WorldCat Identities

Bertrand, David (1978-....).

Overview
Works: 4 works in 8 publications in 2 languages and 9 library holdings
Roles: Thesis advisor, Opponent, Author
Publication Timeline
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Most widely held works by David Bertrand
Modélisation du comportement mécanique d'une structure cellulaire soumise à une sollicitation dynamique localisée : application aux structures de protection contre les éboulements rocheux by David Bertrand( Book )

3 editions published in 2006 in French and held by 3 WorldCat member libraries worldwide

This thesis is dedicated to the modelling and to the mechanical analysis of a rockfall protection barrier under dynamic impact. The considered rockfall dam is built with an assembly of parallelepiped cells. Cells are wire netting cages filled with granular material. A multi-scale approach is proposed to study the behaviour of the structure. In order to model the rockfall protection dam and its components, the distinct element method is used. The double twisted hexagonal mesh of the cells is described by a discretization of the wire netting sheet. The elasto-plastic behaviour of the wire mesh is considered until the failure. After the coupling of the wire mesh with the granular material under the same computing environment, the mechanical behaviour of a single cell is explored under different loading paths in quasi-static and dynamic conditions. Form these tests, a constitutive model representative of the macroscopic behaviour of the cell is proposed in order to model the structure. Discrete elements are used to model the structure. The interactions between these elements are described by the constitutive model of the cell. The study of the structure behaviour submitted to a dynamic loading is carried out to show the influence of structural parameters and the influence of impact conditions
Contribution à la modélisation par éléments finis des structures en béton armé soumises à des avalanches de neige : Application à la structure de protection de Taconnaz by Isabelle Ousset( )

2 editions published between 2015 and 2020 in French and held by 2 WorldCat member libraries worldwide

Snow avalanches threaten people and also different types of civil engineering structures in mountainous areas. This PhD thesis focuses on a protective RC (Reinforced Concrete) structure consisting of an L-shaped wall. The objective of this study is to calibrate and validate a 2D FE (Finite Element) model in order to explore the mechanical behavior of such RC structures loaded by snow avalanche pressure fields and to assess their vulnerability when exposed to this kind of natural hazard. Four constitutive laws describing the concrete rheology were tested to describe the collapse of the RC wall. A physical 1/6-scale model permitted obtaining, via a pushover test, useful experimental data for the calibration of the proposed FE models. Two concrete models allowed converging to a relevant collapse of the structure in agreement with the experimental observations. Then, the calibrated FE model was used to investigate the mechanical response of the wall under avalanche loading. According to the impulse of the loading signal, three regimes can occur (quasi-static, dynamic or impulsive). In the case of dense-snow avalanches, the results show that the mechanical response of this structure can be described as quasi-static. However, avalanche signals depend on many factors (type of avalanche, density, temperature, etc.) and several types of responses can potentially develop. Finally, the vulnerability and the reliability of the RC wall were studied to show the influence of the geometry and the material properties on the capacity of the protective structure. In fine, these results will be used in an integrated risk framework in order to help decision makers
Reliability of reinforced concrete structures : Case of slabs subjected to impact by Fidaa Kassem( )

2 editions published between 2015 and 2020 in English and held by 2 WorldCat member libraries worldwide

Reinforced concrete structures (RC) are subjected to several sources of uncertainties that highly affect their response. These uncertainties are related to the structure geometry, material properties and the loads applied. The lack of knowledge on the potential load, as well as the uncertainties related to the features of the structure shows that the design of RC structures could be made in a reliability framework. This latter allows propagating uncertainties in the deterministic analysis. However, in order to compute failure probability according to one or several failure criteria, mechanical and stochastic models have to be coupled which can be very time consuming and in some cases impossible. The platform OpenTURNS is used to perform the reliability analysis of three different structures . OpenTURNS is coupled to CASTEM to study the reliability of a RC multifiber cantilever beam subjected to a concentrated load at the free end, to Abaqus to study the reliability of RC slabs which are subjected to accidental dropped object impact during handling operations within nuclear plant buildings, and to ASTER to study the reliability of a prestressed concrete containment building. Only the physical problem of reinforced concrete impacted by a free flying object is investigated in detail. Two deterministic models are used and evaluated: a 3D finite element model simulated with the commercial code “Abaqus/Explicit” and an analytical mass-spring model. The aim of this study is to address this issue of reliability computational effort. Two strategies are proposed for the application of impacted RC slabs. The first one consists in using deterministic analytical models which predict accurately the response of the slab. In the opposite case, when finite element models are needed, the second strategy consists in reducing the number of simulations needed to assess the failure probability. In order to examine the reliability of RC slabs, Monte Carlo and importance sampling methods are coupled with the mass-spring model, while FORM is used with the finite element model. These two stategies are compared in order to verify their efficiency to calculate the probability of failure. Finally, a parametric study is performed to identify the influence of deterministic model parameters on the calculation of failure probability (dimensions of slabs, impact velocity and mass, boundary conditions, impact point, reinforcement
Évaluation du niveau de dégradation du bois dans les ouvrages de protection par spectroscopie proche infrarouge et analyse vibratoire by Jean-Baptiste Barré( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

La construction d'ouvrages de protection répond à la nécessité de se protéger d'aléas naturels comme les phénomènes d'érosion ou de glissement de terrain. Si le béton est classiquement utilisé pour la construction de tels ouvrages, le bois est régulièrement employé sur des aléas engendrant des contraintes faibles ou modérées. Pour cela, les praticiens s'appuient sur deux approches différentes, le génie civil et l'ingénierie écologique, qui requièrent, dans ce contexte, la mise en œuvre d'une structure construite sur la base d'un agencement de rondins de bois d'essence locale. Il existe cependant des lacunes de connaissances freinant la prescription de ces ouvrages. Les verrous scientifiques concernent notamment l'évaluation du niveau de dégradation, au sens des propriétés mécaniques, des rondins pour le suivi des ouvrages existants.L'objectif de cette thèse est de développer deux méthodes d'évaluation du niveau de dégradation de rondins de sapin blanc à partir de la spectroscopie proche infrarouge (SPIR) et de l'analyse vibratoire. Dans ce travail de thèse, le niveau de dégradation d'un rondin est défini à partir du taux de perte en module d'élasticité ou en module de rupture par rapport à leur valeur à l'état intact.Les résultats obtenus ont montré que les méthodes développées permettaient d'évaluer le niveau de dégradation de rondins aussi bien en conditions semi-contrôlées qu'en conditions naturelles. La méthode par SPIR évalue le niveau de dégradation à partir de modèles de prédiction des indicateurs de référence Dw_{MOE} et Dw_{MOR} basés sur les statistiques multivariées. La méthode par analyse vibratoire mesure le taux de perte en module d'élasticité dynamique (Dw_{E_n}) des rondins, qui se caractérisent par leurs imperfections géométriques.Ce travail contribue à approfondir les connaissances sur l'évaluation du niveau de dégradation du bois. Les résultats obtenus permettent d'envisager une application sur des structures réelles. Ces deux méthodes sont effectivement adaptables pour effectuer les mesures textit{in-situ}
 
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Audience level: 0.94 (from 0.93 for Reliabilit ... to 0.96 for Évaluatio ...)

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