• Structural Engineering and Mechanics
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• 제52권4호
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• pp.843-855
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• 2014

Concrete infill and reinforcement are one of the most well-known strengthening methods of structural elements. This study investigated flexural performance of concrete infill composite PHC pile (ICP pile) reinforced by infill concrete and longitudinal rebars in hollow PHC pile. A total four series of pile specimens were tested by four points bending method under simply supported conditions and investigated bending moment experimentally and analytically. From the test results, it was found that although reinforcement of infilled concrete on the pure bending moment of PHC pile was negligible, reinforcement of PHC pile using infilled concrete and longitudinal rebars increase the maximum bending moment with range from 1.95 to 2.31 times than that of conventional PHC pile. The error of bending moment between experimental results and predicted results by nonlinear sectional analysis on the basis of the conventional layered sectional approach was in the range of -2.54 % to 2.80 %. The axial compression and moment interaction analysis for ICP piles shows more significant strengthening effects of infilled concrete and longitudinal rebars.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.300-307
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• 2006

Integral pile shaft-column foundations are increasingly popular thanks to not only the comparative advantage of economy in constructing large cast-in-drilled-hole(CIDH) piles compared with driven piles with pile cap footings but also being free from problems associated with the critical column-footing connection. In this paper, the structural characteristics of integral pile shaft-column foundations as well as seismic analysis methodology and reinforcement details for seismic design are introduced.

• 한국지반신소재학회논문집
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• 제17권1호
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• pp.111-118
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• 2018

단층 등 취약지반 조건에서의 터널굴착 시 터널천단 및 측벽변위의 억제를 목적으로 하는 각부보강공이 일반적으로 적용되고 있으며, 터널 단면증가 변화율에 따른 각부보강공 설치각도 및 길이를 고려한 지보안전성 확인을 위한 주요 인자로서 내공변위 천단침하 각부침하 각부축력 등의 여러 응력변위 특성 변수들이 있다. 이러한 굴착중 안전성확인을 위한 변수들에 대한 검토 결과, 우각부 침하영향성이 단면증가율 보다 더 큰 변위경향을 보이는 가장 중요한 중점관리 지배요소로 분석되었으며, 터널단면 증가 변화율에 대한 각 보강공 길이별 축력의 변화관점에서는 큰 연관성을 보여주지 못하는 터널단면 증가율 대비 작은 증가율을 나타냈다. 또한, 각부 보강공 축력의 발생경향은 터널 단면증가율보다 보강공 마찰지지 개념 메커니즘에 따른 거동 영향성을 보여주는 것으로 분석되었다. 본 연구결과, 일정한 길이의 각부 보강공이 선정될 경우 지반불량 구간에서의 터널 단면이 다소 대단면화하여도 무리하게 각부보강공의 길이를 연장시키지 않는 것이 시공성 및 경제성을 고려한 보다 더 합리적인 방법으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1132-1139
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• 2010

The steel pipe of steel-concrete composite piles increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, the load-movement relations and the reinforcement effect by the outer steel pipe in the steel-concrete composite pile were analyzed by performing three-dimensional numerical analyses, which can simulate the yielding behavior of pile material and the elasto-plastic behavior of soils. The parameters analyzed in the study include three pile materials of steel, concrete and composite, pile diameter, pile distance and loading direction. As the results, the axial capacity of the composite pile was about 73% larger than that of the steel pipe pile and about 14% larger than that of the concrete pile. In addition, the horizontal movement at the pile head of the composite pile was about 51% of that of the steel pile and about 19% of that of the concrete pile.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 토목섬유 특별세미나
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• pp.61-69
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• 2000

It is not easy to find a good soil condition due to the shortage of suitable land for construction work. The earth structure and buildings can be constructed over the soft soil. The soft soil must be treated either using the reinforcement element or dewatering. Most of land reclamation projects are being implemented along the south coast or west coast of the Korean Peninsula. The soils in these areas are covered with the soft marine clay, so soil and site improvement is the most important things to do. Pile foundation at the bottom of embankment can be constructed either in the soft ground or in the soil contaminated area. The purpose of this research is to develop "geogrid-reinforced piled embankment method" to prevent the differential settlement and increase the bearing capacity of soil. In this study, the effectiveness of the geogrid-reinforcement was studied by varying the space between piles and reinforcement conditions. Also, the geotechnical engineering properties of the embankment material and foundation soil were determined through the laboratory tests as well as the field tests. As a result, the site that the pile-spacing S = 3b with geogrid reinforcement is the most effective to reduce the differential settlement and increase load bearing capacity.

• 토지주택연구
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• 제1권1호
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• pp.67-73
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• 2010

PHC 말뚝에서 강선을 노출시켜 건축물의 기초판과 연결시키는 기존 강선남김 방식은 강결합과 힌지결합의 중간형태로 공동주택(아파트)과 같은 건축구조물에 흔히 사용되는 방법이다. 그러나 이 방법은 역학적인 성능이 검증되지 않았으며 시공과정도 복잡하다. 이에 본 연구는 기존 관련 연구의 결과를 분석하고, PHC 말뚝의 콘크리트 단면적 대비 강선면적 비인 0.3%를 말뚝 접합부의 최소 철근보강량으로 선정하여 PHC 말뚝과 기초판과의 최적의 철근보강 방법을 말뚝 규격별(PHC 450, PHC 500, 및 PHC 600)로 제시하였다. PHC 말뚝과 기초판 접합부의 역학적 성능(인장강도와 전단강도)을 평가하기 위해 실물크기의 실험을 실시하였다. 그 결과, 모든 경우에 대해 요구강도를 만족하였으며 실제 적용되어도 문제가 없음을 확인하였다. 본 결과는 기존 연구에서 제시되었던 접합부의 철근 보강량보다 그 양이 대폭 감소하는 것으로 나타나 PHC 말뚝 시공 시 원가 절감에도 기여할 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.221-224
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• 2005

The purpose of this study is to introduce design practice for transverse reinforcement in piles where the top of the pile is free-standing above the ground in accordance with AASHTO LRFD Design Specification. Based on the relevant requirements, the amount and spacing of transverse spiral reinforcement is given for the two different pile types, namely piles with pile cap and pile bents. In addition, a recommended design procedure is introduced depending on the predicted behaviour of the piles from the analysis.

• Geomechanics and Engineering
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• 제37권5호
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• pp.511-525
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• 2024

Micropiled raft has been used to support the existing and new structures or to provide the seismic reinforcement of foundation systems. Recently, research on micropile or micropiled raft has been actively conducted as the usage of micropile has increased, and the reinforcement effect of pile for the raft, the pile installation methods, and methods for calculating the bearing capacity of micropiled raft have been proposed. In addition, existing research results show that the behavior of this foundation system is different depending on the pile conditions and can be greatly influenced by the characteristics of the upper or lower ground depending on the conditions of pile. In other words, considering that the micropile is a friction pile, it can be predicted that the reinforcing effect of micropile for the raft and the bearing capacity of micropiled raft may depend on the cohesion of upper soil layer depending on the pile conditions. However, existing studies have limitations in that they were conducted without taking this into account. However, existing studies have limitations as they have been conducted without considering these characteristics. Accordingly, this study investigated the reinforcing effect of micropile and the bearing characteristics of micropiled raft by varying the cohesion of upper soil layer and the stiffness of pile which affect the behavior of micropiled raft. In this results, the reinforcing effect of micropile on the raft also increased as the cohesion of soil layer increased, but the reinforcing effect of pile was more effective in ground conditions with decreased the cohesion. In addition, the relationship between the axial stiffness of micropile and the bearing capacity of micropiled raft was found to be a logarithmic linear relationship. It was found that the reinforcing effect of micropile can increase the bearing capacity of raft by 1.33~ 3.72 times depending on the cohesion of soil layer and the rigidity of pile.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1760-1769
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• 2007

The cut slope sliding which has been frequently encountered in Pohang area has been reported due to the rapid reduction of shear strength in mudstone after being exposed to the air. Mudstone has characteristics that it has high enough strength and stiffness in a dry condition, but the strength and stiffness decrease in a wet condition with groundwater infiltration. The case study in this paper shows that mudstone which had enough strength in a boring stage has lost the strength after installing PRD steel pipe pile inducing an insufficient bearing capacity, which has been ascertained by the static load test. Test construction has been performed to investigate the most favorable method for increasing a pile bearing capacity in mudstone with various methods such as MSG (Micro Silica Grouting) around the tip and side of a pile, the perimeter grouting combined with Micro pile reinforcement, and concrete filling after tip reinforcing grouting. From the test construction, MSG has been turned out to be the most favorable method for increasing a pile bearing capacity in mudstone, which has been confirmed by the static load test.

• Structural Engineering and Mechanics
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• 제71권4호
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• pp.363-375
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• 2019

A renewable energy storage pile foundation system is being developed through a multi-disciplinary research project. This system intends to use reinforced concrete pile foundations configured with hollowed sections to store renewable energy generated from solar panels attached to building structures in the form of compressed air. However previous research indicates that the compressed air will generate considerable high circumferential tensile stresses in the concrete pile, which requires unrealistic high hoop reinforcement ratio to avoid leakage of the compressed air. One possible solution is to utilize fiber reinforced concrete instead of placing the hoop reinforcement to resist the tensile stress. This paper investigates nonlinear structural responses and post-cracking behavior of the fiber reinforced concrete pile subjected to high air pressure through nonlinear finite element simulations. Concrete damage plasticity models were used in the simulation. Several parameters were considered in the study including concrete grade, fiber content, and thickness of the pile section. The air pressures which the pile can resist at different crack depths along the pile section were identified. Design recommendations were provided for the energy storage pile foundation using the fiber reinforced concrete.