• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.5-11
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• 2015

Recently the necessity of developing the Load and Resistance Factor Design (LRFD) for shallow foundation has been raised to implement to the domestic design codes related to geotechnical engineering since the limit state design is requested as international technical standard for the foundation of structures. In this study, applicability of LRFD for shallow foundation on weathered soils was investigated and resistance factor for this case was proposed. The quantitative analyses on the uncertainty and resistance bias for shallow foundation on weathered soil ground were performed by collecting the statistical data about domestic case studies for design and construction of shallow foundation. Reliability analyses for shallow foundation were first performed using FDA (First-order Design value Approach) method. Resistance factors were calibrated using the load factors obtained from the specifications of shallow foundations on weathered soil ground. The influence of the load factors developed in this study on the resistance factors were discussed by comparing with the resistance factor obtained from using AASHTO load factors.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.5-14
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• 2004

The settlement of foundations under working load conditions is an important design consideration. Well-designed foundations induce stress-strain states in the soil that are neither in the linear elastic range nor in the range usually associated with perfect plasticity. Thus, in order to accurately predict working settlements, analyses that are more realistic than simple elastic analyses are required. The settlements of footings in sand are often estimated based on the results of in-situ tests, particularly the standard penetration test (SPT) and the cone penetration test (CPT). In this paper, we analyze the load-settlement response of vertically loaded footings placed in sands using both the finite element method with a non-linear stress-strain model and the conventional elastic approach. Based on these analyses, we propose a procedure for the estimation of footing settlement in sands based on CPT results.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.498-503
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• 2009

얕은기초의 침하량은 기초강성에 따라 크게 좌우되지만 기존의 이론적인 연구결과는 실무에 적 하기에 불충분하였다. 그러므로, 본 연구에서는 3차원 수치해석법을 이용하여 직사각형 기초의 길이비에 따른 강성 보정계수를 산정하고자 하였다. 우선, Mayne & Poulos(1999)가 정사각형 기초에 대하여 제안한 강성 보정계수와 비교하여 본 수치해석 기법의 적용성을 검증하였다. 그리고, 검증된 수치해석 기법을 적용하여 직사각형 기초의 길이비를 L/B=1, 2, 5로 달리하여 해석을 수행하였다. 그 결과, 동일한 기초강성에서 기초의 길이비(L/B)가 증가함에 따라 강성 보정계수 값이 점차 증가하는 결과를 보여주었다. 그러나 L/B=5 인 경우에는 강성계수가 10이상 되더라도 기초는 완전강성 거동을 보이지 않았다.

• Journal of the Korean Geotechnical Society
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• v.33 no.6
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• pp.5-16
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• 2017

Rocking behavior of shallow foundation during the earthquake can reduce the seismic load of the superstructure. The dynamic centrifuge tests were performed to investigate the availability of using rocking behavior for the weathered soil condition. The centrifuge test model was composed of the weathered soil, shallow foundation and single degree of freedom structure. And the accelerations of soil, foundation and structure, and the foundation settlement were measured during the earthquake. From the test result, the seismic load of the structure for the strong earthquake input was reduced by the rocking behavior with foundation uplift and the maximum foundation settlement was less than 0.5% of the foundation width. This shows the potential that the rocking foundation concept can be used in the economical seismic design of foundation for the weathered soil in the future with additional research and verification.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.13-20
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• 2010

This paper describes the procedure to predict the entire load-displacement curve and the failure mechanism of shallow strip footing for real soil. The presented results show that it is possible to analyze the post peak behavior of shallow strip footing and to give a progressive failure mechanism clearly. Finite element computation of the bearing capacity factor $N_{\gamma}$ have been made for shallow strip footings with friction angles and dilation angle. It is shown that commonly used values of $N_{\gamma}$ which have generally been based on associated plasticity calculations are unconservative for real soil with non-associated plasticity and some smooth footing.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.77-86
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• 2008

A database program is constructed by collecting all information related to shallow foundations such as measured load-settlement data, foundation shapes and sizes, properties of soils under the foundation and various measured data obtained from field investigation methods including CPT, PMT and SPT etc.. Based on the database program, a special program module is developed for performing statistical analyses of reliability and accuracy of predicting equations used for calculation of settlement of the shallow foundations. Special interests are focused not only on the settlement, but also on the settlement to width ratio (s/B). Results of the reliability and accuracy analyses on five available settlement equations are provided. Conclusions based on the provided results can be confirmed by extending number of related reliable data about the shallow foundations and can be adapted as guidelines for design of the shallow foundations.

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.55-62
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• 2005

The use of the bearing capacity equation is subjected to several uncertainties. In this study, estimation of the bearing capacity of footings based on the cone resistance q$_{c}$ is investigated. Non-linear finite element analyses based on a state-dependent stress-strain model were performed to obtain the load-settlement responses of axially loaded circular footings. Various soil and footing conditions, including different relative densities, depths of embedment, and footing diameters were considered in the analyses. Based on the finite element results, load-settlement curves were obtained and used to determine the unit limit bearing capacity in terms of the cone resistance q$_{c}$ for footings subjected to surcharge. Values of the unit bearing capacity for different embedment depths were in a narrow range, while considerable variation was observed with relative density D$_{R}$. It was observed that the unit limit bearing capacity normalized with respect to q$_{c}$ decreases as D$_{R}$ increases for a given surcharge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.923-932
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• 1994

The studies on the bearing capacity of shallow and deep foundations have been made in various fields and formulas for various failure mechanisms have been presented. But, for these models, the method of classification with foundation depth has been obscure and bearing capacity factors have not been uniformly applied. An experiment was performed, in plane strain conditions, with ground model made of carbon rods. The failure mechanism of foundation and ultimate bearing capacity with foundation depth were observed. Based on experimental results the classification between shallow and deep foundations by failure shape was tried. Various present failure mechanisms of foundation were verified through the experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6322-6328
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• 2014

Finite element analyses were performed to find out the load bearing behavior of three kinds of shallow foundations. The analysis results for strip footing showed that local shear failure mode could be observed for a zero dilatancy angle and general shear failure mode could be seen for non-zero dilatancy angles. The ultimate bearing loads for non-zero dilatancy angles were approximately 1.5 times higher than that of a zero dilatancy angle. General shear failure mode was observed for circular footing and square footing regardless of the dilatancy angle. The ultimate bearing loads for a non-zero dilatancy angle were slightly greater than that for a zero dilatancy angle. A comparison of the load-settlement curves for three kinds of footing showed that the load bearing capacities for non-zero dilatancy angle were greater than those for a zero-dilatancy angle.

• Geotechnical Engineering
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• v.36 no.5
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• pp.68-73
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• 2020