• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.203-212
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• 2008

The cyclic behavior and energy dissipation mechanism of short coupling beams with various reinforcement layouts were studied. For numerical analysis of coupling beams, nonlinear truss model was used. The results of numerical analysis showed that the coupling beams with conventional reinforcement layout showed pinched cyclic behavior without significant energy dissipation, whereas the coupling beams with diagonal reinforcement exhibited stable cyclic behavior without pinching. The energy dissipation of the coupling beams was developed mainly by diagonal reinforcing bars developing large plastic strains rather than concrete which is a brittle material Based on this result, simplified equations for evaluating the energy dissipation of coupling beams were developed. For verification, the predicted energy dissipation was compared with the test results. The results showed that the simplified equations can predict the energy dissipation of short coupling beams with shear span-to-depth ratio less than 1.25 with reasonable precision, addressing various design parameters such as reinforcement layout, shear span-to-depth ratio, and the magnitude of inelastic displacement. The proposed energy equations can be easily applied to performance-based seismic evaluation and design of reinforced concrete structures and members.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.557-569
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• 2011

Steel Fiber Reinforced Concrete (SFRC) is widely used for tunnel structures such as shotcrete and segments. Corrosion of steel fibers and steel reinforcements may affect on the long-term durability of the concrete structures with steel fibers and reinforcement. Therefore, a study on the feasible method to evaluate corrosion possibility and permeability of the concrete structures is required. This experimental study examines the effect of steel fibers and internal reinforcement on the surface resistivity. Steel fiber mix ratio and corrosion of internal reinforcement were considered as variables. In the results, steel fibers significantly reduce the surface resistivity due to those conductive characteristic. In the case of 3% mix ratio, it was difficult to evaluate rate and permeability of corrosion due to the great reduction of resistivity by mixing of steel fibers.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.129-136
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• 2012

Compression splices are required for all compression members in almost all of the floors in high-rise buildings. Therefore, a clear understanding of the behavior of compression splices can provide a rational design of compression splices. Tests of compression splices with bearing only and bond only cases were conducted to investigate the component resistance characteristics of compression splices. Test results showed that the circumferential tensile stresses induced by bearing and bond overlapped at the end of the splice length deterred bond and bearing splices from developing target splicing strength when both normal bond and bearing splices were used. In particular, the bearing strength was more significantly reduced than the bond strength since the bearing relied on the limited area near the end of the splice length. However, the strength of the normal splice was always higher than the strength of the bond only or the bearing only case. Consequently, the study results showed that splice strength in compression cannot be improved by means of removing bond or bearing. In addition, the bond strength in bond only splices was nearly same as the bond strength in tension splices and the strength increase of compression splice is attributed to end bearing only characteristic.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.63-70
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• 2010

The purpose of this study is to investigate experimentally the behavior of unreinforced masonry RC frames strengthened by CFRP sheet under cyclic lateral loading. Four test specimens were constructed as one-story, one-bay, 1/2 scale unreinforced masonry infilled RC frames and differences in strength and stiffness were evaluated in specimens on which had been applied different retrofitting methods. Test results indicated that the CFRP sheets significantly increased the strength and stiffness of the specimens, and the specimens retrofitted in columns and masonry indicated the most adequate retrofitting methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.1-12
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• 1993

Four series of fiber reinforced concrete beams without shear reinforcement were tested to determine their cracking shear strengths and ultimate shear capacities. Results of tests on 36 reinforced concrete beams (including 21 containing steel fibers) are reported. Four parameters were varied in the study, namely, the concrete compressive strength, volume fraction of fibers, shear span-to-depth ratio, and the tensile steel reinforcement. The effects of fiber incorporation on failure modes, deflections, cracking shear strength, and ultimate shear strength have been examined. Resistance to shear stresses have been found to be improved by the inclusion of fibers. Based on these investigations, a method of computing the shear strength of steel fiber reinforced concrete beam is suggested. The comparisons between computed values and experimentally observed values are shown to verify the proposed theoretical treatment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.433-436
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• 2010

본 논문에서는 파일형 선박충돌 방호공에 선박이 충돌하였을 때 방호공의 거동을 해석하였다. 방호공의 구조는 상부슬래브, RCP 말뚝 및 이를 지지하는 지반은 비선형 지반스프링으로 모델링 하였다. 상부슬래브 8절점요소로 모델링 하였으며 철근과 콘크리트로 구성되어있다. RCP 말뚝은 철근망과 충진콘크리트로 구성되어있으며 충돌 시 파괴거동을 표현할 수 있는 Damaged Plasticity로 모델을 사용하였고 Shell 요소로 모델링 하였다. 선박충돌 시 선박의 강성에 따른 거동 특성을 파악하기 위해 선박을 강체모델과 실제모델에 대한 해석을 수행하였다. 선박과 교량의 충돌은 정면충돌로 고려하였으며, 충돌속도는 3.3m/sec로 가정하였다. 선박과 방호공과의 충돌 해석은 비선형 해석 프로그램인 ABAQUS/Explicit을 이용하여 수행하였으며, 이를 통하여 선박 충돌 시 방호공의 에너지 거동을 분석하였다. 해석결과 선박의 강성이 커질수록 슬래브의 변형 및 소산 에너지량이 커지는 것을 확인할 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.193-195
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• 2011

Nowadays, climatic environment change has become a major issue in the world. This causes major emissions of carbon dioxide industries steel industry, thermal power industry, cement industry is essential in the reduction of carbon dioxide, which is based on total carbon dioxide emissions account for most of the construction industry in an effort to minimize the environmental load is needed. accordingly, through case studies, It can be induce the selection to minimize environmental load by comparing the output of quantitative energy consumption and carbon dioxide emissions per constructional methods. As a result of this study, RC Structure was less environmental load than SC structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.285-287
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• 2012

염해는 철근 콘크리트 구조물의 주요 열화원인으로서 특히 수해양 부유식 건축물의 상부구조는 비래염분에 의한 피해에 노출되어 있고, 해수에 접하고 있는 함체는 다공질 콘크리트의 모세관으로 염수이온이 침투하므로 상당히 높은 수위의 열화 환경에 노출되어 있다고 분류할 수 있다. 본 연구는 해양에서 유입되는 비래염분량을 정량화하여 철근 콘크리트 구조물 뿐만아니라 강재 건자재의 장수명화를 꾀하는 기초자료를 구축하고자 하였다. 1년간에 걸쳐 측정된 비래염분유입 지역은 기존연구에서 조사된 1km 범위을 상당히 초과하고 있으며 그 량도 강재 발청농도를 탁월하게 상회하는 것으로 분석되었다.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.29-37
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• 2002

The purpose of this study is to provide a fundamental data of earthquake resistant design through the estimation of the response modification factor and nonlinear displacement for moment resisting reinforced concrete frames by linear and nonlinear static analysis. The analysis models are designed in accordance with AIK code and then, estimated the response modification factor and nonlinear displacement of the buildings. The parameters such as story numbers(10, 20, 30), plan ratios(1:1, 1:2) and analysis types(2D, 3D) of building structure are chosen for use in this study. After comparing the results of linear and nonlinear static analysis, the response modification factor is obtained as the product of four factors: ductility factor, strength factor, damping factor and redundancy factor. The response modification factor are close to 3.5 in case of 2 span, 4.3 in case of 3 span and 5.0 in case 4 or more span models regardless number of stories and plan ratios. The nonlinear displacement is evaluated from the ratio of story drift angle(nonlinear drift/linear drift). The ratio of story drift angle increases as story numbers increase and the value varies from 5.85 to 9.34.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.117-133
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• 2010

A hybrid system of soil-nailing and compression anchor is proposed in this paper; the system is composed of an anchor bar (installed at the tip) with two PC strands and a steel bar. After drilling a hole, installing proposed hybrid systems, and filling the hole with grouting material, prestress is applied to the anchor bar to restrict the deformation at the head and/or to prevent shallow slope failures. However, since the elongation rate of PC strand is much larger than that of steel bar, yield at the steel bar will occur much earlier than at the PC strand. It means that the yield load of the hybrid system will be overestimated if we simply add yield loads of the two - anchor bar and PC strands. It might be needed to try to match the yielding time of the two materials by applying the prestress to the anchor bar. It means that the main purpose of applying prestress to the anchor bar should be two-fold: to restrict the deformation at the nail head; and more importantly, to maximize the design load of the hybrid system by utilizing load transfer mechanism that transfers the prestress applied at the tip to the head through anchor bar. In order to study the load transfer mechanism in a systematic way, in-situ pullout tests were performed with the following conditions: soil-nailing only; hybrid system with the variation of prestress stresses from 0 kN to 196 kN. It was found that the prestress applied to the anchor system will induce the compressive stress to the steel bar; it will result in decrease in the slope of load-displacement curve of the steel bar. Then, the elongation at which the steel bar will reach yield stress might become similar to that of PC strands. By taking advantage of prestress to match elongations at yield, the pullout design load of the hybrid system can be increased up to twice that of the soil-nailing system.