• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.233-234
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• 2017

본 논문에서는 콘크리트 구조체의 단면 손실에 의한 내력 저하 및 보수용 모르타르에 의한 개선효과를 확인하고자 하였다. 이를 위하여, 모르타르와 콘크리트의 각종 강도 특성을 파악하여 비교 검토하여 연구하였다.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.95-104
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• 2006

For the interests in the economical and safe design of foundation system, the concern on the piled raft or disconnected piled raft foundation system is increasing now. In this study, the behavior and the effects of the disconnected piled raft foundation not studied actively in this country were examined using the triaxial compression tests in place of laboratory model tests. The triaxial test samples were prepared with Jumunjin standard sand and the carbon rods, which simulate the ground soil and piles respectively. After the sample in which carbon rods were arranged was laid inside the triaxial chamber, the confining pressure was applied and then loading test was conducted. To analyze the reinforcing effects of the disconnected piled raft foundation, a few number of tests were carried out by changing the number, the diameter and the length of the model piles. As a result of this study, in the disconnected piled raft foundation system, even though the number of pile is few and the diameter of pile is small, the settlement of the foundation system decreased greatly.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.153-161
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• 2010

Numerous past studies have shown that safety and serviceability of many concrete infrastructures and buildings built in 1970's have far less strength capacities than their original intended design capacities, thereby requiring repair and strengthening. Currently, aged concrete structures are being repaired using various methods developed in the past. Unfortunately, these methods do not consider the specific conditions that these members are under, but they merely attach repairing materials on the external surface for random strength improvements. Therefore, in order to improve repair and strengthening methods by considering composite behavior between repairing material and structural member, enhanced construction methodologies are needed. Also, the enhanced repairing and strengthening methods must be able to be implemented on structural members constructed using high performance concrete to meet the present construction demand of building mammoth structures. Therefore, in this study, a repairing and strengthening method for retrofitting high strength concrete (HSC) columns that can effectively improve column performance is developed. A square HSC column's cross-sectional shape is converted to an octagonal shape by attaching precast members on the surface of the column. Then, the octagonal column surface is surface wrapped using Carbon Fiber Sheets (CFS). The method allows maximum usage of confinement effect from externally jacketing CFS to improve strength and ductility of repaired HSC columns. The research results are discussed in detail.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.207-215
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• 2014

As a reinforcement material for RC members, the modified epoxy mortar has been reported one of the superior materials since the material can improve the load capacity and the seismic performance of the RC members. However, there were few experimental studies and analytical research for improving seismic performance with the material. This study is to propose an effective reinforcement plan for RC Ordinary Moment Resisting Frame (OMRF) with the evaluation of seismic performance and economic analysis. For the objective, first, the load-deflection curve of a simple beam specimen was compared with the analytical results. Second, a 5-story RC OMRF structure was designed only for gravity load and the alternatives for seismic reinforcement were suggested. Third, pushover analysis was executed for evaluation of design coefficients and seismic performance of the structures. Finally, an effective reinforcement plan was suggested based on the results of quantity take-off and economic analysis. The findings of this study can be utilized as the basic data when the modified epoxy mortar is applied to practice for improving the seismic performance of RC members.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.175-186
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• 2006

Strength method for determining nominal moment capacity of reinforced concrete members is also assumed to be suitable for strengthened members with FRP system. If the internal tensile forces of the strengthened member from steel and FRP is insufficient, the FRP system strain might become greater than its ultimate tensile strain which makes the strength method a contradiction and unapplicable. The experimental results of 27 strengthened beams with carbon fiber sheets which have relatively lower tensile forces from steel and FRP show that not only concrete compressive strain is lower than 0.003 but also measured ultimate moment was lower than nominal moment using the strength method.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.43-50
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• 2010

To address the problems caused by the corrosion of steel rebar, active research has recently been carried out on members where fiber-reinforced polymer (FRP) is used in place of rebar. As FRP bar is highly brittle and has a low modulus of elasticity, further research is needed on the evaluation of serviceability, in other words on the deflection of flexural concrete members reinforced with FRP rebars. Taking the reinforcement ratio as a variable, this paper analyzes the flexural capacity of concrete beams reinforced with CFRP rebar. The test results of specimens reinforced with CFRP rebar show an increase in stiffness and resisting force along with an increase in the reinforcement ratio. A reinforcement ratio of about 1.3 is needed for the member reinforced with CFRP rebar to show same section property of a steel member. Through a comparison for the value of an effective moment of inertia, the equation suggested by Bischoff & Scanlon predicted values closest to the actual results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.390-397
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• 2014

BO-105 helicopter applies hingeless rotor hub system and blade root uses a flexure of hingeless rotor hub system. So bending stiffness reinforcement for flexure was conducted for preparation of whirl tower test using BO-105 blade. Bending moment of flexure area was calculated with FE modeling of section shape for stiffness reinforcement of flexure and thickness of composite material for reinforcement was chosen. Flexure bending stiffness reinforcement was conducted and bending stiffness measurement test was performed before and after bending stiffness reinforcement. And the test data are compared with analysis results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.106-114
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• 2009

The basis principle of conservation about deterioration and corrosion of cultural assets building is the archetype maintenance, and should not make a factitious damage mistake by repair. Accordingly, conservation processing method using synthetic resins is embossed. The purpose of this paper is about flexural capacity of rectangular section wood using synthetic resins, the 11 specimens are manufactured and made an experiment about reinforcement length, ratio, material strength, direction of synthetic resins as variable. The results of this paper has shown that flexural reinforcement of wood by synthetic resins are efficient and found the possibility of using.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.185-191
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• 2008

To fundamentally solve the problem of deterioration of concrete structures, it has been researched that the high durable concrete structure reinforced with the FRP rebar can be one of major solution to the newly-developed concrete structure. FRP rebar has lots of advantages such as non-corrosive, high performance and light weight against the conventional steel rebar. Among these kinds of FRP rebars, GFRP rebar has usually been considered as the best reinforcement because of its economic point of view. Even though the material capacity of the GFRP rebar was already investigated, there are some problems such as low modulus of elastic that will be cause for degrade of the serviceability of flexural concrete member reinforced with the GFRP rebar. Thus, the deflection characteristics of the GFRP rebar reinforced concrete structure should be considered then investigated. In this study, ACI 440 guideline (2003), ISIS Canada Design Manual (2001) and Toutanji et al. (2000) was considered for predicting the moment of inertia of the concrete beam reinforced with the GFRP rebar. And it was also evaluated that load-deflection relationship had a good accordance with the test and analysis result. In the result of this study, it could be estimated that the load-deflection relationship using the suggested equation of moment of inertia in this study indicated better accordance with the test result than that of the others until failure.

• Journal of Korean Society of Steel Construction
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• v.28 no.3
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• pp.185-194
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• 2016

This paper presents the finite element method results for HSS(Hollow Square Section) steel columns strengthened with Carbon Fiber Reinforced Polymer Plastic(CFRP) sheets. 6 specimens were fabricated and the specimen groups were non-compact short columns, slender short columns, and non-compact long columns. Test parameter was the number of CFRP ply. The finite element analysis was performed by using ANSYS Workbench V.14.0 and the results of FEM were compared with those of Test for failure mode, load-displacement curve, maximum load, and initial stiffness. The comparisons between experimental observations and computed results show that the analyses provided good correlation to actual behavior. Finally, the buckling stress were calculated according to the AISC cold-formed structure provision and the retrofitting effect were verified for each section type.