Parametric and nonparametric models of the impedance matrix of a random medium

International audienceTwo approaches are presented for the modeling of the impedance matrix of a random medium: one parametric and the other nonparametric. The former allows to take into account the data uncertainties while introducing a model error, that yields, in some cases, very high levels. The latter is based on a much simpler, deterministic, model, for which both data uncertainties and model errors are accounted for. When the model error is negligible, the parametric approach can be used for the identification of the parameters of the nonparametric model of the impedance matrix

A coupling method for stochastic continuum models at different scales

Workshop du projet ANR "Advanced methods using stochastic modeling in high dimension for uncertainty modeling, quantification and propagation in computational mechanics of solids and fluids", Institut Curie, Paris, December 6-7, 201

Construction of a probabilistic model for the soil impedance matrix using a non-parametric method

International audienceConstruction codes demand ever increasing earthquake-resisting features for strategic buildings such as dams and nuclear plants and the incorporation of uncertainty in the design models for these structures, particularly in soil domains, becomes a major issue. Parametric methods and a recent non-parametric method are considered for the construction of a probabilistic model of the soil impedance matrix, the latter supplying interesting features provided that the matrices of a certain mean model can be identified. This difficulty is tackled using a hidden state variables model, ensuring causality of the impedance and necessary positive definiteness conditions on the generated matrices. The identification of the uncertain parameters in the soil and the difficult task of quantifying their variability are not required and computational costs are significantly reduced

Numerical modelling of free field traffic-induced vibrations

This paper deals with the numerical modelling of free field traffic-induced vibrations during the passage of a vehicle on an uneven road. The road unevenness subjects the vehicle to vertical oscillations that cause dynamic axle loads. The latter are calculated from the vehicle transfer functions and the frequency content of the road profile as experienced by the vehicle ar;les. A transfer function between the source and the receiver that accounts for the dynamic interaction between the road and the soil is used to calculate the free field response. Its calculation is based on a dynamic substructure method, using a boundary element method for the soil and an analytical beam model for the road. The methodology is validated with analytical results and is finally illustrated by a numerical example where the free field vibrations during the passage of a vehicle on a traffic plateau are considered. (C) 2000 Elsevier Science Ltd. All rights reserved.status: publishe

Construction of a probabilistic model for the soil impedance matrix using a non-parametric method

International audienceConstruction codes demand ever increasing earthquake-resisting features for strategic buildings such as dams and nuclear plants and the incorporation of uncertainty in the design models for these structures, particularly in soil domains, becomes a major issue. Parametric methods and a recent non-parametric method are considered for the construction of a probabilistic model of the soil impedance matrix, the latter supplying interesting features provided that the matrices of a certain mean model can be identified. This difficulty is tackled using a hidden state variables model, ensuring causality of the impedance and necessary positive definiteness conditions on the generated matrices. The identification of the uncertain parameters in the soil and the difficult task of quantifying their variability are not required and computational costs are significantly reduced

Identification of some statistical parameters of a random heterogeneous medium using measurements of the surface wavefield

International audienceThis presentation discusses the identification of some statistical properties of an elastic random medium based on surface measurements. The influence of two fundamental factors in the diffusion regime, i.e. the ratio between the dominant wavelength and the correlation length of the heterogeneities, and the ratio between P and S wave speeds is studied. The influence of the correlation model is also assessed. The global diffusion time of the medium is then used as a key parameter to identify the correlation length of the random medium

Dynamics of structures coupled with elastic media-A review of numerical models and methods

This paper reviews issues and developments in the field of structure-environment interaction problems, in which the environment is an elastic body, possibly unbounded. It covers in particular the fields of soil-structure interaction, ground-borne noise and vibration emitted by transportation systems and wave diffraction by obstacles in an elastic medium. The general setting for a linear bounded structure coupled to an unbounded linear environment through a bounded interface is first recalled, and the domain decomposition technique classically used for its description is put up. Extensions for the cases of nonlinear structure and uncertain environment are then discussed. Finally, the ongoing research in the fields of unbounded interface, moving interface, and multiple interfaces are reviewed and summarized. © 2012 Elsevier Ltd.status: publishe

Identification de modèles probabilistes non paramétriques

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