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This work deals with the coupling of the Finite Element Method (FEM) and the Boundary Element Method (BEM) to model interacting saturated porous and sealed elastic media. In this coupled analysis, the porodynamic subdomains of the model are discretised by the FEM, and the elastodynamic interacting subdomains are discretised by the BEM. Nonlinearities may be considered within the FEM subdomains. An iterative coupling approach is adopted, which leads to an efficient and easy to implement formulation, enabling the FEM and BEM modules to be handled separately. The iterative coupling methodology allows nonlinear analyses to be carried out quite directly, considering a single iterative loop for all iterative computations. It also permits independent discretisations to be straightforwardly applied for each subdomain of the model, taking into account simple interpolation/extrapolation procedures on common interfaces. Optimal relaxation parameters are considered to speed up the convergence of the iterative coupling analysis. At the end of the manuscript, numerical examples are presented, illustrating the performance of the proposed formulation. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a numerical model of the vertical time-harmonic response of a piled-raft foundation under external and seismic excitations. The surface raft is a circular, rigid plate on the surface of the soil, while the pile is represented by a classical finite element bar model embedded within the soil. The soil is modeled as a homogeneous, transversely isotropic, viscoelastic half-space. The fully coupled response of the plate–pile–half-space system is modeled through a superposition of Green's functions, in the framework of the indirect boundary element method. The article investigates the response of the coupled system for different sets of constitutive parameters, especially with regards to the effectiveness of the pile in reducing vibration amplitudes of the surface plate. [ABSTRACT FROM AUTHOR]

The study of solid–solid interaction problems is of significant interest in many engineering areas, such as structural dynamics or soil–structure interaction problems. In many of these cases, a localized and well-defined structure is embedded or connected to an infinite or semi-infinite domain, and thus the best option is to use different numerical techniques to model each part of the problem. In this paper, the authors propose two iterative coupling strategies to tackle this type of problem, considering the structure to be modelled by the FEM and the soil by the BEM. In both approaches, optimized relaxation parameters are employed, improving the efficiency of the analyses. Within the proposed iterative coupling algorithms, adaptive refinement of the FEM mesh may also be performed, in order to increase the accuracy of the calculations. Numerical examples are presented in the end of the manuscript, illustrating the main features of the proposed methods, assessing their applicability and effectiveness. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to describe the development of a 3D BEM–FEM code for ground–structure interaction. The technical choices and difficulties are reported. In particular, the multitraction problem has been implemented in 3D following a technique recently published in 2D for elastodynamics. It is showed that the separation of tractions is mandatory at corners but not at edges. The free surface and infinite interlayers are meshed by means of finite planes of varying dimensions. The paper also focuses on the validity of 2.5 approaches suggesting that in many situations the 2.5D model is well adapted. Reference situations are used for validation. The case of a pile joining a free surface and an interlayer between two different soils is described in detail. Finally computations are validated against measurements. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method based on a three dimensional boundary element-finite element coupled formulation in the time domain. The proposed model allows studying soil–structure interaction problems. The soil is modelled with the boundary element method, where the radiation condition is implicitly satisfied in the fundamental solution. Layered half-space Green׳s function including internal material damping is considered as the fundamental solution because of the influence of soil stratification on soil–structure interaction problems is large. This fundamental solution is computed from the exact expressions for the response in the underlying half-space and from a modal solution for the layers. The finite element method is used to represent the structure. In this paper the proposed method is validated by comparison with analytical and numerical results, and an experimental study is done. Afterwards, the dynamic behaviour of a building subjected to an incident wave field is studied. [ABSTRACT FROM AUTHOR]

This paper discusses the coupling of finite element (FE) and boundary element (BE) methods for the solution of transient dynamic soil–structure interaction problems in the time domain. As both the FE and the BE method impose different requirements on the time step for reasons of stability and accuracy, iterative coupling schemes are applied since they allow for a different time discretization in both subdomains. Apart from a direct coupling approach, various sequential and parallel iterative coupling strategies are investigated, imposing either Neumann or Dirichlet boundary conditions on the FE and BE subdomains. The use of interface relaxation accelerates convergence, where Aitken׳s Δ 2 - method provides an optimal relaxation parameter for all iterative strategies considered. It is demonstrated that the boundary conditions applied to each subdomain strongly affect the efficiency of these algorithms; the application of Neumann boundary conditions on the stiffest subdomain results in the fastest convergence. The iterative coupling strategy is useful in the case where different time steps are used in both subdomains, though a direct coupling can also be used. The iterative coupling strategy is finally applied to the computation of ground vibrations from impact pile driving. [ABSTRACT FROM AUTHOR]