• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.106-113
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• 2002

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used for a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted for soil. These two fields are coupled using FE-BE coupling technique In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, the dynamic response analyses of interface spring elements are performed. As a result, less spring stiffness makes the natural frequency decrease and the resonant amplitude increase.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.443-450
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• 2000

In this study a numerical method for soil-pile interaction analysis buried in multi-layered half planes is presented in frequency domain using FE-BE coupling. The total soil-pile interaction system is divided into two parts so called far field and near field beam elements are used for modeling a pile and coupled with plain strain elements for soil modeling. Boundary element formulation using the multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered dynamic fundamental solution is adopted to the far field and coupled with near field modeled by finite elements. In order to verify the proposed soil-pile interaction analysis method the dynamic responses of a pile on multi-layered half-planes are performed and compared with experiment results. Through this developed method the dynamic response analysis of a pile buried in multi-layered half planes can be calculated effectively in frequency domain.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.117-124
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• 2002

The major purpose of this study is to determine the dynamic behavior of soil-pile-structure interaction system considering the underground cavity. For the analysis, a numerical method fur ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. For the verification of dynamic analysis in the frequency domain, both forced vibration analysis and free-field response analysis are performed. The behavior of soil non-linearity is considered using the equivalent linear approximation method. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis considering the underground cavity in 2D problem.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.33-40
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• 2008

The load distribution and deformation of rock-socketed drilled shafts subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance in rock-socketed drilled shafts using the 2D elasto-plastic finite element analysis. Slippage and shear load transfer behavior at the pile-soil interface are investigated by using a user-subroutine interface model (FRlC). It is shown that the coupled soil resistance provides the influence of pile toe settlement as the shaft resistance is increased to an ultimate limit state. The results show that the coupling effect is closely related to the value of pile diameter over rock mass modulus (D/$E_{mass}$) and the ratio of total shaft resistance against total applied load ($R_s$/Q). Through comparisons with field case studies, the 2D numerical analysis reseanably presented load transfer of pile and coupling effect due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.437-448
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• 2000

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used lot a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted lot soil. These two fields are coupled using FE-BE coupling technique. In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, various numerical analyses of piles considering different conditions of soil-pile interaction system are performed to examine the dynamic behavior of the system. It has been found that the developed method which satisfies the radiation conditions of multi-layered half planes can be applied to various structure systems effectively in frequency domain.

• Journal of the Korean Geotechnical Society
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• v.23 no.9
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• pp.39-49
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• 2007

The load deformation behavior of the cap-pile-soil system is investigated, based on numerical analysis. Special attention is given to consideration of pile cap flexibility. Rigid pile cap analysis and flexible cap analysis were conducted for comparison. A numerical method that takes into account the coupling between the rigidities of the piles, the cap, and the column has been introduced to analyze the response of pile group supported columns. The prediction of the lateral loads and bending moments in the pile cap is much more conservative for a flexible cap than for a rigid cap.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.480-490
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• 2016

As wind turbines become larger and lighter, they are likely to respond sensitively by dynamic loads applied on them. Since the responses at resonances are particularly interested, it is required to be able to predict natural frequencies of wind turbines reliably at early design stage. To achieve this, the foundation-soil analysis is needed to be carried out and a finite element approach is adopted in general. However, the finite element approach would not be appropriate in early design stage because it demands heavy efforts in pile-soil modelling and computing facilities. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to handle. Therefore, they would be a useful tool in predicting a pile-soil interaction, particularly in early design stage. In this study an analysis for a pile inserted in soil is performed. The pile and soil are modelled as a beam and continuum medium, respectively, within an elastic range. In this analysis, influence factors at the pile head for lateral loads are predicted by means of this continuum approach for various length-diameter ratios of the pile. The influence factors predicted are validated with those reported in literature, proposed from a finite element analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.359-366
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• 2008

The load distribution and deformation of pile subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance that is closely related to the ratio of pile diameter to soil modulus $(D/E_s)$ and the ratio of total shaft resistance against total applied load $(R_s/Q)$, in rock-socketed drilled shafts using the coupled load-transfer method. The proposed analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Through comparisons with field case studies, it was found that the proposed method in the present study estimated reasonable load transfer behavior of pile and coupling effects due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.295-308
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• 2004

In this study, several Soil-Structure-Interaction (SSI) analyses were performed using the developed FE-BE coupling method and the seismic response behavior of the structure's systems was determined. For the verification of the fundamental solution which is used in this analysis method, a dynamic analysis of the homogeneous ground was performed and it was compared to the results of Estorff et al. In order to verify the seismic response analysis, the results are compared with those of another commercial code. Several kindd of SSI analyses were performed and the seismic response associated with the rile foundation, seismic waves and a consideration of the ground nonlinearity were determined. As a result, it was found that the pile foundations didn't greatly helpful during the seismic event.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.61-70
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• 2008

Load settlement behaviors and load transfer characteristics of rock-socketed pile subjected bi-directional load at pile tip were investigated using bi-directional pile load tests (BD PLT) performed on ten large-diameter drilled shafts at four sites. Based on test results, additional pile-toe displacement ($w_{bs}$) by coupled soil resistance was analyzed, and thus equivalent top loaded load-settlement curve of pile subjected bi-directional load was proposed by taking into account the coupled soil resistance. Through comparisons with field case studies, it is found that for test piles there exists effect of coupled soil resistance, which is represented by wbs, and thus an equivalent curve obtained by existing uncoupled methods can overestimate bearing capacity of piles by BD PLT. On the other hand, the analysis by the proposed method with soil coupling effect has a considerably larger settlement when compared with the results by uncoupled load transfer method and estimates reasonable load-settlement behaviors of test piles. In case of pile socketed in high strength rocks, however, effects of coupled soil resistance can be neglected.