• Earthquakes and Structures
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• v.13 no.1
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• pp.39-50
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• 2017

Displacement response and corresponding maximum response energy of structures are key parameters to assess the dynamic effect or even more destructive structural damage of the structures. By employing them, this research has compared the structural responses of jacket supported offshore wind turbine (OWT) subjected to seismic excitations apprehending earthquake incidence, when (a) soil-structure interaction (SSI) has been ignored and (b) SSI has been considered. The effect of earthquakes under arbitrary angle of excitation on the OWT has been investigated by means of the energy based wavelet transformation method. Displacement based fragility analysis is then utilized to convey the probability of exceedance of the OWT at different soil site conditions. The results show that the uncertainty arises due to multi-component seismic excitations along with the diminution trend of shear wave velocity of soil and it tends to reduce the efficiency of the OWT to stand against the ground motions.

• Geomechanics and Engineering
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• v.6 no.2
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• pp.117-138
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• 2014

The main focus of the current study is to evaluate the dynamic behavior of a cantilever retaining wall considering backfill and soil/foundation interaction effects. For this purpose, a three-dimensional finite element model (FEM) with viscous boundary is developed to investigate the seismic response of the cantilever wall. To demonstrate the validity of the FEM, analytical examinations are carried out by using modal analysis technique. The model verification is accomplished by comparing its predictions to results from analytical method with satisfactory agreement. The method is then employed to further investigate parametrically the effects of not only backfill but also soil/foundation interactions. By means of changing the soil properties, some comparisons are made on lateral displacements and stress responses. It is concluded that the lateral displacements and stresses in the wall are remarkably affected by backfill and subsoil interactions, and the dynamic behavior of the cantilever retaining wall is highly sensitive to mechanical properties of the soil material.

• Magazine of korean Tunnelling and Underground Space Association
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• v.21 no.2
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• pp.117-129
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• 2019

Tunnelling in urban environments is very common nowadays as large cities are expanding and transportation demands require the use of the underground space for creating extra capacity. Inevitably, any such new construction may have significant effects on existing nearby infrastructure and therefore relevant assessment of structural integrity and soil-structure interaction is required. Foundation piles can be rather sensitive to nearby tunnel construction and therefore their response needs to be evaluated carefully. Although detailed three-dimensional continuum finite element analysis can provide a wealth of information about this behaviour of piles, such analyses are generally very computationally demanding and may require a number of material and other model parameters to be properly calibrated. Therefore, relevant simplified approaches are used to provide a practical way for such an assessment. This paper presents a simple method where the pile is modelled with beam finite elements, pile-soil interaction is modelled with soil springs and tunnelling-induced displacements are introduced as an input boundary condition at the end of the soil springs. The performance of this approach is assessed through some examples of applications.

• Ocean Systems Engineering
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• v.9 no.3
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• pp.241-259
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• 2019

This paper presents a fully three-dimensional numerical approach for analyzing deepwater drilling riser-conductor system vortex-induced vibrations (VIV) including nonlinear soil-structure interactions (SSI). The drilling riser-conductor system is modeled as a tensioned beam with linearly distributed tension and is solved by a fully implicit discretization scheme. The fluid field around the riser-conductor system is obtained by Finite-Analytic Navier-Stokes (FANS) code, which numerically solves the unsteady Navier-Stokes equations. The SSI is considered by modeling the lateral soil resistance force according to nonlinear p-y curves. Overset grid method is adopted to mesh the fluid domain. A partitioned fluid-structure interaction (FSI) method is achieved by communication between the fluid solver and riser motion solver. A riser-conductor system VIV simulation without SSI is firstly presented and served as a benchmark case for the subsequent simulations. Two SSI models based on a nonlinear p-y curve are then applied to the VIV simulations. Also, the effects of two key soil properties on the VIV simulations of riser-conductor systems are studied.

• Coupled systems mechanics
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• v.11 no.5
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• Smart Structures and Systems
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• v.15 no.5
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• pp.1293-1309
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• 2015

3D two adjacent buildings with different heights founded in different kinds of soil connected with viscous dampers groups, with especial arrangement in plane, were investigated. Soil structure interaction for three different kinds of soil (stiff, medium and soft) were modeled as 3D Winkler model to give the realistic behavior of adjacent buildings connected with viscous dampers under various earthquake excitations taking in the account the effect of different kinds of soil beneath the buildings, using SAP2000n to model the whole system. A range of soil properties and soil damping characteristics are chosen which gives broad picture of connected structures system behavior resulted from the influence soil-structure interaction. Its conclusion that the response of connected structures system founded on soft soil are more critical than those founded on stiff soil. The behavior of connected structures is different from those with fixed base bigger by nearly 20%, and the efficiency of viscous dampers connecting the two adjacent buildings is reduced by nearly 25% less than those founded on stiff soil.

• Interaction and multiscale mechanics
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• v.2 no.4
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• pp.397-411
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• 2009

The effect of soil-structure interaction on a simple single storeyed and two bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the three dimensional finite element analysis with realistic assumptions. The members of the superstructure and substructure are descretized using 20 node isoparametric continuum elements while the interface between the soil and pile is modeled using 16 node isoparametric interface elements. Owing to viability in terms of computational resources and memory requirement, the approach of uncoupled analysis is generally preferred to coupled analysis of the system. However, an interactive analysis of the system is presented in this paper where the building frame and pile foundation are considered as a single compatible unit. This study is focused on the interaction between the pile cap and underlying soil. In the parametric study conducted using the coupled analysis, the effect of pile spacing in a pile group and configuration of the pile group is evaluated on the response of superstructure. The responses of the superstructure considered include the displacement at top of the frame and moments in the superstructure columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation used in the study. The percentage variation in the values of displacement obtained using the coupled and uncoupled analysis is found in the range of 4-17 and that for the moment in the range of 3-10. A reasonable agreement is observed in the results obtained using either approach.

• Earthquakes and Structures
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• v.12 no.2
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• pp.251-262
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• 2017

The present research intends to study the effects of the seismic soil-foundation-structure interaction (SFSI) on the dynamic response of various buildings. Two methods including direct and Cone model were studied through 3D finite element method using ABAQUS software. Cone model as an approximate method to consider the SFSI phenomenon was developed and evaluated for both high and low rise buildings. Effect of soil nonlinearity, foundation rigidity and embedment as well as friction coefficient between soil-foundation interfaces during seismic excitation are investigated. Validity and performance of both approaches are evaluated as reference graphs for Cone model and infinite boundary condition, soil nonlinearity and amplification factor for direct method. A series of calculations by DeepSoil for inverse earthquake record modification was conducted. A comparison of the two methods was carried out by root-mean-square-deviation (RMSD) tool for maximum lateral displacement and story shear forces which verifies that Cone model results have good agreement with direct method. It was concluded that Cone method is a convenient, fast and rather accurate method as an approximate way to count for soil media.

• Earthquakes and Structures
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• v.16 no.1
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• pp.109-118
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• 2019

This study, analyses the seismic response for a rigid massless square foundation resting on a viscoelastic soil layer limited by rigid bedrock. The foundation is subjected either to externally applied forces or to obliquely incident seismic body or surface harmonic seismic waves P, SV and SH. A 3-D frequency domain BEM formulation in conjunction with the thin layer method (TLM) is adapted here for the solution of elastodynamic problems and used for obtained the seismic response. The mathematical approach is based on the method of integral equations in the frequency domain using the formalism of Green's functions (Kausel and Peck 1982) for layered soil, the impedance functions are calculated by the compatibility condition. In this study, The key step is the characterization of the soil-foundation interaction with the input motion matrix. For each frequency the impedance matrix connects the applied forces to the resulting displacement, and the input motion matrix connects the displacement vector of the foundation to amplitudes of the free field motion. This approach has been applied to analyze the effect of soil-structure interaction on the seismic response of the foundation resting on a viscoelastic soil layer limited by rigid bedrock.

• Earthquakes and Structures
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• v.12 no.2
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• pp.165-175
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• 2017

This paper studies soil properties uncertainty and its implementation in the seismic response evaluation of structures. For this, response sensitivity of two 4- and 12-story RC shear walls to the soil properties uncertainty by considering soil structure interaction (SSI) effects is investigated. Beam on Nonlinear Winkler Foundation (BNWF) model is used for shallow foundation modeling and the uncertainty of soil properties is expanded to the foundation stiffness and strength parameters variability. Monte Carlo (MC) simulation technique is employed for probabilistic evaluations. By investigating the probabilistic evaluation results it's observed that as the soil and foundation become stiffer, the soil uncertainty is found to be less important in influencing the response variability. On the other hand, the soil uncertainty becomes more important as the foundation-structure system is expected to experience nonlinear behavior to more sever degree. Since full This paper studies soil properties uncertainty and its implementation in the seismic response evaluation of structures. For this, response sensitivity of two 4- and 12-story RC shear walls to the soil properties uncertainty by considering soil structure interaction (SSI) effects is investigated. Beam on Nonlinear Winkler Foundation (BNWF) model is used for shallow foundation modeling and the uncertainty of soil properties is expanded to the foundation stiffness and strength parameters variability. Monte Carlo (MC) simulation technique is employed for probabilistic evaluations. By investigating the probabilistic evaluation results it's observed that as the soil and foundation become stiffer, the soil uncertainty is found to be less important in influencing the response variability. On the other hand, the soil uncertainty becomes more important as the foundation-structure system is expected to experience nonlinear behavior to more sever degree. Since full probabilistic analysis methods like MC commonly are very time consuming, the feasibility of simple approximate methods' application including First Order Second Moment (FOSM) method and ASCE41 proposed approach for the soil uncertainty considerations is investigated. By comparing the results of the approximate methods with the results obtained from MC, it's observed that the results of both FOSM and ASCE41 methods are in good agreement with the results of MC simulation technique and they show acceptable accuracy in predicting the response variability.