• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.251-259
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• 2003

In this paper, an analytical approach hwas been conductsed to clarify the relationships between the axial force and the deformation capacity of steel- encased reinforced- concrete beam-columns. The analytical model was defined as a cantilever. Several parameters influencing the inelastic performance of the beam-columns were selected, as follows: including encased steel area ratios, and sectional shapes of the encased steel, material strengths, and shear-span- to-depth ratios. The Analytical results of the analysis showed that the axial force had to have a maximum limit to ensure the stable behavior of a steel- encased reinforced- concrete beam-column when it was subjected to both axial and repeated lateral loading under a constant rotation angle amplitude. The maximum axial force of the beam-column to be resisted under cyclic lateral loading was defined as the stable-limit axial force to ensure the required rotation angle amplitude. The Analytical results of the analysis indicate that the stable-limit axial load ratio increases as the steel strength increases or as the compressive strength of the concrete decreases. The stable-limit axial load ratio decreases as the encased steel ' s sectional area increases in the case of a 1-shaped sections and it is almost not influenced by the steel sectional area in the case of a cross-shaped section.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.431-438
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• 2005

A steel-concrete composite column is a recently developed composite system in which the two opposite flanges of the H-shape section are connected by welded links, and the vacant space enclosed by the flanges, web, and links is filled with concrete. Previous experiments on the SC composite column were performed to evaluate its compression and bending and shear strengths, respectively, and they showed fairly good results. In addition to thesestudies, it may be necessary to evaluate the flexural-axial capacity of an SC composite column, because itscolumn members are generally subjected to axial force and bending moment at the same time. In this study, the bending strength of an SC composite column subjected to axial compression force was investigated experimentally. The results of the study showed that the AISC-LRFD provisions representedexcessively low values compared with those of the ACI, Eurocode-4, and Japan Code provisions. The Eurocode-4 provisions represented reasonable evaluations of the strength of the SC composite column composed of a non-compact section.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.401-409
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• 2005

In this study, reinforced dual concrete beam (RDC beam) composed of steel fiber reinforced concrete (SFRC) in the tension part and normal strength concrete (NSC) in the compression and remaining part is proposed. It is the epochal structural system that improves the overall structural performances of beam by partially superseding the steel fiber reinforced concrete in the lower tension part of conventional reinforced concrete beam (RC beam). Flexural and shear tests are performed to prove the structural excellence of RDC beam in comparison with RC beam. An analytical method is proposed to understand the flexrual behavior and is compared to experimental results. And for shear behavior, experimental results are compared to empirical equations predicting the ultimate shear strength of full-depth fiber reinforced concrete beam to examine the behavior of RDC beam under shear. From this studies, it is proved that RDC beam has more superior structural performance than RC beam, and the analytical method for flexural behavior agrees well with experimental results, and the partial-depth fiber reinforcements have no noticeable effect on ultimate shear strength but it is considerably effective to control and prevent evolutions of crack.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.467-476
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• 2004

Because of crack control by steel bars after cracking the material models for reinforced concrete(RC) differ from those for plain concrete(PL). The nonlinear behavior of columns subjected to lateral load was simulated with reasonable accuracy in 3D analysis by applying distinct material models for RC and PL zone subdivided properly on the section. The shear strain is confirmed to develope unstably with ununiform distribution in out-of-plane direction. And this tendency becomes stronger as the thickness of column member increases in out-of-plane direction. If this ununiformity in strain distribution is not taken into consideration the capacity and the deformability of columns in shear dominant failure are overestimated excessively in two dimensional analysis. By introducing equivalent softening model a behavior of columns can be predicted too in two dimensional analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.95-110
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• 2010

A numerical model to simulate bond-slip behavior of composite beam bridges is introduced in this paper. Assuming a linear bond stress-slip relation along the interface between the slab and girder, the slip behavior is implemented into a finite element formulation. Adopting the introduced model, the slip behavior can be taken account even in a beam element which is composed of both end nodes only. Governing equation of the slip behavior, based on the linear partial interaction theory, can be determined from the force equilibrium and a constant curvature distribution across the section of a composite beam. Since the governing equation for the slip behavior requires the moment values at both end nodes, the piecewise linear distribution of the constant bending moment in an element is assumed. Analysis results by the model are compared with numerical results and experimental values, and load-displacement relations of composite beams were then evaluated to verify the validity of the proposed model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.197-204
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• 2006

This experimental study of prominent section bending behavior beam without shear connector provides bond capacity between concrete profile and initial stiffness of SC beam by comparing the test result with a theological analysis result and an ANSYS(common structural analysis program) analysis result. The compared result provides a fundamental study for practical use of efficient SC beam. Test result indicates 88%-98% rate of theological result in moment capacity and composition ratio shows 30%-70%. In other words, the results are insufficient to make a complete composite action. Therefore, it is need to make pull shear connection of connection method.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.817-822
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• 1994

The reinforcing effect of C-shape carbon fiber was investigated as comparing to typical round-shape fiber with similar properties. The results show that C-shape fiber reinforced materials have better in almost all aspects of mechanical properties, or 218% in flexural strength, 223% flexural modulus, 157% interlamina shear strength, 227% impact strength, 184% transverse flexural strength and so on. Also in damping characteristics considerably concerned with fatigue life, friction/wear coefficient of a material, C-CF/EP had about 185% greater. In this research, we present the potential of non-circular fiber reinforcing materials by C-shape carbon fiber.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.133-142
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• 2013

The shear wall system with coupling beams has been known as an effective means for moderate and high rise buildings up to 40 stories, because this structural system can provide the enhanced lateral stiffness compared to individual shear walls. Typical reinforced concrete coupling beams have difficulties in construction due to complicated reinforcing work on site, and steel coupling beams also have disadvantages in economical point of view because of a large number of stiffeners required for its stability under lateral loading. To overcome these disadvantages in existing coupling beam systems, this study developed the prestressed composite coupling beam with discontinuous webs, which have improved constructability, economic feasibility, and reduced sectional size. The reversed cyclic loading test on two prestressed composite coupling beams with discontinuous webs having different shear reinforcement ratios have been conducted to investigate their structural performances, and test results showed that the proposed composite coupling beams had good seismic performances.

• Journal of the Korean Geotechnical Society
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• v.32 no.7
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• pp.25-34
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• 2016

Recently, in Korea, problems related with unstability of slope or sinkhole in urban area due to erosion of compacted granite soil which was used as a backfill or embankment material have been treated as important issues. Small hole might develop inside of backfill area due to erosion of not only weathered granite soil but also clay, silt, fine sand size particles when underground water flows. Once erosion starts in a soil mass, erosion rate increases gradually to cause rapid destruction. In this study, a rotating cylinder test (RCT) was performed to evaluate the hydraulic resistance characteristics of compacted weathered granite soil under various relative densities and preconsolidation pressures. Meanwhile, an image analysis method was introduced to analyze radius of irregularly eroded sample. It was found that image analysis is an effective means of minimizing the error in calculating a critical shear stress and threshold shear stress on the irregularly eroded sample. Furthermore, in general, hydraulic resistance capacity increases with the increase of relative density and preconsolidation pressure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.454-457
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• 2011

본 논문에서는 국내에서 아직 기준이 마련되지 않은 제진설계에 대한 접근을 소개하였다. ASCE 7-05 기준에 근거하여 국내 5층 규모의 철근콘크리트 신축 건물에 제진 설계를 수행하였다. 우리나라의 현행 기준을 만족하면서 효과적인 제진 시스템 설계를 위한 방법을 소개한다. ASCE 7-05 기준에서는 제진 구조물 해석 시 부재력이 공칭강도의 1.5배를 초과하지 않은 경우 경계비선형 해석을 허용하고 있다. 이 때의 제진 설계 프로세스는 기존의 중력하중 및 등가정적하중의 75%에 의한 단면을 가정하여 부재설계를 실시하고, 선형 시간이력 해석을 통해 제진장치 및 가새를 설계한다. 이후 우리나라 실정에 맞도록 보정된 인공 지진파를 입력하여 경계비선형 해석을 실시하고, 밑면 전단력 및 층간변위 등의 만족여부를 검토한다. 이 때 목표성능을 완전탄성설계 또는 유사탄성설계로 정하여 목표성능을 만족하는지도 검토하여야 한다. 본 논문에 적용한 신축 건물은 유사탄성 설계를 위해 경계비선형 해석을 실시하였고, 가장 효과적인 제진 설계를 위해 댐퍼의 종류, 설치방법, 개수, 변위 증폭비 등을 변수로 한 case study를 진행하였다. 해석 결과 목표성능을 만족하는 범위 내에서 가장 효과적인 제진 설계는 점성댐퍼, 이층 토글형태, 증폭비 2.0, 총 8개의 댐퍼를 설치하는 것으로 나타났다.