• 산업기술연구
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• 제17권
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• pp.111-118
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• 1997

This thesis is an experimental research of investigating behavior of single pile, subjected to the vertical compression loads, using the centrifuge facility located in the geotechnical engineering laboratory in Kangwon National University. Centrifugal model experiments of model pile were carried out changing diameter of model pile, relative density of sandy ground and the gravitational level applied in the centrifuge. Thus, their effects on the load-settlement behavior and the ultimate bearing capacity of pile were investigated. Experimental results obtained from centrifuge model tests were compared with the theoretical or semi-empirical equations to analyze values of ultimate bearing capacity of model pile. When we compare the ultimate bearing capacity of experimental results with the ultimate bearing capacity of theorical results, the experimental results appear more higher in the De Beer method and Meyerhof. Expecially, Terzaghi method is very same as the experimental results normally.

• Geomechanics and Engineering
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• 제18권3호
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• pp.315-328
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• 2019

This paper presents an investigation on bearing capacity, load-settlement behavior and safety factor of rock-soil slopes reinforced using geogrid-box method (GBM). To this end, small-scale laboratory studies were carried out to study the load-settlement response of a circular footing resting on unreinforced and reinforced rock-soil slopes. Several parameters including unit weight of rock-soil materials (loose- and dense-packing modes), slope height, location of footing relative to the slope crest, and geogrid tensile strength were studied. A series of finite element analysis were conducted using ABAQUS software to predict the bearing capacity behavior of slopes. Limit equilibrium and finite element analysis were also performed using commercially available software SLIDE and ABAQUS, respectively to calculate the safety factor. It was found that stabilization of rock-soil slopes using GBM significantly improves the bearing capacity and settlement behavior of slopes. It was established that, the displacement contours in the dense-packing mode distribute in a broader and deeper area as compared with the loose-packing mode, which results in higher ultimate bearing load. Moreover, it was found that in the loose-packing mode an increase in the vertical pressure load is accompanied with an increase in the soil settlement, while in the dense-packing mode the load-settlement curves show a pronounced peak. Comparison of bearing capacity ratios for the dense- and loose-packing modes demonstrated that the maximum benefit of GBM is achieved for rock-soil slopes in loose-packing mode. It was also found that by increasing the slope height, both the initial stiffness and the bearing load decreases. The results indicated a significant increase in the ultimate bearing load as the distance of the footing to the slope crest increases. For all the cases, a good agreement between the laboratory and numerical results was observed.

• 터널과지하공간
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• 제8권2호
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• pp.146-156
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• 1998

Nemerical algorithms were developed to analyze the behavior of the double lining as well as ground mass separately or simultaneously. A lining interface element was especially developed, verified and applied to the study on the coupled interaction of shotcrete and the concrete lining. It could be known fro parameter studys on double lining support systems that as the contact surface between shotcrete and concrete lining was rougher, the more decreased bearing capacity against the cracking of the system. If the thickness of the shotcrete increased, the bearing capacity of the double lining also increased linearly with the thickness. If the thickness of the concrete lining increased, the bearing capacity of the double lining had the relationship of the characteristic S-shape of a sigmoid function with the thickness. When the thickness increased over a given value, it was not useful to increase more the thickness because bearing capacity had no remarkable change. It could be concluded that the behavior of the shotcrete and concrete lining was generally reversed before and after the ratio of horizontal to vertical earth preassure of 1.0 and 0.5 respectively. Therefore, we could guess that the movement which two shotcrete and concrete lining deflect toward each other around the crown caused a friction between two linings and thus this disadvantageous effect could contribute to reducing the bearing capacity against the cracking.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.133-138
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• 2008

본 연구에서는 대공간구조물의 기본적인 동적특성을 가지고 있으며 동시에 가장 간단한 구조이기도 한 아치에 납-고무면진 장치를 적용하여 지진거동을 분석하였다. 대공간구조물의 지진거동은 일반적인 골조구조물의 지진거동과 달리 수평지진에 의하여 수직방향으로 큰 지진응답이 나타나고 있다. 면진장치를 대공간 구조물에 적용할 경우에 수평지진하중에 의하여 수평방향 지진응답이 저감되는 것은 물론 면진장치의 수직강성으로 인하여 수직응답도 현저하게 저감되는 것을 알 수 있었다.

• Tribology and Lubricants
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• 제33권6호
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• pp.309-314
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• 2017

This paper presents a theoretical investigation of the dynamic characteristics of externally pressurized air pad bearings with closed loop grooves. These grooves are made on the surface of bearings to reduce the number of supply holes so that manufacturing costs can be reduced. The semi-implicit method is applied to calculate the time varying pressure profile on the air bearing surface owing to the advantages of numerical stability and fast time tracing characteristics. The static pressure of the groove bearings is much higher than that without grooves, so the groove bearings can provide high load carrying capacity. The equation of motion considering vertical motion and tilting motion are also solved using the Runge-Kutta 4th order method. By combining the semi-implicit method and the Runge-Kutta method, fast calculations of the dynamic behavior of the air bearing can be achieved. The variations of bearing reaction force, air film reaction moment, height, and tilting angle are investigated for the step force input, which is 20% higher than the bearing reaction, when the nominal clearance is 6 mm. The effect of the groove width and the groove depth are investigated by calculating the dynamic behavior. The possibility of the air hammering with the depth of the groove is found and discussed.

• 한국가스학회지
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• 제20권3호
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• pp.73-77
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• 2016

본 연구에서는 여러 가지의 절단면 형상을 구비한 중공축이 동등한 최적을 갖는 경우에 대한 변위거동 안전성을 유한요소법으로 해석하였다. FEM 해석결과에 의하면, 외측튜브, 중간튜브, 내측튜브와 이들 튜브 사이를 연결하기 위해 X-타입 또는 Y-타입의 칼럼을 설치하였을 때 중공축 길이의 중간부에서 발생하는 최대 변위량을 줄여주는 것으로 나타났다. 특히, 하중을 지지하기 위해 구비된 X-타입 또는 Y-타입의 칼럼을 위상차 없이 외측튜브와 내측튜브를 중심축을 향해 직접 연결하면 중공축의 변위량을 줄이는 효과가 있는 것으로 나타났다. 그리고 동등한 체적을 갖는 중공축에서 발생하는 수직 변위량을 줄여주고, 변위거동 안전성을 높이기 위해서는 하중을 지지하기 위한 칼럼의 두께를 두껍게 설계하는 것이 바람직함을 알 수 있다.

• 한국지반환경공학회 논문집
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• 제14권6호
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• pp.5-11
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• 2013

국내의 소음 진동규제는 점점 더 강화되고 있어 도심지 근접시공을 위해 현재의 저소음 저진동 공법보다 더욱 환경친화적인 공법이 필요하게 되었다. 이 연구에서는 무소음 무진동 공법을 위한 스크류콘크리트말뚝공법의 특징에 대하여 설명하였으며 국내 특정 현장에서 시험시공을 실시하고 말뚝재하시험을 실시하여 시공방법에 따른 연직하중 지지능력을 연구하였다. 선행굴착방식으로 시공된 스크류콘크리트말뚝의 연직압축지지력이 선단분출형슈방식으로 시공된 스크류콘크리트말뚝의 그것보다 70% 이상 크게 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.95-98
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• 1992

In large panel structures, the design of joints which interconnect panels, is important deciding the load-bearing capacity of structures. Being various factors in the design of joints, it is difficult to develop a the critical system for the structural analysis of large concrete panel structures. Therefore there is a tendency to depend on the experiment. The purpose of this paper is to investigate the strength and the mechanical behavior of vertical joints in large concrete panel structures.

• Earthquakes and Structures
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• 제26권6호
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• pp.449-461
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• 2024

The vertical reinforcement connection between the precast reinforced concrete shear wall and the cast-in-place reinforced concrete member is vital to the performance of shear walls under seismic loading. This paper investigated the structural behavior of three precast reinforced concrete shear walls, with different levels of connection (i.e., full connection, partial connection, and no connection), subjected to quasi-static lateral loading. The specimens were subjected to a constant vertical load, resulting in an axial load ratio of 0.4. The crack pattern, failure modes, load-displacement relationships, ductility, and energy dissipation characteristics are presented and discussed. The resultant seismic performances of the three tested specimens were compared in terms of skeleton curve, load-bearing capacity, stiffness, ductility, energy dissipation capacity, and viscous damping. The seismic performance of the partially connected shear wall was found to be comparable to that of the fully connected shear wall, exhibiting 1.7% and 3.5% higher yield and peak load capacities, 9.2% higher deformability, and similar variation in stiffness, energy dissipation capacity and viscous damping at increasing load levels. In comparison, the seismic performance of the non-connected shear wall was inferior, exhibiting 12.8% and 16.4% lower loads at the yield and peak load stages, 3.6% lower deformability, and significantly lower energy dissipation capacity at lower displacement and lower viscous damping.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.355-362
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• 2001

Since micropiles were conceived in Italy in the early 1950s, which have been widely used for In-situ reinforcement, bearing pile or the concept of combination in the world-wide. The meaning of micropiles usually differs from that of a general deep foundation. Because the load capacity of it was mainly affected by skin friction. Also, it could be obtained the improvement effects of load capacity or ground's rigidity by the unitary behavior of ground and micropiles. In this study, The model tests were peformed on the dense sand where micropiles are set to the vertical direction. Strip footing was used in it. Steel bars of dia. 2 and 4㎜ were used in model tests of which the sand was attached on the surface, and the length of it was changed as 2B to 6B(where, B is width of strip footing) Through this process, the load capacity were analyzed from the test results in the relationship between load and displacement.