• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.782-791
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• 2009

This study was carried out the laboratory tests and field plate load test in order to evaluate the reinforcement effect of geocell for road construction. The geocell-reinforced subgrade shows the increment of cohesion and friction angle with comprison of non-reinforced subgrade. In addition, the field plate load test was performed on the geocell-reinforced subgrade to estimate the bearing capacity of soil. The direct shear test was conducted with utilizing a large-scale shear box to evaluate the internal soil friction angle with geocell reinforcement. The number of cells in the geocell system is varied to investigate the effect of soil reinforcement. The theoretical bearing capacity of subgrade soil with and without geocell reinforcement was estimated by using the soil internal friction angle. The field plate load tests were also conducted to estimate the bearing capacity with geocell reinforcement. It is found out that the bearing capacity of geocell-reinforced subgrade gives 2 times higher value than that of unreinforced subgrade soil. In the future, the reinforcement effect of the geocell rigidity and load-balancing effect of the geocells should be evaluated.

• Steel and Composite Structures
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• 제28권5호
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• pp.641-653
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• 2018

This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

• 산업기술연구
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• 제27권A호
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• pp.121-130
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• 2007

Centrifuge model tests were performed to find appropriate equations proposed previously of estimating the bearing capacity of the composite clayey soil reinforced with sand compaction pile. Model tests were carried out with changing the replacement ratio of SCP (20%, 40%, 70%), contents of fine materials (5%, 10%, 15%) and ratio of treated width to loading width (1B, 2B, 3B). Test results about bearing capacity of the composite ground were obtained by performing the surcharge load tests with measurements of applied loads and vertical displacement. Bearing capacities against bulging and shear failures were estimated by the existing equations. As results of comparing the estimated bearing capacity with experimental values the bearing capacities estimated by Greenwood's equation (1970) for bulging failure mode were similar to the test results.

• Steel and Composite Structures
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• 제23권4호
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• pp.409-420
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• 2017

This paper theoretically studies the cyclic behavior of hybrid connections between steel coupling beams and concrete shear walls with embedded steel columns. Finite element models of connections with long and short embedded steel columns are built in ABAQUS and validated against the test results in the companion paper. Parametric studies are carried out using the validated FE model to determine the key influencing factors on the load-bearing capacity of connections. A close-form solution of the load-bearing capacity of connections is proposed by considering the contributions from the compressive strength of concrete at the interface between the embedded beam and concrete, shear yielding of column web in the tensile region, and shear capacity of column web and concrete in joint zone. The results show that the bond slip between embedded steel members and concrete should be considered which can be simulated by defining contact boundary conditions. It is found that the loadbearing capacity of connections strongly depends on the section height, flange width and web thickness of the embedded column. The accuracy of the proposed calculation method is validated against test results and also verified against FE results (with differences within 10%). It is recommended that embedded steel columns should be placed along the entire height of shear walls to facilitate construction and enhance the ductility. The thickness and section height of embedded columns should be increased to enhance the load-bearing capacity of connections. The stirrups in the joint zone should be strengthened and embedded columns with very small section height should be avoided.

• 한국지반환경공학회 논문집
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• 제5권1호
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• pp.55-64
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• 2004

본 연구에서는 쇄석다짐말뚝의 합리적인 국내 적용을 위하여 쇄석다짐말뚝의 지지력에 가장 크게 영향을 미치는 주요 설계 파라미터에 대한 민감도 분석을 실시하고 단일 쇄석다짐말뚝의 주요 파괴 메커니즘인 Bulging과 General Shear Failure시에 대해 주요 파라미터가 지지력 예측에 미치는 영향을 분석하여, 향후 쇄석다짐말뚝의 설계를 위한 지반조사 및 시험시에 활용할 수 있도록 하였다. 또한 국내 현장에서 시행한 재하시험 결과를 이용하여 현재 주로 이용되고 있는 지지력 예측 이론들의 적용성을 평가하였다. 분석결과, Bulging 및 General Shear Failure시의 기존의 지지력 이론식으로 구한 극한지지력이 정재하시험의 실측치보다 과소평가하였으며, 원지반의 비배수전단강도, 쇄석다짐말뚝의 내부마찰각, 횡방향응력, 원지반이 받는 상재하중 등이 극한지지력에 큰 영향을 미치는 것으로 나타났다. 특히, General Shear Failure시의 민감도 분석결과, 원지반의 비배수 전단강도, 쇄석다짐말뚝의 내부마찰각, 원지반이 받는 상재하중의 변화에 따른 지지력은 각 제안식 별로 크게 차이가 나타났다.

• 한국터널지하공간학회 논문집
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• 제13권3호
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• pp.277-289
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• 2011

본 연구에서는 압축력을 받는 터널 라이닝 부재 특성에 보다 부합된 조건에서 FRP-콘크리트 접촉면의 전단 저항력을 평가할 수 있는 새로운 시험법을 제안하였으며, 제안 시험법은 기존 시험방법에 비해 시험체 제작과 시험방법이 매우 용이하다. 제안된 시험법을 기반으로 FRP와 콘크리트 복합소재의 전단저항성능을 좌우하는 규사코팅의 최적조건을 도출하기 위한 매개변수 연구를 실시하였다. 다양한 시료에 대한 시험결과를 기존 연구결과와의 비교분석을 통하여 제안 시험법의 타당성을 보였으며, FRP부재와 콘크리트 접촉면의 전단저항을 극대화 시킬 수 있는 효과적인 규사입경 및 밀도에 대한 최적 조건을 제시하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.558-561
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• 2001

SIP(Soil cement Injected Precast pile) that inserts a precast pile after injecting a cement paste into a boring has been applied rapidly through the change of construction circumstances. But there isnt any logical equation of a bearing capacity fitted to SIP yet. So Meyerhof equation has mainly been used to predict a bearing capacity in a design stage instead. But it has shortcomings such as lack of confidence because it has derived not from a theory but from an experience obtained from the result of SPT (Standard Penetration Test) and because a penetration depth tends to be deeper by an excessive design that depends on an end bearing capacity of a pile more than a skin frictional resistance. In this study, thereupon, a direct shear test in the laboratory was performed to both SM and SC soils in variable conditions to verify skin friction properties for the purpose of presenting some reasons capable of reducing penetration depths. Through the tests, soil to soil of SM in cohesion, rough panel to soil of SM in friction angle and soil to soil of SM in shear strength tended to be high. And a shear strength increased as its total unit weight increased in all cases.

• Geomechanics and Engineering
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• 제38권1호
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• pp.93-106
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• 2024

The present paper investigates the spatial variability effect of soil property on the three-dimensional probabilistic characteristics of the bearing capacity factor (i.e., mean and coefficient of variation) of a circular footing resting on clayey soil where both mean and standard deviation of undrained shear strength increases with depth, keeping the coefficient of variation constant. The mean trend of undrained shear strength is defined by introducing the dimensionless strength gradient parameter. The finite difference method along with the random field and Monte Carlo simulation technique, is used to execute the numerical analyses. The lognormal distribution is chosen to generate random fields of the undrained shear strength. In the study, the potential failure of the structure is represented through the failure probability. The influences of different vertical scales of fluctuation, dimensionless strength gradient parameters, and coefficient of variation of undrained shear strength on the probabilistic characteristics of the bearing capacity factor and failure probability of the footing, along with the probability and cumulative density functions, are explored in this study. The variations of failure probability for different factors of safety corresponding to different parameters are also illustrated. The results are presented in non-dimensional form as they might be helpful to the practicing engineers dealing with this type of problem.

• Steel and Composite Structures
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• 제26권2호
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• pp.183-196
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• 2018

The traditional prestressed concrete composite box-girders with corrugated steel webs have several drawbacks such as large deflection and potential local buckling. In this study, two methods were investigated to optimize and improve the prestressed concrete composite box-girders with corrugated steel webs. The first method was to replace the concrete bottom slab with a steel plate and the second method was to support the concrete bottom slab on the steel flanges. The behavior of the prestressed concrete composite box-girders with corrugated steel webs with either method was studied by experiments on three specimens. The test results showed that behavior of the optimized and upgraded prestressed concrete composite box-girders with corrugated steel webs, including ultimate bearing capacity, flexural stiffness, and crack resistance, is greatly improved. In addition, the influence of different shear connectors, including perfobond leisten (PBL) and stud shear connectors, on the behavior of prestressed concrete composite box-girders with corrugated steel webs was studied. The results showed that PBL shear connectors can greatly improve the ultimate bearing capacity, flexural stiffness and crack resistance property of the prestressed concrete composite box-girders with corrugated steel webs. However, for the efficiency of prestressing introduced into the girder, the PBL shear connectors do not perform as well as the stud shear connectors.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.842-847
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• 2008

Despite of the increasing number of the application of the drilled shaft pile in construction site, most of the study of pile capacity has been centered side shear resistance. But it is common that the drilled shaft is socketed on the rock so as to use the bearing resistance, so prediction of the toe's movement and characteristic of the bearing capacity is important as the side shear resistance. Therefore the model tests were performed in order to study the characteristic of bearing capacity on rock mass. The material of the test blocks were the mortar which was mixed with sand, cement and water, and test block size was $240{\times}240{\times}240mm$. Load was pressed by the 45mm of diameter of miniaturized pile and plate jack and steal plate were used to the confined stress for representing the underground condition. The relation of load-displacement was measured in many different conditions of rock mass such as direction of discontinuities, spacing and strength, and q-w curves of the toe of the pile were verified in each condition.