• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.56-66
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• 2017

In this study, seismic strengthening performance of RC circular columns reinforced with high ductile PET and hybridized fibers(HF, PET + aramid) strand was experimentally compared and investigated. As a result, the maximum flexural strength and ductility capacity of all reinforced columns were improved than control column and fiber rupture did not occur at the ultimate stage. In addition, the resistive strength and displacement of the PET sheet 25 layers reinforcing column and the HF strand 1 layer reinforcing column were almost similar, so that 1 layer of HF strand showed the same lateral confinement effect as the PET sheet 25 layers. As a result of this experimental study, PET is considered to be suitable as seismic reinforcement material for RC structures in terms of flexural strength and ductility. However, in order to increase the possibility of application in the field, it is necessary to use a prefabricated PET sheet such as HF used in this study. The durability of PET needs investigation in the future.

• Magazine of the Korea Concrete Institute
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• v.6 no.2
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• pp.97-107
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• 1994

The objective of this study is to develop polymer-impregnated concrete(PIC), which is a newly developed composite material made by impregnating polymer impregnanls into hardened normal concrete, and to develop analytical techniques for its proper applications. Crystalline methyl methacrylate(MMA) is chosen as a monomer of polymer impregnants. The corrlpositions of polymer impregnants and producing processes are developed by analyzing the effects of penetration, polymerization, thermal safety, and strengthening characteristics. On t he basis of experimental results of this study, various strength characteristics and stress strain constitutive relations are formulated in terms of the compressive strength of normal concrete and the polymer loadings, which can be applied for analysis and design of PIC members. In order to provide a model for fracture analysis of flexural members, fracture toughness, fracture energy, critical crack width, and tension softening relations near crack tip are also formulated in terms of member depth, initial notch depth, and the flexural strength of normal concrete. The structural analysis procedure and the finite element computer program developed in the study are applicable to evaluate elastic behavior, ultimate strength, and tension softening behavior of MMA type PIC structural members subject to various loading conditions. The accuracy and effectiveness of the developed computer program is examined by comparing the anal ytical results with the experimental results. Therefore, it is concluded that the developed structural analysis procedure and the finite element computer program are applicable to analysis and design of in-situ and precast PIC structural members.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.73-80
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• 1994

This paper is to study the mechanical behavor and structural safety of the wire-mesh half slab by an analytical method. Layer model was adopted by modelling the wire-mesh half slab as a flexural member composed of free cantilever beam and vertical supports (walls or beams). Reasonable results for the prediction of ultimate strength of the half stab at each loading direction and design recommendations for the reinforcement detail at wall(beam)-slab joints are acquired. On the other hand, ductility capacity of the wire-mesh half slab was overestimated by not considering the brittleness of wire-mesh reinforcements pre-manufactured at the form of Kaiser Truss.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.799-804
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• 2002

The compatibility of concrete repairs is proposed by D. Cusson et al. and N. K. Emberson et al. But this is the general compatibility of concrete repairs. This study is actualized the general compatibility of concrete repairs on the flexural specimen under bending load. This study is obtained following results. 1) As a results of analysis for repair effects on failure shape, debonding between concrete and repairs, yielding load and ultimate/yielding ratio, the repair effects is ascertained that the repair R3 is much excellent than the repair R7, but on the other hand R7 is very high than R3 on the viewpoint of compressive strength, where repair R7, R3 is a product. 2) Therefore the compatibility of concrete repair proposed by D. Cusson et al. and N. K. Emberson et al. must be reanalyzed for structures types of column, beam, wall, slab et al.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.176-180
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• 2001

Steel fiber and polymer are used widely for reinforcement material of RC structures because of its excellences of the durability, serviceability as well as mechanical properties. The purpose of this study is investigate the shear behavior of high concrete beams input polymer-steel fibrous. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns and fracture modes. Also, load-strain and load-deflection examined, during the test cracks are sketched the load values according to grow of crack.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.526-529
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• 2006

In this paper, flexure behavior of steel fiber reinforcement ultra high performance cementations composites (SFR-UHPCC) has been analyzed by equivalent stress block. Pulling-out tensile force of steel fiber with concrete matrix was induced. An appropriate flexure evaluation formula, i.e. semi-analytical formula, was established based on rectangular cross section beam for comparing with shear capacity and ultimate load of SFR-UHPCC beam. Finally, the semi-analytical formula has been simplified for the convenience of design work. Experimental results and theoretical shear strength are shown to compare with the formula proposed by this paper. The theory formula has a good prediction of failure type of SFR-UHPCC.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.715-720
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• 1997

In this study, the behavior of R/C beam strengthened with carbon fiber laminate(C.F.L) is analyzed from the test results. Test parameters ar the width and the thickness of C.F.L. The failure mode and ultimate load are analyzed from these measured data. Test results shows that the peak load of specimens strengthened with C.F.L. is increased to 1.27~2.04 times of that of non-rehabilitation specimen. The wider lap width, large amount of rehabilitation materials, the larger strength is obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.851-856
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• 1998

In recent years, glassfibers have been used for strengthening in RC structure because of low material cost and easy repairing work. The purpose of this study is to experimentally and analytically investigate the effect of glassfibers for enhancing the capacity of RC structure. The result shows that yield and ultimate strength of RC beam with glassfibers are increased by approximate 13% and 26%, comparing with those for RC beam without glassfibers. It has been observed from the test that fatigue behaviors of RC beam with glassfibers have been significantly and large improved comparing with those for RC beam without glassfibers.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.255-258
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• 2005

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded prestressed CFRP (Carbon Fiber Reinforced Polymer) strips. A total of 7 specimens have been manufactured of which specimens strengthened with bonded CFRP strips considering the level of prestress as experimental variable, and a specimen with simply bonded CFRP strips. The following phenomena have been observed through the experimental results. The specimen with simply bonded CFRP strips failed below 50$\%$ of its tensile strength due to premature debonding. On the other hand, all the specimens strengthened with prestressed CFRP strips showed sufficient strengthening performance up to the ultimate rupture load of the CFRP strips. Also, it was observed that the cracking loads and yield loads of the strengthened beams were increased proportionally to the prestress level, but the maximum loads were nearly equal regardless of the prestress level.

• Structural Engineering and Mechanics
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• v.24 no.2
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• pp.195-212
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• 2006

In seismic areas, ductility is an important factor in design of high strength concrete (HSC) members under flexure. A number of twelve HSC beams with different percentage of ${\rho}$ & ${\rho}^{\prime}$ were cast and incrementally loaded under bending. The effect of ${\rho}^{\prime}$ on ductility of members were investigated both qualitatively and quantitatively. During the test, the strain on the concrete middle faces, on the tension and compression bars, and also the deflection at different points of the span length were measured up to failure. Based on the obtained results, the serviceability and ultimate behavior, and especially the ductility of the HSC members are more deeply reviewed. Also a comparison between theoretical and experimental results are reported here.