• Steel and Composite Structures
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• v.16 no.1
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• pp.59-75
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• 2014

A new concrete confinement model is developed to predict the axial load versus displacement behavior of circular columns under concentric axial load. The new confinement model is proposed for concrete filled steel tube columns as well as circular reinforced concrete columns with steel tube jacketing. Existing confinement models were evaluated and improved using available experimental data from different sets of columns tested under similar loading conditions. The proposed model is based on commonly used confinement models with an emphasis on modifying the effective confining pressure coefficient utilizing the strength of the unconfined concrete and the steel tube, the length of the column, and the thickness of the steel tube. The proposed model predicts the ultimate axial strength and the corresponding strain with an acceptable degree of accuracy while also highlighting the importance of the manner in which the steel tube is used.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.206-213
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• 2003

Laboratory testing of representative rock specimens is of fundamental necessity for the successful design and/or assessment of facilities associated with many kinds of underground exploitation, including the geological disposal of radioactive nuclear waste. As a fundamental and systematic study, a series of measurements of the physical, mechanical and hydraulic properties of Inada granite and Shirahama sandstone, two rock types that are widely available in Japan, have been performed. This paper presents the results of a study of the effective porosity, density, compressive and shear wave velocity, unconfined compressive strength and permeability of the two rocks. The anisotropy and the effects of confining pressure on the permeability of the rocks, as well as the relationships among the physical, mechanical and hydraulic properties, are also investigated and discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.151-156
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• 2003

On the basis of the philosophy that "the compressive axial load capacity after spalling of shell concrete should be maintained as that before spalling" by applying the confinement model of high strength concrete proposed in the previous proceeding paper and equivalent lateral confining pressure considering configurations of transverse reinforcement, the amounts of transverse reinforcement from the compressive capacity design method about high strength reinforced concrete tied columns can be calculated through the formula proposed in this paper. The proposed design equation of transverse steel amounts for high strength reinforced concrete tied columns was quite agreeable with the test results of HSC tied columns conducted by other researchers as well as author.as author.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.563-570
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• 2001

In this study, the charactersistics of horizontal drains used to stabilize the dredged fill are investigated experimentally by doing tensile strength test, discharge capacity test, and filter clogging test. The types of the drains selected for the study are filament type (Tyre-E), embossed type(Type-P) and heat bonded cubic type with the thickness 10mm(Type-010) and 5mm(Type-05). The results of tensile strength and discharge capacity test show that the performance of drain Type-O10 was better than the other drains. This is caused by the fact that the lattice shape core of drain Type-O10 has strong rigidity and minimizes the loss of the sectional area of discharge with increased confining pressure. Analyzing the compatibility of filters by the results of the strength characteristics test and clogging test, the filter of filament type drain produced with polyester clothed polyamide performed well.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.87-95
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• 2000

A series of consolidated undrained triaxial compression testes were performed to increase field applications of soil admixtures mixed with short fiber. Kaolin clay and three types of fiber were selected and auto cutter was used to obtain reliable length of fibers. Remolded soil specimens were tested for obtaining the basic data to be applied to the reinforcement of soft clay, embankment or barrier and clay liner of wastes landfill etc. Conversion equations from weight to volume of clay mixed with short fiber are introduced and relationships between fiber content and fiber concentration are derived. It is found that reinforcing effect by aspect ratio and mixing ratio of short fiber decreases as confining pressure increases. The best efficient reinforcing effect is given at the aspect ratio of 80~120 and the fiber content of 1.2%~2.4% and the fiber diameter of 0.27mm.

• Journal of the Korean Society for Railway
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• v.3 no.1
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• pp.34-41
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• 2000

The analysis of static and dynamic characteristics of reinforced roadbed materials was performed through model and laboratory tests. The strength characteristic of reinforced roadbed materials such as HMS-25 and soil were investigated through the unconfined axial compression test, the model soil box test and the combined resonant column and torsional shear test. The unconfined axial compression strength of HMS-25 shows a steady increasement in strength due to the chemical hardening reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects, such as, bearing capacity and settlement. The combined resonant column and torsional shear test result indicates that shear modulus of HMS-25 and soil increase with the power of 0.5 to the confining pressure and linear relationship to normalized shear modulus and damping ratio.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.93-105
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• 2001

해성토층(풍화토 및 모래질 충적토가 암반 위에 쌓인) 위에 준설매립된 수도권 해안매립지역에서 원형의 대심도 굴착공사로 인하여 발생하는 지중연속벽의 수평변위에 대한 현장계측을 중심으로 연구를 수행하였다. 현장측정으로는 지중연속벽의 8방향에서 벽체수평변위와 철근응력, 토압, 간극수압 등이 측정되었고, 정확한 측정결과를 얻기 위하여 합리적인 해석 및 보정방법이 연구되었다. 현장측정결과 굴착시공단계에 따라서 벽체수평변위가 증가하였으며, 일정깊이에 존재하는 점토층을 굴착함으로써 간극수압의 급격한 변화가 측정되었다. 한편, 굴착전후의 구속압감소에 따른 지반물성치의 변화를 정리하였다. 굴착전후의 탄성계수는 일정깊이까지 상당한 정도로 감소됨을 알 수 있었고 굴착전후 여러 가지 시험방법에 따른 탄성계수의 차이들을 비교하였다.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.107-115
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• 2001

해성토층 위에 준설매립된 수도권 해안매립지역에서 원형의 대심도 굴착공사로 인하여 발생하는 지중연속벽의 수평변위를 예측하기 위하여 수치해석을 수행하였고, 이러한 수치해석결과와 현장측정값을 비교하여 각각의 수치해석방법의 적용성을 평가하였다. 수치해석법으로는 지반반력해석, 선형 유한요소법 그리고 비선형 유한요소법이 수행되었다. 각각의 방법들에서는 미소변형률에서의 지반거동특성인 비선형성과 굴착으로 인한 구속압감소효과를 고려한 경우와 고려하지 않은 경우에 대하여 수치해석을 수행하여 각각 그 결과들을 비교.분석하였다. 이러한 분석결과 미소변형률에서의 비선형성과 굴착으로 인한 구속압감소 효과를 고려한 비선형 유한요소해석법이 가장 정확하게 수평변위를 예측할 수 있는 방법임을 알 수 있었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.75-82
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• 2000

A huge offshore structures such as immersed tunnel, ice-resisting wall are continuously subjected to large force from water pressure, wave action and impact loads. Composite steel-concrete structure of sandwich system has profitable advantages for a huge offshore structures. This composite structures should exhibit a high degree of strength and ductility, because of concrete confining effect and the property of steel plate. Therefore, it endures large deformation and absorbs a great deal of energy until failure. In this study, nonlinear analysis for composite steel-concrete structure of sandwich system was carried out, and certify the effects of various parameters, elastic·plastic behavior characteristic, load-carrying and failure mechanism.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.291-294
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• 2008

A ICH-CFT colunn(internally confined hollow-concrete filled tube column) has many advantages compare with R.C column and CFT column. For example using a hollow section, it is possible to save material and to reduce self weight of column. Also two steel tubes on both sid of concrete, inner and outter tube, can improve ductility of ICH-CFT column. But study about ICH-CFT section has done only theoretically. Thus although ICH-CFT column has many advantages, ICH-CFT column dosen't use in construction. In this thesis, through out 3-D full modeling using ABAQUS analyze the nonlinear behavaior of ICH-CFT column. And using the analysis result, review the theoretical knowledge.