity are significantly affected by the moisture content of concrete, i.e., the lower moisture content, the lower velocity. Moisture content influences rod-wave velocity stronger than ultrasonic pulse velocity. Rod-wave velocity is faster in concrete than in mortar and is also faster in concrete containing small size aggregates. Sensor and sampling rate have little influence on velocity.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.309-315
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• 2006

Important material properties of UCAS rod can divide by tension characteristic of base rod part and both end part of U type anchor. Tensile properties of base rod part need as concrete reinforcement material as an alternative material of reinforcing rod, and tensile properties of U type anchor is used at connection with UCAS rod. This treatise carry out tensile test of UCAS rod, examine necessary properties such as strength, elastic modulus and maximum capacity of UCAS rod as reinforcement material of concrete. Also, to examine material properties carry out tensile test of U type anchor.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.123-129
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• 2006

Recently, many researches have been conducted about reinforced concrete structures strengthened with FRP plates. In case of structures strengthened with FRP plates, the issue of premature debonding FRP plate has been raised through many previous researches. The purpose of this paper is what structural behavior and flexaural capacity of reinforced concrete beams which are strengthened for flexure is investigated about the using secondary ironware in the method of external bonded CFRP plate, and the method of near surface mounted CFRP-Rod. Also, in order to evaluate flexural capacity, experiments of the reinforced concrete beams with exteranl bonded CFRP plate and near surface mounted CFRP-Rod have been compared and investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.313-318
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• 2002

The use of carbon fiber rods is a promising technology of increasing flexural and shear strength of deficient reinforced concrete members. The purpose of this experimental study is to investigate the fatigue behavior and strengthening effects of the strengthened bridge deck with isotropic and othortropic carbon fiber rod. This study shows a fatigue loading, compliance and S-N Curve between strengthened isotropically and othortropically. Then estimate the effective fatigue behavior of RC slab using composite rods that are inserted in high special purposed polymer mortar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.64-65
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• 2014

Recently freeform buildings which are free from simple shape are implemented depending on improvement of construction method. However, freeform buildings are spent more time and cost to materialize than typical form. Because molds for production of freeform shape cannot be reused. For these reasons, low productivity, delay of construction schedule and budget overflow are occurred. Thus, technology of molds need to be developed for manufacturing of freeform concrete segments. The objective of this study is manufacturing of freeform concrete segments using rod type mold. This technology can implement not only application to various shape but also mass production. Thus, problems of construction period, productivity and cost can be solved. After this study, productivity analysis should be continued through the field application.