• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.191-200
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• 2006

The micropile, which is a kind of the in-situ manufactured pile with small diameter of 100~300mm, is constructed by installing a steel bar or pipe and injecting grout into a borehole. The application fields of micropile are being gradually expanded in a limited space of down-town area, because the micropile has various advantages with low vibration and noise in method and compact size in machine, etc. Mostly, the micropile has been applied to secure the safety of structures, depending on the increment of bearing capacity and the restraint of displacement. The micropile is expected to be used in various fields due to its effectiveness and potentiality in the future. The model test, focused on the interaction between micropile and soil in this study, was carried out. The micropile is installed under footing(concept of "structure supporting"). With the test results and soil deformation analysis, the reinforcement effect(relating to bearing capacity and settlement) was analysed in a qualitative and quantitative manner, respectively. Consequently, it is hoped to demonstrate the improvement of an efficiency and application in the design and construction of micropile.

• Journal of the Korean Geotechnical Society
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• v.40 no.2
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• pp.41-53
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• 2024

Micropiles are small, cast-in-place piles with a diameter of 300 mm or less, primarily used to reinforce existing structures and support new constructions. As the application of these piles has expanded, extensive research has been conducted on their bearing characteristics, particularly in micropiled rafts. These studies have consistently demonstrated the positive impact of micropiles on foundation reinforcement. However, previous research often overlooked the potential variations in behavior between micropiled and conventional piled rafts based on different pile conditions. Furthermore, the influence of the cohesive characteristics of the soil layer beneath the foundation on the reinforcing effect of the micropiles has not been adequately addressed. This study, therefore, undertook 3D numerical analysis to assess the reinforcing effect of micropiles, considering both pile conditions and the cohesive characteristics of the soil layer beneath the foundation. The findings revealed that micropiles are significantly more effective in non-cohesive soil layers compared to cohesive ones, with the potential to increase the bearing capacity of the raft by up to 3.7 times.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.85-92
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• 2014

Structures that have constructed in soft clay might suffer from many issues related to consolidation settlement or lateral movement of soft-clay during long-term period. Therefore, it is important to establish proper design and construction processes related to site investigation, soil improvement, construction management, and so on. This case study focused on the construction of the rahmen structure supported by pile foundations. Especially, the structure in this case had been constructed without improving underlying soft clay and before constructing backfill embankment due to the limited construction time and the traffic connection of the old road crossing new highway. Therefore, in order to satisfy the structural stability, the construction processes and countermeasure methods were carefully planned based on the results of preliminary numerical analyses and monitoring of ground behaviors. Through the trial and error precess during the construction, the structures had been successfully constructed.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.13-25
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• 1997

전 세계의 대형 저속 디젤 엔진을 설계.제작하는 회사는 1980년대에 들어오면서 MAN - B&W, SULZER, MITSUBISHI의 3파전 양상을 띠고 있으며, 세계 시장점유율에서는 MAN - B&W가 50%이상을 차지하고 있다. 한국은 현재 한국중공업, 현대중공업, 쌍용중공업 및 삼성중공업에서 대형 저속 디젤 엔진을 생산하고 있다. 국내에서 생산되고 있는 대형 저속 디젤 엔진은 대부분이 MAN - B&W형이고 SULZER형이 약 20%를 차지하고 있다. 기술력은 위의 3사에 거의 의존하고 있으며, 설계보다는 생산에 치중하고 있는 실정이다. 선박용 엔진 구조물은 베드 플레이드(bed plate), 실린더 프레임(cylinder frame), 프레임 박스(frame box)등이 주 스테이 볼트(long stay bolt)에 의하여 체결되어 한 개의 대형 수직 구조물을 이루고 있으며, 프레임 박스의 안내면(guide plate)과 베드 플레이트의 베어링 지지부(bearing support)등은 엔진의 폭발력과 선박의 추진력을 직접적으로 받으므로 구조적 결함과 하자 보수의 문제들이 발생하고 있다. 이와 같은 사용상 및 제작상의 제문제를 해결하기 위해서는 유한요소 구조 해석 능력을 자체 보유하여 구조 설계상의 문제점을 분석하고 엔진 구조물의 취약 부위를 집중 검토하여야하며, 이를 통해 선박의 운항 중에 일어날 수 있는 사고를 미연에 방지할 수 있다. 그러나 국내에서는 이러한 대형 엔진 구조물의 설계/해석 기술이 거의 없고 구조적 문제점이 발생할 경우에는 모든 사항을 설계사(licensor)에 전적으로 의존하고 있는 실정이다. 한편, 설계 기술을 보유하고 있는 MAN - B&W, NEW SULZER DIESEL사 등은 정밀 구조 해석을 통하여 기존 엔진 구조물에 대한 안전성 및 신뢰성을 높임과 동시에 신 모델 개발에 박차를 가하고 있으나, 기술 이전은 회피하고 있어 대형 엔진 구조물에 대한 구조 해석 기술의 개발이 시급하다고 할 수 있다. 본 해설에서는 CAD/CAE(Computer Aided Design/Computer Aided Engineering)를 이용하여 위에서 제시된 대형 엔진 구조물의 구조해석 절차와 방법에 대해 간략히 설명하고자 한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.181-190
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• 2005

In the conventional outrigger system, the outriggers are located in the planes of the core walls and this system has disadvantage of obstructing flexibility in the interior layout. But thc facade riggers in the structure uc located In the exterior frames in the direction of the lateral loading. The interaction between the traced frames and facade riggers is through the floor diaphragms adjacent to the chords of the riggers. This paper presents an approximate analysis technique lot preliminary analysis of multiple facade rigger stiffened braced frames in tall buildings subjected to uniformly and triangularly distributed loads as well as a lateral point load at the top of the structure. Comparisons with the results by the program MIDAS for the structural models have shown that this analysis can give reasonably accurate results for highrise braced frames with multiple facade riggers. The method allows a simple procedure for obtaining the optimum level of the facade riggers in addition to a rapid assessment of the influence of the facade riggers on the performance of the highrise structure such as the reduction in lateral deflection at the top and the overturning moment at the base of the braced frame.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.789-799
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• 2019

The settlement hardly occurs in structures supported by pile foundation such as abutment, culvert but a cavity is formed in the lower part of a structure. As a result, soil discharged from the lateral ground to the cavity accelerates the settlement of the lateral ground of the structure, resulting in a larger settlement. Therefore, in order to prevent problems caused by cavity under the structure supported by pile foundation, soil Flow Protector (briefly called 'FLP'), which can be easily installed on the side of structure, was developed. In this study, an laboratory model test was carried out to prove the reduction effect of settlement and to estimate the optimal installation length of the FLP. As a result, the installation of the FLP reduced the settlement of the lateral ground and prevented the leakage of lateral ground soil into the cavity. If the stiffness of the FLP is small, the state or active earth pressure is generated in the upper part, which is not favorable for stability. But if the stiffness of the FLP is high enough, the passive earth pressure area is generated in the upper part, which will be advantageous for the stability. Also, the increased installation length of FLP is effective to reduce the settlement. And the ratio of the optimal length of the FLP to the box structure height (H = 250 mm) are flexible FLP 1.38, stiff FLP 0.73.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.3
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• pp.271-277
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• 2014

Internal structures, especially those located in the upstream of a reactor core, may have a significant influence on the core inlet flow rate distribution depending on both their shapes and the relative distance between the internal structures and the core inlet. In this study, to examine the effect of the reactor internal structure geometry treatment method on the prediction accuracy for the scale-down APR+ flow distribution, simulations with real geometry modeling were conducted using ANSYS CFX R.14, a commercial computational fluid dynamics software, and the predicted results were compared with those of the porous medium assumption. It was concluded that the core inlet flow distribution could be predicted more accurately by considering the real geometry of the internal structures located in the upstream of the core inlet. Therefore, if sufficient computational resources are available, an exact representation of these internal structures, for example, lower support structure bottom plate and ICI nozzle support plate, is needed for the accurate simulation of the reactor internal flow.

• Journal of the Korean Geotechnical Society
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• v.38 no.10
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• pp.61-74
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• 2022

Considering that the number of cases in which a structure foundation is located on weathered rock has been increasing recently, for adequate design bearing capacity of a foundation on weathered rock, allowable bearing capacities of such foundations in geotechnical investigation reports were studied. With reference to the study results, the allowable bearing capacity of a foundation on weathered rock was approximately 400-700 kN/m², with a large variation, and was considered a conservative value. Because the allowable bearing capacity of the foundation ground is an important index in determining the foundation type in the early design stage, it can have a significant influence on the construction cost and period according to the initial decision. Thus, in this study, six large-scale plate-bearing tests were conducted on weathered rock, and the bearing capacity and settlement characteristics were analyzed. According to the test results, the bearing capacities from the six tests exceeded 1,500 kN/m², and it shows that the results are similar with the one of bearing capacity formula by Pressuremeter tests when compared with the various bearing capacity formula. In addition, the elastic modulus determined by the inverse calculation of the load-settlement behavior from the large-scale plate-bearing tests was appropriate for applying the elastic modulus of the Pressuremeter tests. With consideration of the large-scale plate-bearing tests in this study and other results of plate-bearing tests on weathered rock in Korea, the allowable bearing capacity of weathered rock is evaluated to be over 1,000 kN/m². However, because the settlement of the foundation increases as the foundation size increases, the allowable bearing capacity should be restrained by the allowable settlement criteria of an upper structure. Therefore, in this study, the anticipated foundation settlements along the foundation size and the thickness of weathered rocks have been evaluated by numerical analysis, and the foundation size and ground conditions, with an allowable bearing capacity of over 1,000 kN/m², have been proposed as a table. These findings are considered useful in determining the foundation type in the early foundation design.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.9-20
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• 2002

The purpose of this research is to develop computational procedures for studying nonlinear soil-structure interaction Problems. In orders to study soil-structure interaction behavior, the finite element analysis for the strip footing subjected to both vortical and lateral loads, and foundation layer reinforced with sheet pile are considered, interface elements are used between the footing and the soil to model the interaction behavior The main analyzed results are as follows; 1. For the prediction of settlement and lateral displacement, the result due to interface element was evaluated larger then without interface element. 2. For the determination of ultimate bearing capacity, the value using interface element appeared smaller by 12%, which was safe. 3. The horizontal and vertical displacement of strip footing affected by the presence of interface element.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.59-67
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• 2002

The ultimate strength testing of a two-story, single-bay, and sway allowed space steel frame was performed. Considering a majority of large-scale frame tests in the past, only two-dimensional frames were experimentally studied. Therefore, three-dimensional experiment is needed to extend the knowledge of this field. The steel frame subjected to non-proportional vertical and horizontal load was tested. The load-displacement curve of the test frame is provided. The experiment results are useful for verification of the three-dimensional numerical analysis. The results obtained from 3D non-linear analysis using ABAQUS were compared with experimental data.