To overcome the weakness of spread foundation in large space structure, the research of precast pile for replace spread foundation have been conducted. The new type of joint between PHC pile and steel column is named HAT Joint(Hollow hAlf-sphere cast-sTeel Joint). It connected PHC Pile by bolt that verification of bolt connection should be accomplished. In this paper, pull-out test and flexural performance for HAT Joint to verifying the bolt connection is explained. As a result, the pull-out and flexural capacities of bolt were checked to use in real structure. Furthermore, the equation of pull-out strength was proposed.

This paper presents a foundation pile to steel column connection that can resist large magnitude of moment and that can be easy installed. The developed joint has spherical shape and it is given the name HAT joint to mean Hallow half-sphere steel joint. Four types of HAT joints are developed. Namely, H-type, T-type, P-type and K-type. In this paper I will talk about the performance assessment of T-type(Tube Column) and P-type(Pile Column) of HAT joints with finite element analysis and experiment on a full scale model is presented.

In Part I, we disccussed of joint between PHC pile and steel column in foundation of large space structures, one prototype of a joint of PHC pile to steel pipe column was suggested on the basis of analytical studies. In this paper, I explain the Joint of PHC pile to steel tube column and more detail of analysis

To overcome disadvantages of usual spread foundation in large space structure, some prototypes of a joint of the PHC pile to steel pipe column that directly connects a column to a PHC pile are analytically studied. With the consideration of strength requirement and stress concentration of joint of the PHC pile to column, we suggest the most appropriate one.

This study introduces the result of dynamic tests carried out for the field application of ferro-nikel slag powder applied PHC PILE. For the test, a high strength, ultra high strength FNS PHC PILE was used as a test body, and a PHC PILE with a diameter of 600mm and a length of 20m was applied.

Recently, the demand for large diameter piles has been rapidly increased in order to secure the allowable bearing capacity of pile foundation due to the increase of large structures such as high rise buildings. In this study, to improve the shear capacity of a conventional PHC pile, a large diameter composite PHC pile strengthened by in-filled concrete and shear reinforcement was manufactured. All the piles were tested according to the shear strength test method of Korean Standard. As a result of the shear test, the F-type piles which are produced without shear reinforcement occurred abrupt horizontal cracks after flexural and inclined shear cracks occurred. On the contrary, the FT-type piles which are produced with shear reinforcement exhibited stable flexural and inclined shear cracks uniformly over the entire pile without abrupt horizontal cracks. Furthermore, the maximum load of the large diameter composite PHC pile improved to 2.9 times in the F series, and more than 3.3 times in the FT series compared to the conventional PHC pile. This result indicated that FT-type piles had excellent composite behavior due to the shear reinforcement and effectively prevented the unstable growth of inclined shear cracks.

최근 구조물의 대형화에 따른 큰 지지력의 말뚝에 대한 수요가 증가하는 추세이다. 이에 따라 기성 PHC말뚝의 경우에도 700~1,200 mm 범위의 대구경 말뚝에 대한 활용이 증가하고 있고 최근 국내 현장에 적용되고 있다. 이 연구에서는 대구경 PHC말뚝의 휨성능을 향상시키기 위 해 철근과 콘크리트로 보강하여 합성 PHC말뚝을 제작하였다. 휨강도 평가는 4등분점 제하실험을 통해 변위제어 방법으로 수행되었다. 휨실 험을 통해 LICPT 실험체 횡방향 철근의 변형률 분포를 분석한 결과 횡방향 철근의 배근은 전단균열의 진전과 균열폭 제어에 효과적인 것으로 나타났고, 복부전단균열 발생을 억제할 수 있었다. LICPT 실험체는 LICP 실험체 보다 휨강도가 약 1.08배, 중앙부 변위가 약 1.19배 증가하였 고, 횡방향 철근의 배근은 말뚝의 연성적인 휨거동 확보에 유리한 것으로 나타났다. 말뚝 제작시 사용되는 각각의 재료가 휨강도에 기여하는 수준을 층상화 단면 해석으로 계산된 축강도-휨모멘트 상관도를 통해 평가하였다. 기성 PHC말뚝과 LICP 실험체의 실제 휨강도를 1.13배, 1.16 배의 안전율로 예측할 수 있었다.

말뚝머리-확대기초 접합부는 상부구조물의 하중을 말뚝으로 전달하는 연결부분으로서 부재의 단면과 강성의 급격히 변화하는 부 위이기 때문에 응력이 집중되고 작용하는 휨모멘트와 전단력이 큰 취약부분이다. 이 연구에서는 제작조건에 따른 PHC말뚝 및 합성 PHC말뚝 과 확대기초 접합부의 구조성능을 평가하는데 목적이 있다. 반복가력 하중 조건하에서의 균열패턴, 하중-변위관계, 연성비, 초기 회전강성 및 에너지소산 특성을 각각 평가하였다. 접합부 초기 회전강성은 확대기초 내부로 삽입되는 말뚝삽입 깊이와 축방향철근 배근위치에 큰 영향을 받는 것으로 나타났다. 또한 접합부 강도, 연성비 및 누적 에너지소산 등의 접합부 거동은 말뚝의 종류와 축방향 철근 배근 위치에 영향을 받는 것으로 나타났다.

The study is compressive strength of 110MPa PHC pile using ground granulated blast furnace slag to NAC, AC curing method. In the result, 20% of ground granulated blast furnace slag could be substituted for cement in PHC pile concrete.

This study developed the Anti-Floating Method using PHC Pile adapting to the Underground Structures. This Method fixed the wedges on the P.C. strands of the PHC Pile to reinforce the adhesion strength in the concrete foundation. Pullout test result showed 2~3 times better than the present method, so the developed method can be used as the Anti-Floating Method of underground structures.

This study was performed to analyze the flexural performance of large diameter PHC Pile reinforced with transveres and longitudinal rebar and in-filled concrete. From the flexural test result, it was found that the initial cracking strength and maximum flexural strength of composite PHC pile were approximately 400% and 345% higher than that of the conventional PHC pile.

The study on physical properties of PHC pile and pile filler using blast furnace slag were evaluated. In the results, it was found that compressive strength and workability of PHC pile concrete with 20% of blast furnace slag adjusted S/a 27% were satisfied with desired properties and it was available to improve flow and compressive strength of file filler with 35% of blast furnace slag and TG as additive.

근래 들어 구조물이 대형화 및 장대화되고, 건축물의 고층화와 기둥식 구조의 증가로 인해 기초는 과거보다 상대적으로 큰 연직지지력 또는 수평지지력이 요구되고 있으며 말뚝 시공 장비의 발달과 대형화로 중,대구경 말뚝의 수요가 급격하게 증가하고 있다. 그 중에서도 PHC PILE은 국내에 도입된 이후 기존 PC PILE을 급속하게 대체하여 왔으며, 초창기에 중구경을 많이 사용하여 왔으나 차츰 대형화되어 현재는 Ø700∼1,200까지 사용하고 있는 상황이다. 본 연구과제는 실제 현장에서 적용한 대구경 PHC PILE을 시공한 사례를 중심으로 공법 특징, 장단점, 시공성 및 경제성등에 대해 연구한 내용이다.

Recently, new cities of Korean coastal area, connective land·bridge and marine structure are increased. However, actually the evaluation method of pile head strengthening performance is not clearly defined, and, in spite of many technology proposed, its qualitative evaluation is not made. Therefore, the fact is that the prefabricated pile head strengthening stability is not verified. Therefore, it’s necessary to evaluate various technologies strategically and verify safety of precast file’s cap.

In this study, from the material properties of the aggregates into the actual applications were evaluated for utilizingthe air-cooled blast furnace slag as the coarse aggregates (SG) in PHC piles. The physical and chemical characters ofthe SG were satisfied the standards presented in KS F 2544 for concrete blast furnace slag aggregates. And it was satisfiedthe environmental-factor-evaluation, including the soluble, heavy metal elution and total mercury content, and etc. In casethe non-washed type SG is used, the S/A ratio adjustment according to micro-powder of the aggregate surface and chemicaladmixture adjustment are needed in order to satisfy the aimed material properties. As the replacement ratio of SGincreased, the manifestation rate of compressive strength of the PHC piles was decreased. Particularly, in case non-washingtype SG, the manifestation rate more decreased. Therefore, the elimination of the pop-out materials and cleaning processare necessary for the production process for using the SG as coarse aggregates of PHC Piles

The purpose of this study is to evaluate the flexural strength of the concrete-infilled composite PHC (hereinafter ICP) pile which is the PHC pile reinforced with infilled concrete, transverse and longitudinal reinforcement for the improvement of flexural strength. In addition, an analytical study, which evaluated the flexural strength of the ICP piles depending on the reinforcement using the fiber section analysis was performed.

The purpose of this study is to evaluate the axial compression(P) - bending moment(M) interaction of PHC pile reinforced with infilled concrete and rebar. A type of 500-80t PHC pile was used for evaluating P-M interaction. From the result, the P-M of PHC pile reinforced with infilled concrete and rebar was evaluated approximately 24% and 64% higher than that of conventional PHC pile respectively.