Pérsio Leister de Almeida Barros

Elastodynamic Greens functions for orthotropic planestrain continua with inclined axes of symmetry

The article reports a methodology to synthesize the response of plane strain orthotropic and transversely isotropic half-spaces and full-spaces with arbitrarily oriented symmetry axes and subjected to concentrated and to distributed loads. Numerical results include the response of a half-space and a full-space to a uniform strip load. The examples presented analyze the influence of coordinate axis rotation and of the continuum anisotropy ratios. Stationary dynamic behavior is assumed throughout the article.

On the Dynamic Interaction and Cross-Interaction of 2D Rigid Structures with Orthotropic Elastic Media Possessing General Principal Axes Orientation

A direct boundary element method (BEM) implementation for the dynamic interaction analysis in the frequency domain of 2D rigid structures with elastic orthotropic media is presented. The BEM implementation is based on non-singular full-space influence functions. The rigid structure response is obtained by applying equilibrium and kinetic compatibility conditions. The method is applied to the analysis of the dynamic response of a rigid tunnel in a half-space with various elasticity principal axes inclinations and to the analysis of two rigid rectangular galleries in a half space with various distances between them.

Singular-ended spline interpolation for two-dimensional boundary element analysis

A method of interpolation of the boundary variables that uses spline functions associated with singular elements is presented. This method can be used in boundary element method analysis of 2-D problems that have points where the boundary variables present singular behaviour. Singular-ended splines based on cubic splines and Overhauser splines are developed. The former provides C2-continuity and the latter C1-continuity across element edges. The potentialities of the methodology are demonstrated analysing the dynamic response of a 2-D rigid footing interacting with a half-space. It is shown that, for a given number of elements at the soil–foundation interface, the singular-ended spline interpolation increases substantially the displacement convergence rate and delivers smoother traction distributions. Copyright

SCR-Seafloor Interaction Modeling With Winkler, Pasternak and Kerr Beam-on-Elastic-Foundation Theories

This paper discusses the use of three analytical models for the SCR-soil interaction analysis. Analytical derivations for Winkler, Pasternak and Kerr models are presented. The effects of the adopted model on displacements and stresses near the riser touchdown point are addressed. Comparisons with the results from a continuous soil model calculated with finite elements are also presented. In the regions with large displacement gradients, the Kerr model, which considers the influence of the elasticity from neighboring area, presents the best agreement with the 3D Finite Element model.© 2009 ASME

Oedometer Consolidation Test Analysis by Nonlinear Regression

A numerical method based on least squares nonlinear regression for the evaluation of the consolidation parameters of soils from consolidation tests is presented. A model which includes the initial compression, the primary consolidation, and the secondary compression is used in the regression. This approach allows the resulting regression curve to better fit the experimental data. The method takes the settlement-time readings from the oedometer step-loading consolidation test and calculates automatically the magnitudes of the coefficients of consolidation and of secondary compression. The performance of the proposed method is accessed through consolidation tests executed on four different clay soils, which are analyzed by nonlinear regression and by the usual graphical methods. It is concluded that the proposed method gives results that are close to those obtained by the standard methods of analysis.