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91 results on '"Laboratoire d'Etudes de Mécanique Sismique (EMSI)"'

1. Towards a model-order reduction strategy for nonlinear dynamics parametric simulations

Author: Daby-Seesaram, Alexandre, Fau, Amélie, Charbonnel, Pierre-Étienne, Néron, David, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Reduced-order model, PGD, Damage, Multi-query, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], LATIN-PGD, plasticity, Nonlinear, Dynamics, FFT
Abstract: International audience; Assessing the risk of failure of a structure subjected to seismic hazard often requires numerous costly computations. When computing fragility curves, for instance, the nonlinear damageable behaviour of structures needs to be considered, and the dynamics response of the latter must be computed for a wide range of likely ground motion inputs. This work uses a space-frequency Proper Generalised Decomposition (PGD) when solving the dynamics aspect of the history-dependent nonlinear problem, thus coupling the efficiency of model-order reduction with the numerical benefits of frequency computations. In this work, the parametric variability lies in the loading scenario, raising the need to derive a new multiquery framework to decrease the computation cost of such risk predictions. This framework relies on a wise initialisation process of the space-time nonlinear solver and the smart usage of previously computed reduced bases. The effectiveness of the method is based on the specificities of the LATIN solver used in the context of nonlinear dynamics. It is indeed the non-incremental nature of the LATIN approach that allows the use of a priori model-order reduction techniques such as the PGD as well as the spatio-temporal wise initialisation inspired from previous work on material variability in a multi-query context. This approach allows taking advantage of the redundant information embedded in the different solutions of the multiple computations scenario. The final computational cost is significantly lower than the cumulative cost of independently performing the different cases.
Published: 2023

2. A new physics-guided data assimilation framework for online structural monitoring: application to shaking table tests

Author: Diaz, Matthieu, Charbonnel, Pierre-Étienne, Chamoin, Ludovic, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)
Subjects: modified Constitutive Relation Error, Data assimilation, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, Shaking-table experiments, Kalman filtering, Earthquake Engineering
Abstract: International audience; The modified Constitutive Relation Error (mCRE) is a model updating functional whose physics-based construction avoids the explicit dependency into a priori user’s expertise. Its robustness to measurement noise and remarkable convexity properties make it a credible alternative to classical model updating methods. In recent works, the authors developed an automated mCRE-based model updating framework for the offline update of finite element models of structures submitted to ground motion inputs, before deriving it to data assimilation with the development of the Modified Dual Kalman Filter (MDKF). In the latter, we addressed sequential data assimilation by integrating the mCRE as new observer within a dual Kalman filter. Contrary to classical Kalman filters, the comparison between measurements and model predictions is achieved through the mCRE functional itself, in which the data-to-model distance is enriched with a model error term with strong mechanical content (the CRE). In this contribution, we focus on MDKF numerical improvements to achieve real-time data assimilation for structural health monitoring applications where an extensive number of parameters may need to be tracked with a few amount of data, which makes the identification process ill-posed and prone to instabilities. Using (i) parallelized mCRE computation and sigma-points propagation, (ii) the Scaled Spherical Simplex Kalman filter structure and (iii) a CRE-based clustering pre-step, CPU requirements are reduced by partial state update without loss of accuracy. The MDKF methodology and the novel key ingredients for efficient (near-optimal) data assimilation are illustrated throughout (simulated) earthquake engineering examples of growing complexity.
Published: 2023

3. An experimental test for gas pressure measurement within a realistic crack in concrete

Author: Jean-Louis Tailhan, Giuseppe Rastiello, Jean-Claude Renaud, Claude Boulay, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Nuclear and High Energy Physics, Air permeability, [SPI]Engineering Sciences [physics], Realistic crack, Nuclear Energy and Engineering, Mechanical Engineering, Fluid transfer, General Materials Science, Crack transmissivity, Safety, Risk, Reliability and Quality, Pressure drop, Waste Management and Disposal, Idealized parallel-plate crack
Abstract: Evaluating fluid leakage rates through cracks in concrete structures is essential in many fields (nuclear safety, fluid storage structures, durability of structures subjected to environmental conditions). In previous works, the authors proposed experimental procedures to study the water (Rastiello et al., 2014, 2018) and air (Tailhan et al., 2018) leakage processes through cracking concrete samples under Brazilian loading conditions. In a recent work, Tailhan et al. (2020) proposed a critical analysis of their own air permeability experimental setup considering an idealized parallel-plate system equipped with additional pressure sensors inside the crack. They showed that calibrating air flow models based on this experimental setup (and, more generally, experimental setups using “large” pressurized vessels placed upstream/downstream of the cracked sample) requires the knowledge of the pressure distribution inside the crack and that simply knowing the pressures inside the upstream and downstream chambers can lead to a misinterpretation of experimental results. In the present paper, a similar experiment is performed on a so-called “realistic crack” (i.e., representative of a crack surface in a split concrete block) molded in room-temperature-vulcanizing silicone equipped with internal pressure sensors. The results obtained show that knowing the real pressures at the inlet and outlet sections of the crack is even more important than in the case of the parallel-plate channel. Indeed, in that case, additional non-linear effects are observed in the mass flow-rate vs. square pressure gradient relation due to the geometry of the crack. Moreover, the crack geometry strongly affects the pressure drops measures at the inlet and outlet crack sections. These results clearly illustrate that attention has to be paid to interpreting experimental results on real cracks in concrete in the absence of pressure measures inside the crack. To the best of the authors’ knowledge, no experimental setups of this kind exist.
Published: 2023
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4. A hybrid frequency-temporal reduced-order method for nonlinear dynamics

Author: A. Daby-Seesaram, A. Fau, P.-É. Charbonnel, D. Néron, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: PGD, LATIN, Applied Mathematics, Mechanical Engineering, Aerospace Engineering, Transient Dynamics, Ocean Engineering, Dynamics, FFT, Reduced-order model, Damage, Control and Systems Engineering, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], LATIN-PGD, Gibbs phenomenon, Electrical and Electronic Engineering
Abstract: International audience; Solving dynamics problem in the frequency domain gives significant advantages compared with solutions fully computed in the temporal domain, but history-dependent nonlinear behaviour is an obstacle to employ that strategy. A hybrid approach is proposed to solve the nonlinear behaviour in the temporal domain, while the mechanical equilibrium is solved using a frequency strategy coupled with model-order reduction methods. In order to employ the fast Fourier transform (FFT) robustly for the transient regime, artificial numerical damping is used. The reduced-order hybrid temporal-frequency approach is investigated for two- and three-dimensional applications; it appears as a robust and proficient technique to simulate structures under transient dynamic loadings until failure.
Published: 2023
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5. Reduced T-shaped soil domain for nonlinear dynamic soil-bridge interaction analysis

Author: Maria Paola Santisi d’Avila, Luca Lenti, Stefania Gobbi, Reine Fares, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: [SPI]Engineering Sciences [physics], General Medicine
Abstract: The one-directional three-component wave propagation in a T-shaped soil domain (1DT-3C) is a numerical modeling technique, in a finite element scheme, to investigate dynamic soil-structure interaction (SSI) coupled with seismic site effects, under the assumption of vertical propagation of three-component seismic motion along a horizontal multilayered soil. A three-dimensional elasto-plastic model is adopted for soils, characterized using their shear modulus reduction curve.In this research, the 1DT-3C wave propagation modeling technique is proposed as an efficient tool for bridge design to take into account directly the spatial variability of seismic loading. This approach, in the preliminary phase of bridge study and design, allows the reduction of the soil domain and the easier definition of boundary conditions, using geotechnical parameters obtained with only one borehole investigation for each pier. This leads to a gain in modeling and computational time.
Published: 2022
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6. Analytical strain localization analysis of isotropic and anisotropic damage models for quasi-brittle materials

Author: B. Masseron, G. Rastiello, R. Desmorat, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Softening, Isotropic damage, [SPI]Engineering Sciences [physics], Mechanics of Materials, Anisotropic damage, Localization analysis, Applied Mathematics, Mechanical Engineering, Modeling and Simulation, General Materials Science, Condensed Matter Physics, Analytical method
Abstract: Strain and damage localization are usually precursors of rupture. We present a three-dimensional method dedicated to quasi-brittle materials based on the works of Bigoni & Hueckel, and Jirásek and coworkers, aiming at simplifying the analysis of the localization properties of continuous damage models of a general form, and possibly anisotropic. The method reformulates the localization problem as a two-variable polynomial maximization problem, a strategy commonly used in softening plasticity models, but not so much in Continuum Damage mechanics. The quasi-brittle hypothesis is exploited to render the problem solvable in a fully analytical way, and a post-analysis criterion for the validity of the analysis is also exhibited. In this work, the method is fully established from a theoretical viewpoint, and examples illustrating its use are provided. Multiaxial calculations are performed for four continuous damage models (two isotropic and two anisotropic ones). The method applies to induced anisotropy and constitutive models representing isotropic linear elasticity before damage growth, and remains accurate when models display immediate softening after the elastic limit (and thus to multiaxial tensile cases). The analytical method is, however, entirely general and allows for the calculation of (i) the orientation of a potential localization plane, (ii) the mode angle of the weak discontinuity, and (iii) the validity domain of such a simplified analysis.
Published: 2022
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7. Coupling spectral and Finite Element methods for 3D physic-based seismic analysis from fault to structure: Application to the Cadarache site in France

Author: Reine Fares, David Castro Cruz, Evelyne Foerster, Fernando Lopez-Caballero, Filippo Gatti, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Université Paris-Saclay, CentraleSupélec, Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), and ANR-11-RSNR-0022,SINAPS@,Séisme et Installation Nucléaire -Améliorer et Pérenniser la Sûreté(2011)
Subjects: Nuclear and High Energy Physics, Nuclear Energy and Engineering, Mechanical Engineering, [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques, General Materials Science, Safety, Risk, Reliability and Quality, Waste Management and Disposal, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire
Abstract: International audience
Published: 2022
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8. A new data assimilation framework using the modified Constitutive Relation Error for online structural monitoring: application to shaking-table experiments

Author: Diaz, Matthieu, Charbonnel, Pierre-Étienne, Chamoin, Ludovic, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)
Subjects: modified Constitutive Relation Error, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Data assimilation, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, Shaking-table experiments, Kalman filtering, Earthquake Engineering, ComputingMilieux_MISCELLANEOUS, Low-frequency dynamics
Abstract: International audience
Published: 2022

9. Reduced-order modeling methods for the construction of virtual charts in nonlinear dynamics

Author: Daby-Seesaram, Alexandre, Fau, Amélie, Charbonnel, Pierre-Étienne, Néron, David, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: [SPI]Engineering Sciences [physics], Damage, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], Nonlinear Dynamics Reduced-order modeling LATIN-PGD, LATIN-PGD, Reduced-order modeling, Nonlinear, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], Dynamics
Abstract: International audience
Published: 2022

10. Analyse modale du réacteur RES avec prise en compte du couplage fluide/structure

Author: Sigrist, Jean-François, Broc, Daniel, Lainé, Christian, DCNS Propulsion, Laboratoire d'Etudes de Mécanique Sismique ( EMSI ), Département de Modélisation des Systèmes et Structures ( DM2S ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, CSMA, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: masse ajoutée, added stiffness, fluid-structure interaction, étude sismique, [PHYS.MECA]Physics [physics]/Mechanics [physics], [ PHYS.MECA ] Physics [physics]/Mechanics [physics], seismic analysis, raideur ajoutée, added mass, interactions fluide/structure, modal analysis, analyse modale
Abstract: International audience; The present paper deals with a numerical modeling of a nuclear reactor with fluid-structure interaction phenomenon. The coupled system is modeled with an axi-symmetric 2D model; with a Fourier expansion of the problem unknowns. The mathematical formulation lies on the symmetric \mathbfu,p,φ approach. Added mass and added stiffness effects are studied and their influence on the system dynamic behavior is underlined. A temporal and spectral seismic analysis is carried out. The numerical results exposed in the study highlight fluid-structure interaction effects in the industrial case.; Le présent article expose les principes de modélisation et d'analyse sismique d'un réacteur nucléaire avec prise en compte des effets d'interactions fluide/structure. La modélisation du système couplé est réalisée en exploitant l'axi-symétrie de la géométrie et la non axi-symétrie du chargement et en proposant une représentation des inconnues du problème sous forme d'une série de Fourier. La formulation du problème couplé utilise l'approche symétrique \mathbfu,p,φ. Les effets de masse et de raideur ajoutées sont étudiés, et des résultats d'analyse sismique temporelle et spectrale sont proposés. L'ensemble des résultats de calcul permet de quantifier l'importance des phénomènes d'interactions fluide/structure pour le cas industriel.
Published: 2005

11. Efficiency of viscoelastic interstructural connections to prevent earthquake induced pounding

Author: V. Crozet, Ioannis Politopoulos, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: [SPI]Engineering Sciences [physics], business.industry, Earth and Planetary Sciences (miscellaneous), Structural engineering, Geotechnical Engineering and Engineering Geology, Active control, business, Viscoelasticity, Geology, Civil and Structural Engineering
Abstract: This work deals with the efficacy of viscoelastic connections in preventing pounding without undesirable adverse effects on the coupled structures. To this end, the earthquake response of two oscillators, coupled with optimally designed passive viscoelastic and active devices as well as with rigid connections, was studied. A particular attention was given to two issues: (a) the upper limit of the device force and (b) the capacity of the device in reducing the interstructures displacement to avoid collision. The main conclusion of the paper is that, in general, there is no substantial benefit from the use of viscoelastic connections as a means to prevent pounding.
Published: 2020
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12. Vers une stratégie robuste et automatisée pour le recalage de modèles en dynamique vibratoire : application au suivi des structures endommageantes testées sur table vibrante

Author: Diaz, Matthieu, Charbonnel, Pierre-Étienne, Chamoin, Ludovic, Laboratoire de mécanique et technologie (LMT), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Université Polytechnique Hauts-de-France [UPHF], Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S)
Subjects: Erreur en Relation de Comportement modifiée, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Essais sismiques, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, Recalage de modèle
Abstract: International audience; Dans cette étude, la stratégie de recalage de modèle basée sur la minimisation de la fonctionnelle d’Erreur en Relation de Comportement modifiée est revisitée et automatisée pour des problèmes de dynamique vibratoire. Appliquée ici à des essais sismiques sur table vibrante, la méthodologie proposée permet de suivre l’état d’une structure en corrigeant un modèle associé à partir de données issues d’une densité de capteurs limitée. Une fois validée sur la base de mesures synthétiques, la stratégie est mise en œuvre pour des mesures d’accélération réelles acquises lors de la campagne expérimentale SMART2013.
Published: 2022

13. Merging experimental design and structural identification around the concept of modified Constitutive Relation Error in low-frequency dynamics for enhanced structural monitoring

Author: M. Diaz, P.-É. Charbonnel, L. Chamoin, Diaz, Matthieu, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)
Subjects: Optimal Sensor Placement, Mechanical Engineering, Aerospace Engineering, [SPI.GCIV.DV] Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, Modified Constitutive Relation Error, Earthquake Engineering, Computer Science Applications, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Control and Systems Engineering, Structural Health Monitoring, Damage Detection, Signal Processing, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.MECA.STRU] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Civil and Structural Engineering
Abstract: International audience; The modified Constitutive Relation Error (mCRE) is a model updating functional in which structural parameters are sought alongside mechanical fields as the best trade-off between all available information given by measured data and physics knowledge, without any further assumptions. Its robustness to measurement noise and remarkable convexity properties make it a credible alternative to classical model updating methods. However, the model updating process is still conditioned by the number and location of sensing devices, which makes damage detection in SHM applications a challenging task as the available measurements are usually spatially sparse. The question of optimal sensor placement (OSP) has been largely addressed in the last decades with various strategies that aim at optimizing sensors locations either for modal analysis or structural identification. In this paper, we propose an alternative to these techniques with a new sensor placement strategy dedicated to mCRE-based model updating. It uses the concept of Information Entropy by formulating a modified Fisher information matrix, using the strong connection between mCRE and Bayesian inference. A proof of concept involving an earthquake engineering inspired academic case study, where accelerometers are positioned on a two-story frame structure subjected to random ground motion, permits to illustrate the soundness and efficiency of the proposed methodology compared to other classical OSP techniques. The influence of critical mCRE parameters is shown, as well as the benefits of taking multiple scenarios into account so as to get an OSP that is relevant for a wider range of possible damage occurrences.
Published: 2022
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14. Path-following methods for unstable structural responses induced by strain softening: a critical review

Author: Giuseppe Rastiello, Hugo Luiz Oliveira, Alain Millard, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire de Mécanique Systèmes et Simulation (LM2S)
Subjects: [SPI]Engineering Sciences [physics], Mechanics of Materials, General Materials Science
Abstract: Path-following methods for describing unstable structural responses induced by strain-softening are discussed. The main ingredients of the formalisms introduced by Riks and Crisfield for arc-length methods for geometrical non-linearities are presented. A link between two ways (monolithic and partitioned) of solving the resulting augmented equilibrium problem is discussed based on the Sherman–Morrison formula. The original monolithic approach assumes that the path-following constraint equation is differentiable with respect to the unknown displacement field and load factor. However, when dealing with material non-linearities, it is often preferred to consider constraint equations controlling the maximum of a field defined on the computational domain (e.g., a scalar strain measure, the rate of variation of an internal variable of the constitutive model). In that case, differentiability cannot be guaranteed due to the presence of the maximum operator. This makes only the partitioned formulation usable. Several path-following constraint equations from the literature are presented, and the corresponding implementations in the finite element method are discussed. The different formulations are compared based on a simple two-dimensional test case of damage localization in a beam submitted to tension. A test case involving multiple snap-backs is illustrated, finally, to show the robustness of the considered formulations.
Published: 2022
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15. Automated physics-guided data assimilation strategy for model updating in dynamics - Application to the monitoring of structures tested of shaking-tables

Author: Diaz, Matthieu, Charbonnel, Pierre-Étienne, Chamoin, Ludovic, Diaz, Matthieu, Laboratoire de Mécanique Paris-Saclay (LMPS), CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)
Subjects: [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], [SPI.GCIV.DV] Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.MECA.STRU] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph]
Abstract: International audience
Published: 2022

16. Vers une stratégie robuste et automatisée de recalage de modèle en dynamique vibratoire – Application au suivi de structures endommageantes testées sur table vibrante

Author: Diaz, Matthieu, Charbonnel, Pierre-Etienne, Chamoin, Ludovic, Laboratoire de mécanique et technologie (LMT), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)
Subjects: Model updating, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], Modified Constitutive Relation Error, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, Shaking-table experiments, ComputingMilieux_MISCELLANEOUS, Low-frequency dynamics
Abstract: International audience
Published: 2021

17. Fuzzy-driven strategy for fully automated modal analysis: Application to the SMART2013 shaking-table test campaign

Author: P.-É. Charbonnel, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Operational/experimental modal analysis, Stabilization diagram, Automation, Fuzzy clustering, Structural health monitoring, Shaking table tests, 0209 industrial biotechnology, Computer science, Mechanical Engineering, Modal analysis, Aerospace Engineering, 02 engineering and technology, 01 natural sciences, Fuzzy logic, Computer Science Applications, [SPI]Engineering Sciences [physics], 020901 industrial engineering & automation, Modal, Control and Systems Engineering, 0103 physical sciences, Signal Processing, Outlier, Earthquake shaking table, Cluster analysis, 010301 acoustics, Algorithm, Membership function, Civil and Structural Engineering
Abstract: A crucial step when identifying the modal signature of systems using growing order parametric methods consists in discriminating spurious modes from physical modes. In this paper, a three-stages clustering strategy is presented in a fuzzy framework for automating this selection process in the context of Input/Output and Output-Only identification. The novelty and strong point of the approach lies in the first stage where, after computation of single mode validation indicators, a modified fuzzy c-means clustering procedure is developed for performing a first partition. It is shown how the membership function obtained for the cluster of physical modes can be interpreted as a new synthetic modal indicator and helps with pole-splitting detection, outlier rejection and generally improves the final modal parameters estimation. The developed methodology does not involve any user-specified threshold and can be used for discriminating modes produced by any methodology consisting in fitting a growing order model to experimental data of any type. In this paper, accelerations measured during the SMART2013 shaking-table test campaign are processed using data-driven state-space identification algorithms. The automated selection process is used for tracking the modal signature of a trapezoidal shaped reinforced-concrete specimen using in turn stochastic and combined deterministic-stochastic algorithms, defining for the latter the movement of the shaking table as input. Variations in the modal signature are then correlated to the damage actually observed on the specimen and a comparison between Output-Only and Input/Output results is made in order to estimate the interaction between the specimen and the whole shaking table device.
Published: 2021
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18. Modular implementation framework of partitioned path-following strategies: Formulation, algorithms and application to the finite element software Cast3M

Author: Benjamin Richard, Ibrahim Bitar, Giuseppe Rastiello, Hugo Luiz Oliveira, Alain Millard, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Mécanique Systèmes et Simulation (LM2S), Laboratoire de Modélisation et d’Analyse de la Performance des Structures (IRSN/PSN-EXP/SES/LMAPS), Service d'Expertise des équipements et des Structures (IRSN/PSN-EXP/SES), and Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN)
Subjects: Formalism (philosophy), Computer science, business.industry, General Engineering, Modular design, Displacement (vector), Domain (software engineering), Set (abstract data type), Nonlinear system, [SPI]Engineering Sciences [physics], Software, Focus (optics), business, Algorithm
Abstract: International audience; Damaging, cracking, and strain localization mechanisms often lead to unstable structural responses characterized by snap-backs(i.e., the force and the displacement decrease simultaneously). The usual nonlinear Newton-based solution algorithms with displacement/force control cannot capture the complete equilibrium curve in a numerical context. This shortcoming can be circumventedusing path-following formulations. They rely on two hypotheses: (i) the decomposition of loading into two parts, one knownand the other unknown (only its direction is imposed); (ii) the use of path-following equations so that the unknown load (forceor displacement) contribution can be determined indirectly. Collecting the essential concepts and the formalism of path-followingarc-length methods, we design a unique framework into the Cast3M toolbox, capable of receiving existing and new path-followingequations without significant modifications. Three path-following constraints were chosen to demonstrate its applicability: a constrainton the combination of the displacement increment at a given set of nodes, a constraint on the maximum strain incrementover the computational domain, and a constraint on the maximum elastic predictor of the damage/plastic criterion function over thecomputational domain. Two- and three- dimensional strain localization simulations show that the proposed framework behaves ina stable and convergent manner, even in the presence of multiple severe snap-back instabilities. The proposed study proves helpfulbecause the user can focus on developing new path-following equations into the Cast3M toolbox. The developments discussed inthis manuscript will be made available to the users/developers community with Cast3M 2021 (release date: April 2021).
Published: 2021
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19. Structural assessment of existing reinforced concrete structures : coupling between corrosion and earthquake loading

Author: Lejouad, Chaymaa, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris-Saclay, Frédéric Ragueneau, and Benjamin Richard
Subjects: Reinforced concrete, Corrosion, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Earthquake engineering, Génie parasismique, Comportement dynamique, Campagne expérimentale, Dynamic behavior, Experimental campaign, Béton armé
Abstract: Reinforcement corrosion is one of the main causes of the decrease in the structural performance of reinforced concrete (RC) structures over time. The literature clearly reports a very limited number of experimental studies aimed at characterizing the dynamic behavior of corroded RC structures by the means of dynamic loadings.To improve the state of knowledge in terms of dynamic behavior of corroded RC structures, an experimental campaign is conducted on large-scale RC beams. These beams are corroded using an accelerated corrosion technique and subjected to quasi-static as well as dynamic loadings.From the experimental results, the evaluation of certain quantities of interest, in particular the bearing capacity, the ductility, the hysteretic capacity, the natural frequencies and the damping ratios, is carried out. Therefore, the effect of corrosion on these different quantities is revealed and the comparison between the conclusions drawn by dynamic and quasi-static tests is established.In order to capitalize the experimental campaign results, a numerical model is developed. This multifiber model, with a low computational cost, integrates certain effects of corrosion pathology, in particular the localized reduction of the corroded bars section, the degradation of the mechanical properties of the steel and the concrete cover cracking. A sensitivity study of the developed model to these different components was carried out, in comparison with the experimental results.; La corrosion des armatures est l’une des causes principales de la diminution de la performance structurale des ouvrages en béton armé au cours du temps. La littérature fait clairement état d’un nombre très limité d’études expérimentales, visant à caractériser le comportement dynamique des ouvrages en béton armé atteints de corrosion en considérant des sollicitions de nature dynamique.Pour pallier les manques relevés dans les études expérimentales antérieures, une campagne d'essai est conduite sur des poutres en béton armé de grande échelle. Ces poutres corrodées avec une technique de corrosion accélérée sont soumises à des chargements de nature quasi-statique aussi bien que dynamique.À partir des résultats expérimentaux dynamiques et quasi-statiques, l’évaluation de certaines grandeurs d’intérêt, notamment la capacité portante, la ductilité, la capacité hystérétique, les fréquences propres et les coefficients d’amortissement, est réalisée. Dès lors, l’effet de la corrosion sur ces différentes grandeurs est relevé, la comparaison entre les conclusions issues d’essais dynamiques et celles issues d’essais quasi-statiques est établie.Afin de capitaliser les résultats issus de la campagne d’essai, un modèle numérique est développé. Ce modèle multifibre, à faible coût de calcul, intègre certains effets de la pathologie de corrosion, notamment la réduction localisée de la section utile des barres corrodées, la dégradation des propriétés mécaniques de l'acier et l'état de fissuration du béton d'enrobage. Une étude de sensibilité du modèle développé à ces différentes composantes a été réalisée, en comparaison avec les résultats d’essais expérimentaux.
Published: 2020

20. Calibration of the thermo-hydro-mechanical parameters of the Callovo-Oxfordian claystone and the modelling of the ALC experiment

Author: Ruiping Guo, Darius Seyedi, K.E. Thatcher, Carlos Plúa, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA)
Subjects: International research, Important research, [SPI]Engineering Sciences [physics], Nuclear engineering, 0211 other engineering and technologies, Calibration, Environmental science, Context (language use), 02 engineering and technology, Thermal load, Geotechnical Engineering and Engineering Geology, 021101 geological & geomatics engineering, 021102 mining & metallurgy
Abstract: Andra performs a wide range of in-situ experiments at its Meuse/Haute-Marne Underground Research Laboratory (MHM URL). The purpose of these experiments is to study the feasibility of a radioactive waste repository in the Callovo-Oxfordian claystone formation (COx). An important research program has been conducted by Andra since 2005 to investigate THM response of the COx to a thermal load through laboratory and in situ experimentations. A step-by-step approach is followed, which starts with small scale heating boreholes (TED experiment) and extends to full-scale (ALC experiment). Modelling and interpretation of the TED and ALC experiments are conducted in the context of the Task E within the DECOVALEX-2019 framework. DECOVALEX-2019 is a multidisciplinary, co-operative international research effort focused on modelling coupled Thermal-Hydraulic-Mechanical-Chemical (THMC) processes. Based on the TED experiment measurements, the THM parameters of the COx are calibrated through a fully-coupled THM model using COMSOL. Then, the ALC experiment is successfully blind predicted and interpretatively modelled using the calibrated THM parameters of the COx and the proposed coupled THM model.
Published: 2020
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21. From anisotropic damage to multiple cracks by coupling a microplane model and a strong discontinuity formulation in the Embedded Finite Element Method

Author: Kakarla, Svnp Sri Hari Santosh, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris-Saclay, and Benjamin Richard
Subjects: Efem, Multiple cracks, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Microplan, Damage-To-Fracture transition, Transition endommagement-Fissuration, Éléments finis à discontinuité intégrée, Microplane model, Fissuration multiple
Abstract: The performance aspects of large scale civil engineering structures like containment facilities such as durability, serviceability and structural safety are assessed from time to time to avert any catastrophes. Also, in the cases of extreme loading, different cracking mechanisms contribute to each other ultimately leading to the failure. This creates the need for devising certain regulatory measures. In order to achieve this, it is essential to predict the information like crack opening displacements, crack spacing and tortuosity. The purpose of this thesis is to develop numerical tools to model multiple intersecting cracks. In particular, the complete strain localization process from the onset of damage to the initiation and propagation of multiple cracks. Two main ingredients are used. The microplane model allows to describe the anisotropic damage phase and Embedded Finite Element Method (EFEM) introduces cracks as multiple strong discontinuities in the damaged continuum. First, the standard EFEM is extended in the context of multiple cracks. Later, the microplane microdamage model is formulated in a thermodynamic framework using simple constitutive laws. Finally, these two approaches are coupled using a transition methodology. The proposed methodologies are illustrated using several elementary and structural test cases that involve complex stress-strain states.; Dans un contexte d’évaluation des structures en béton armé, il est d’usage d’estimer la durabilité à l’échelle du matériau, l’aptitude au service et enfin, la tenue structurale qui définit la performance de l’ouvrage considéré. Toutefois, évaluer la performance d’un élément de structure nécessite le recours à des approches numériques permettant la description voire la prédiction des principaux mécanismes dissipatifs. Par ailleurs, il est attendu de cette description que des quantités locales caractérisantes la fissuration soient accessibles numériquement, on peut citer la tortuosité, l’espacement ou encore les ouvertures associées à la fissuration. Le principal objectif de ces travaux de thèse consiste à proposer une approche permettant la description de la fissuration sous chargement cyclique. Pour cela, l’approche proposée permet de décrire le processus complet de localisation des déformations depuis l'apparition de l’endommagement jusqu’à l’initiation et la propagation de fissures multiples dans des matériaux quasi fragiles. Pour cela, la stratégie adoptée repose d’une part sur l’utilisation du modèle microplan permettant ainsi de décrire le caractère anisotrope de la fissuration et d’autre part, sur la particularisation de la méthode aux éléments finis à discontinuités intégrées. Ces deux piliers sont couplés à l’aide d’une technique de transition entre endommagement diffus et fissuration localisée. L’approche proposée est illustrée à l’aide de plusieurs exemples élémentaires. Enfin, quelques cas tests à l’échelle de l’élément de structure sont étudiés.
Published: 2020

22. Influence of Input Motion's Control Point Location in Nonlinear SSI Analysis of Equipment Seismic Fragilities: Case Study on the Kashiwazaki-Kariwa NPP

Author: Cyril Feau, Fan Wang, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Propagation of uncertainty, business.industry, Process (computing), Structural engineering, 010502 geochemistry & geophysics, Motion control, 01 natural sciences, law.invention, Nonlinear system, [SPI]Engineering Sciences [physics], Geophysics, Fragility, Geochemistry and Petrology, law, Soil structure interaction, Nuclear power plant, Sensitivity (control systems), business, Geology, 0105 earth and related environmental sciences
Abstract: The aim of this case study is to evaluate the influence of input seismic motion control point on the fragility curves of some nuclear power plant’s equipment considering (1) a strong soil–structure interaction problem and (2) the variability of the input seismic signals. To this end, a current engineering methodology was implemented for computation efficiency, based on a simplified model representing the largely embedded Unit 7 reactor building of the Kashiwazaki-Kariwa NPP (Japan). Seismic signals were generated with NGA GMPE according to the July 2007 NCOE scenario. In the process, soil non-linearity caused by each seismic signal was taken into account using the equivalent linear method. A study on the uncertainty propagation through the simplified soil–structure system is also presented. It allowed the implementation of an empirical sensitivity analysis to confirm the main results, which suggest that defining the control point of the input motion at the soil surface as prescribed in the French nuclear practice is not appropriate and may lead to biased outcomes when performing non-linear soil–structure fragility analysis. Instead, it should be defined at the “outcropping bedrock” level.
Published: 2020
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23. Partitioned path-following strategy for nonlinear structural analyses using the boundary element method

Author: Hugo Luiz Oliveira, Giuseppe Rastiello, Alain Millard, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire de Mécanique Systèmes et Simulation (LM2S)
Subjects: [SPI]Engineering Sciences [physics], Mechanics of Materials, Snap-back response, Mechanical Engineering, Computational Mechanics, General Physics and Astronomy, Path-following BEM. Nonlinear cohesive model, Computer Science Applications
Abstract: The appearance of snapping phenomena is frequent in structural analyses involving nonlinearities such as the propagation of localized damage zones, or cracks, as encountered in quasi-brittle materials. In the presence of snapping effects, the standard Newton-based algorithms cannot predict the equilibrium curves correctly by usual displacement or force control. This problem can be circumvented by using path-following techniques. This study proposes a numerical approach for nonlinear structural analysis based on the Boundary Element Method (BEM) coupled with a partitioned path-following strategy. In this strategy, the acting loads are divided into two groups: (a) those perfectly known and (b) those in which only the direction is known, while the magnitude (or load factor/multiplier) is determined to respect the equilibrium of the boundary fields (indirectly controlled) and an additional problem equation, the path-following constraint equation. The resulting nonlinear system is solved using an incremental iterative scheme. For each iteration, the corrections to the boundary fields are obtained in a partitioned manner. First, the portion coming from the unbalanced boundary fields is calculated. Then the correction resulting from a unit load in the direction of the load to be indirectly controlled is obtained. Finally, the load factor is calculated independently using the path-following constraint equation, which can be linear, nonlinear, differentiable, or not. In the numerical tests, the Control of the Nodal Displacement Increment (CNDI) is chosen as path-following constraint equation for the sake of illustration. The results show that the proposed approach can efficiently capture the equilibrium curve even in the presence of severe snap-backs. The approach is designed to be implemented in existing BEM codes straightforwardly, provided that the influence matrices can be accessed. Moreover, no additional pre-conditioning technique is required.
Published: 2022
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24. Use of response envelopes for seismic margin assessment of reinforced concrete walls and slabs

Author: Nicolas Ile, Alberto Frau, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Nuclear and High Energy Physics, Engineering, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 0211 other engineering and technologies, Shell (structure), 020101 civil engineering, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 0201 civil engineering, Structural element, Margin (machine learning), elliptical envelope, General Materials Science, Geotechnical engineering, Safety, Risk, Reliability and Quality, Waste Management and Disposal, 021110 strategic, defence & security studies, Basis (linear algebra), business.industry, Mechanical Engineering, Linear elasticity, walls, Linearity, Structural engineering, Finite element method, Stress field, Nuclear Energy and Engineering, seismic, business
Abstract: International audience; Seismic safety evaluations of existing nuclear facilities are usually based on the assumption of structural linearity. For the design basis earthquake (DBE), it is reasonable to apply a conventional evaluation of the seismic safety of building structures and carry out a linear elastic analysis to assess the load effects on structural elements. Estimating the seismic capacity of a structural element requires an estimation of the critical combination of responses acting in this structural element and compare this combination with the capacity of the element. By exploiting the response-spectrum-based procedure for predicting the response envelopes in linear structures formulated by Menun and Der Kiureghian (2000a), algorithms are developed for the seismic margin assessment of reinforced concrete shell finite elements. These algorithms facilitate the comparison of the response-spectrum-based envelopes to prescribed capacity surfaces for the purpose of assessing the safety margin of this kind of structures. The practical application of elliptical response envelopes in case of shell finite elements is based on the use of layer models such as those developed by Marti (1990), which transfer the generalized stress field to three layers under the assumption that the two outer layers carry membrane forces and the internal layer carries only the out-of-plane shears. The utility of the assessment approach is discussed with reference to a case study of a 3D structure made of reinforced concrete walls.
Published: 2017
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25. SFR mechanical scenarios and neutron transport transients with CAST3M code

Author: Grzegorz Kępisty, Daniel Broc, Guillaume Campioni, Cyril Patricot, Laboratoire de Protection d'Etudes et de Conception (LPEC), Service des Réacteurs et de Mathématiques Appliquées (SERMA), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), and Service d’Études des Réacteurs et de Mathématiques Appliquées (SERMA)
Subjects: Neutron transport, Fissile material, Computer science, 020209 energy, Nuclear engineering, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Finite element method, 010305 fluids & plasmas, Power (physics), Nuclear physics, Nuclear Energy and Engineering, Bundle, Distortion, 0103 physical sciences, Fluid–structure interaction, 0202 electrical engineering, electronic engineering, information engineering, Transient (oscillation), ComputingMilieux_MISCELLANEOUS
Abstract: In this paper we focus on of Sodium Fast Reactor core undergoing several mechanical scenarios. The mechanical full-core model in Cast3M code is described using finite elements method and Fluid-Structure Interaction is taken into account. We consider several system excitations: fluid injection, seismic excitation and compressive/opening forces applied to the bundle of assemblies. The geometry deformation is next applied for transient neutron transport simulations using a diffusion tool built in Cast3M code, named Cast3M Neutron Transport Tool (CNTT). We expose and analyze variation of power, change of fissile zone volume and assembly displacements. CNTT succeeded in code-to-code comparison using TRIPOLI-4 (a Monte Carlo code) and APOLLO3 (a deterministic code). The novelty of CNTT is the use of remeshing to take into account core distortion. The validity of assumptions applied in our approach and prospects for the future are discussed as well. The developed methodology may serve as a general tool for analysis of fast reactor systems under various mechanical excitation. Cast3M based tools provide new possibilities for safety assessments, fundamental for current and upcoming nuclear designs.
Published: 2017
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26. Étude expérimentale de l'effet de la corrosion sur le comportement dynamique de poutres en béton armé

Author: Lejouad, Chaymaa, Richard, Benjamin, Mongabure, Philippe, CAPDEVIELLE, Sophie, Ragueneau, Frédéric, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction de l'Energie Nucléaire (CEA-DEN), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN)
Subjects: [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2019

27. EXPERIMENTAL STUDY OF THE SEISMIC BEHAVIOR OF CORRODED RC BEAMS

Author: Lejouad, Chaymaa, Richard, Benjamin, Mongabure, Philippe, CAPDEVIELLE, Sophie, Ragueneau, Frédéric, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction de l'Energie Nucléaire (CEA-DEN), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN)
Subjects: [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2019

28. Assessment of the seismic behaviour of corroded RC beams: an experimental contribution

Author: Lejouad, Chaymaa, Richard, Benjamin, Mongabure, Philippe, CAPDEVIELLE, Sophie, Ragueneau, Frédéric, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN))
Subjects: [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2019

29. Shake table tests of structures subject to pounding

Author: Thierry Chaudat, Ioannis Politopoulos, V. Crozet, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: floor response spectra, [SPI]Engineering Sciences [physics], shake table test, pounding, business.industry, Earth and Planetary Sciences (miscellaneous), Earthquake shaking table, Subject (documents), Structural engineering, Geotechnical Engineering and Engineering Geology, business, Geology
Abstract: Pounding between adjacent structures during earthquakes may significantlymodify their response in terms of forces and displacements. In addition, it hasa considerable influence on acceleration and thus on floor response spectra.Therefore, pounding may be unfavorable to the response of equipment. Despiteextensive research in this field, the effects of pounding on structures are difficultto quantify accurately. This article presents results of shake table tests carried outon two representative scale adjacent structures subject to pounding. Besidesinvestigating the effects of the gap between structures and the excitation signal,this study examines also the effect of tying the two structures together by meansof rigid links to suppress pounding. The results of the experimental campaign arethen compared with those of numerical simulations. Analyses and experimentalresults show good agreement regarding both impact forces and interstorey drifts
Published: 2019
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30. A step-by-step global crack-tracking approach in E-FEM simulations of quasi-brittle materials

Author: Ejona Kishta, Francesco Riccardi, Benjamin Richard, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), and ANR-11-RSNR-0022,SINAPS@,Séisme et Installation Nucléaire -Améliorer et Pérenniser la Sûreté(2011)
Subjects: Mathematical optimization, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Structural level, Differential equation, Perturbation (astronomy), 02 engineering and technology, Discontinuity, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Brittleness, 0203 mechanical engineering, Applied mathematics, General Materials Science, Cast3M, 0101 mathematics, Navier–Stokes equations, Mathematics, Partial differential equation, Computer simulation, Tracking, Mechanical Engineering, Finite element method, 010101 applied mathematics, Fracture, 020303 mechanical engineering & transports, Mechanics of Materials, Concrete
Abstract: International audience; The numerical simulation of two-dimensional fracture processes of quasi-brittle materials by means of the Embedded Finite Element Method is dealt with. Attention is paid to the coupling with the global crack-tracking strategy, which has been proposed in the literature in the form of a heat conduction-like problem. It turns out that the stiffness-like matrix associated with this formulation is singular and a numerical perturbation has to be introduced in order to overcome the ill-posedness of the problem. The dependence of the solution on this parameter may represent a limitation for the global tracking approach. Furthermore, it is found that if the root of each discontinuity is not updated during an incremental analysis, a loss of continuity of the crack path may appear when principal stress directions rotate. This paper aims to provide a solution to the aforementioned issues. An alternative mathematical formulation of the problem is thus given in terms of Navier-Stokes equations, linking the diffusive contribution to a characteristic mesh length. Additionally, a modified crack-tracking algorithm, considering the evolution of the root for the identification of the crack path, is proposed. The numerical assessment of the proposed tracking strategy is reported by means of benchmark tests at the structural level.
Published: 2017
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31. CastLab: an object-oriented finite element toolbox within the Matlab environment for educational and research purposes in computational solid mechanics

Author: Romili Paredes, Cédric Giry, Francesco Riccardi, Giuseppe Rastiello, Chaymaa Lejouad, Eliass Zafati, Santosh Kakarla, Benjamin Richard, Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Modélisation et d’Analyse de la Performance des Structures (IRSN/PSN-EXP/SES/LMAPS), Service d'Expertise des équipements et des Structures (IRSN/PSN-EXP/SES), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Institut de Radioprotection et de Sûreté Nucléaire (IRSN)
Subjects: Object-oriented programming, Computer science, business.industry, General Engineering, 02 engineering and technology, 01 natural sciences, Finite element method, Toolbox, 010101 applied mathematics, [SPI]Engineering Sciences [physics], 020303 mechanical engineering & transports, 0203 mechanical engineering, Computational mechanics, Solid mechanics, Feature (machine learning), Key (cryptography), 0101 mathematics, MATLAB, Software engineering, business, computer, Software, ComputingMilieux_MISCELLANEOUS, computer.programming_language
Abstract: International audience; The Matlab environment has become widely used among the computational mechanics community, not only for research purposes but also to teach either undergraduate or graduate classes. This paper aims to present a new toolbox devoted to computational mechanics and in particular to solid mechanics. Both recent and well-established numerical formulations have been implemented in it. One of its strengths resides in the fact that it was developed within an object-oriented framework. This key feature makes the CastLab toolbox easy-to-use and with extensive capabilities for customized user developments. After a brief description of the theoretical background related to the problems that can be solved by means of the toolbox, several representative case-studies are presented. These examples have been selected to illustrate not only the numerical efficiency of the toolbox, which is of primary importance for research purposes, but also its strong educational and pedagogic potential.
Published: 2019
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32. Experimental and numerical analyses of variability in the responses of imperfect slender free rigid blocks under random dynamic excitations

Author: Cyril Feau, Laurent Baillet, Michel Fogli, Charlie Mathey, David Clair, École normale supérieure - Cachan (ENS Cachan), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Laboratory of Research and Applications in Advanced Mechanics, French Institute of Advanced Mechanics and Blaise Pascal University, LRAAM, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: 021110 strategic, defence & security studies, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Stochastic process, 0211 other engineering and technologies, Motion (geometry), 020101 civil engineering, 02 engineering and technology, Mechanics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Seismic tests, Out-of-plane motion, 0201 civil engineering, Rigid block, statistical validation, Rocking, Overturning, Earthquake shaking table, Point (geometry), Defects, Sensitivity (control systems), Imperfect, Excitation, Civil and Structural Engineering, Mathematics, Block (data storage)
Abstract: International audience; Due to the well-known sensitivity of the behaviors of free structures under seismic excitations, the question of the aptitude of a numerical model to accurately represent them arise. To contribute to the answer to this question, this article presents experiments which were carried out on the shaking table of CEA/Saclay in France, on three rigid blocks with geometrical defects, inevitably due to the manufacturing process, subjected to 100 realizations of a random process. These tests were analyzed using specifically-developed indicators, and compared with the results yielded by two numerical models, one with a symmetrical geometry and the other with a non-symmetrical geometry, calibrated to reproduce out-of-plane behavior identified through release tests. Counter-intuitively, this article shows that a numerical model can predict motion over a longer period than an experiment performed on a supposedly identical block. From a statistical point of view, despite experimental uncertainties this article shows a good agreement between numerical and experimental results. Finally, a numerical study, performed using artificial seismic signals, showed that the assumption of perfect geometry can lead to an underestimation of the risk of overturning. Moreover, it is showed that a symmetrical model with a realistic slenderness correction can provide an overestimation of this risk under 1D excitation, but not in 2D.
Published: 2018
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33. SMART 2013: Lessons learned from the international benchmark about the seismic margin assessment of nuclear RC buildings

Author: François Voldoire, Maxime Fontan, Thierry Chaudat, Salim Abouri, Nicolas Bonfils, Jacky Mazars, Benjamin Richard, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), EDF (EDF), OXAND, Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), ANR-13-IS02-0001,SMArT,Satisfaisabilité Modulo Arithmétique et Théories(2013), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Peak ground acceleration, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 0211 other engineering and technologies, 020101 civil engineering, 02 engineering and technology, Shear walls assembly, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 0201 civil engineering, Seismic analysis, 021105 building & construction, Cast3M, Aftershock, Civil and Structural Engineering, SMART, business.industry, Seismic loading, Torsion (mechanics), Numerical models, Structural engineering, shaking table tests, Reinforced concrete, Nuclear power plant, Seismic safety margins, Earthquake shaking table, business, Geology, Reinforced Concrete
Abstract: International audience; In this paper, the main findings and conclusions drawn from the second international benchmark named SMART 2013 and jointly organized by the French Sustainable Energies and Atomic Energy Commission (CEA) and Electricité De France (EDF) within the framework of a wide research program entitled “Seismic design and best-estimate Methods Assessment for Reinforced concrete buildings subjected to Torsion and nonlinear effects” (SMART) are presented. A 1:4-scaled reinforced concrete (RC) specimen, representing a part of a nuclear auxiliary building and designed according to French guidelines for a PGA level equal to 0.2 g, was subjected to shaking table tests; results of this experimental campaign are used as reference data for this benchmark. The input ground motions considered in the seismic loading sequence are mainly natural bi-axial signals (main shock and aftershock) recorded during the Northridge earthquake that took place in California, USA in 1994 and have a PGA (Peak Ground Acceleration) about 1.8 g. These high-intensity seismic loadings allow assessing the relevancy of nonlinear numerical models when they have to deal with strong nonlinearities due to concrete cracking. The results produced by the 42 teams which participated in the international benchmark show that (i) the dynamic behavior of the specimen is well captured when dealing with the design level, (ii) the displacement are underestimated when dealing with the beyond design behavior, (iii) the peak frequency shifts are well captured and (iv) the damaging effect of the Northridge aftershock is almost null. Last, seismic safety margins of the specimen are quantified by two mechanical indicators; the results confirm the fact that the RC specimen which was designed according to the codes applicable in the French nuclear industry, exhibits noticeable good performance level regarding collapse prevention.
Published: 2018
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34. Floor response spectra of a partially embedded seismically isolated nuclear plant

Author: Ioannis Politopoulos, Ion Sergis, Fan Wang, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Engineering, Soil–structure interaction, Embedment, business.industry, Foundation (engineering), Soil Science, Seismic isolation, Structural engineering, Nuclear power, Geotechnical Engineering and Engineering Geology, Spectral line, Finite element method, law.invention, [SPI]Engineering Sciences [physics], law, Soil structure interaction, Nuclear power plant, Rocking excitation, Floor response spectra, business, Excitation, Civil and Structural Engineering
Abstract: International audience; This paper deals with the effects of foundation embedment on the floor response spectra of big base isolated structures such as nuclear power plants. Analyses of a finite element model, representative of a real nuclear power plant, have been carried out. It has been demonstrated that, in agreement with previous work, base rocking excitation, induced by soil–structure interaction, may amplify the non-isolated modes׳ response and thus it must not be overlooked.
Published: 2015
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35. Accelerometer, Velocimeter Dense‐Array, and Rotation Sensor Datasets from the Sinaps@ Postseismic Survey (Cephalonia 2014–2015 Aftershock Sequence)

Author: Cécile Cornou, Alberto Frau, Nikolaos Theodoulidis, Armand Mariscal, Fabrice Hollender, Vincent Perron, Edward Marc Cushing, Régis Cottereau, Agisilaos Konidaris, Philippe Langlaude, Angkeara Svay, Alexandros Savvaidis, Aurore Laurendeau, Pierre-Yves Bard, Sébastien Hok, Chrisostomos Andreou, Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire de mécanique des sols, structures et matériaux (MSSMat), Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec, IRSN/PRP-DGE/SCAN/BERSSIN (BERSSIN), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Instituto Geofísico, Escuela Politécnica Nacional, Escuela Politécnica Nacional, Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Bureau d'évaluation des risques sismiques pour la sûreté des installation (IRSN/PRP-DGE/SCAN/BERSSIN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), and Escuela Politécnica Nacional (EPN)
Subjects: 021110 strategic, defence & security studies, Dense array, Rotation sensor, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 0211 other engineering and technologies, 02 engineering and technology, 010502 geochemistry & geophysics, Geodesy, Accelerometer, 01 natural sciences, Geophysics, Geology, Aftershock, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Sequence (medicine)
Abstract: International audience
Published: 2018
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36. A new semi-active control based on nonlinear inhomogeneous optimal control for mixed base isolation

Author: Ioannis Politopoulos, Sette Diop, Duc Chuan Vu, Human Genetics Division (Mp 808), Laboratoire des signaux et systèmes (L2S), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: 021110 strategic, defence & security studies, Engineering, Computer simulation, business.industry, 0211 other engineering and technologies, 020101 civil engineering, 02 engineering and technology, Building and Construction, Interval (mathematics), Optimal control, Displacement (vector), 0201 civil engineering, Damper, [SPI.AUTO]Engineering Sciences [physics]/Automatic, Nonlinear system, [SPI]Engineering Sciences [physics], Autoregressive model, Mechanics of Materials, Control theory, Base isolation, business, Civil and Structural Engineering
Abstract: International audience; This paper presents a control algorithm for seismic mixed base isolation, combining passive isolators and semi-active viscous dampers. The objective is to limit base displacement while avoiding undesirable amplification of the response of the non-isolated modes. To this end, the proposed algorithm takes into account the constraints on the damping coefficient of the semi-active damper and information on the excitation. It is based on the approximate iterative solution, at each control time step, of a nonlinear inhomogeneous constrained optimal control problem. An autoregressive model is used to obtain, at each control time step, a prediction of the upcoming excitation in a short time interval ahead. Numerical simulation results demonstrate the efficacy of the above method, especially in improving floor response spectra, and its superiority with respect to clipped-optimal algorithms.
Published: 2018
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37. Dissipations in reinforced concrete components Static and dynamicexperimental identification strategy

Author: Thomas Heitz, A. Le Maoult, Frédéric Ragueneau, Cédric Giry, B. Richard, CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de mécanique et technologie (LMT), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Damping ratio, RC beam, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Computer science, 0211 other engineering and technologies, 020101 civil engineering, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Damping, 0201 civil engineering, Atomic energy commission, Set (abstract data type), 021105 building & construction, TAMARIS, ComputingMilieux_MISCELLANEOUS, Civil and Structural Engineering, business.industry, Structural engineering, Dissipation, Reinforced concrete, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Nonlinear system, Identification (information), IDEFIX, Earthquake shaking table, [SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations, business
Abstract: International audience; Despite their now well documented drawbacks, viscous damping based models to describe the dissipationsoccurring in reinforced concrete (RC) structures during seismic events are popular among structural engineers.Their computational efficiency and their convenient implementation and identification are indeed attractive. Ofcourse, the choice of a viscous damping model is, most of the time, reasonable, but some questions still arisewhen it comes to calibrate its parameters how do these parameters evolve through the nonlinear time-historyanalysis? How do they interact when several eigenmodes are involved? To address these questions, the IDEFIXexperimental campaign (French acronym for Identification of damping-dissipations in RC structural elements) hasbeen carried out on RC beams set up on the Azalee shaking table of the TAMARIS experimental facility operatedby the French Alternative Energies and Atomic Energy Commission (CEA). First, this experimental campaign ispositioned within an overview of related experimental campaigns in the literature. Second, the IDEFIX experimental campaign is presented. In particular, noticeable results are given by examples of first post-treatments,including an improved so-called areas method, which lead to very different identified damping ratio depending on the method used.
Published: 2018
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38. Strong discontinuity analysis of a class of anisotropic continuum damage constitutive models ? Part I: Theoretical considerations

Author: Frédéric Ragueneau, Ejona Kishta, Benjamin Richard, Cédric Giry, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Mécanique et Technologie (LMT), and École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Continuum (measurement), Continuous modelling, Mechanical Engineering, Mathematical analysis, Isotropy, Geometry, 02 engineering and technology, Kinematics, Classification of discontinuities, Condensed Matter Physics, 01 natural sciences, Finite element method, 010101 applied mathematics, 020303 mechanical engineering & transports, Discontinuity (geotechnical engineering), 0203 mechanical engineering, Mechanics of Materials, Displacement field, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], General Materials Science, 0101 mathematics, ComputingMilieux_MISCELLANEOUS, Civil and Structural Engineering, Mathematics
Abstract: Several modeling techniques aiming at considering cracks as kinematics discontinuities have been proposed for the past years. Within this scope, the embedded finite element method (E-FEM) was introduced a couple of years ago. Among the features of this approach, it has been shown that a kinematic enhancement of the displacement field allows constructing a discrete model (expressed in terms of traction vector–displacement jump) from any continuous model (expressed in terms of stress–strain). This result has been rigorously established if the continuous model is formulated within the framework of either isotropic continuum damage or plasticity theories. The objectives of this study are (i) to extend this result in case where the continuous model belongs to a class of anisotropic continuum damage constitutive models and (ii) to show the main features of a specific traction/separation law derived from the aforementioned class of constitutive models through several numerical case-studies. In this paper, the light is put on the theoretical considerations which allow deriving discrete models in a consistent way.
Published: 2017
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39. Asymptotic formulae for the risk of failure related to an elasto-plastic problem with noise

Author: Laurent Mertz, Cyril Feau, Mathieu Laurière, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: stochastic variational inequalities, Risk analysis, General Mathematics, 010102 general mathematics, Elasto plastic, 01 natural sciences, 010101 applied mathematics, Noise, elasto-plastic oscillator, [SPI]Engineering Sciences [physics], Donsker Invariance Principle, Statistics, Applied mathematics, 0101 mathematics, white noise, Mathematics
Abstract: The risk of failure of mechanical structures under random forcing is an important concern in earthquake engineering. For a class of simple structures that can be modeled by an elasto-plastic oscillator, the risk of failure can be expressed in terms of the probability that, on a certain interval of time, the plastic deformation goes beyond a threshold related to a failure zone. In this note, asymptotic formulae for the risk of failure of an elasto-perfectly-plastic oscillator excited by a white noise are proposed. Our approach exploits the long cycle (repeating pattern) property of the aforementioned oscillator as introduced in A. Bensoussan, L. Mertz, S.C.P. Yam, Long cycle behaviour of the plastic deformation of an elasto-perfectly-plastic oscillator with noise, C. R. Acad. Sci. Paris Ser. I, 2012. We show that asymptotically the plastic deformation behaves like a Wiener process for which analytical formulae are available. Our result is a consequence of the Anscombe–Donsker Invariance Principle. Numerical experiments and comments are carried out.
Published: 2017
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40. A discrete anisotropic damage constitutive law with an enhanced mixed-mode kinematics: Application to RC shear walls

Author: Ejona Kishta, Cédric Giry, Benjamin Richard, Frédéric Ragueneau, Mikel Balmaseda, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), and ANR-11-RSNR-0022,SINAPS@,Séisme et Installation Nucléaire -Améliorer et Pérenniser la Sûreté(2011)
Subjects: Materials science, Constitutive equation, 02 engineering and technology, Classification of discontinuities, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph], 01 natural sciences, Displacement (vector), Discontinuity (geotechnical engineering), 0203 mechanical engineering, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Shear wall, General Materials Science, 0101 mathematics, ComputingMilieux_MISCELLANEOUS, business.industry, Mechanical Engineering, Mechanics, Structural engineering, Finite element method, 010101 applied mathematics, Cracking, 020303 mechanical engineering & transports, Mechanics of Materials, Fracture (geology), business, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire
Abstract: The concept of displacement discontinuities embedded into standard finite elements allows efficient modeling of regions exhibiting localized strains, e.g. fracture of quasi-brittle materials. The present paper addresses the issue of fine cracking representation and the formulation of an enhanced anisotropic model to capture anisotropic cracking failure of reinforced concrete specimens. A damage-based constitutive law accounting, in a natural manner, for particular crack families orientation is used. This latter is enhanced with a mixed-mode strong discontinuity kinematics providing a discrete model expressed in terms of the displacement jump. The formulation and the finite element implementation are described. A shear wall under cyclic loading is studied. The results obtained are compared to the experimental ones. It is shown that the proposed model succeeds in reproducing accurately the anisotropic cracking and the unilateral effect.
Published: 2017
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41. Toward an integrated seismic risk assessment for nuclear safety improving current French methodologies through the SINAPS@ research project

Author: Thomas Chartier, Ejona Kishta, Julie Régnier, Nadim Moussallam, Frédéric Ragueneau, Cédric Guyonnet-Benaize, Fabian Bonilla, Marc Nicolas, François Voldoire, Silvano Erlicher, Pierre-Yves Bard, Vincent Perron, Fabrice Hollender, Fabien Banci, Irmela Zentner, Panagiotis Kotronis, Alain Le Maoult, Nikolaos Theodoulidis, Benjamin Richard, Angkeara Svay, Stéphane Grange, Aurore Laurendeau, Fernando Lopez-Caballero, M. Lancieri, Catherine Berge-Thierry, Régis Cottereau, Laboratoire de mécanique des sols, structures et matériaux (MSSMat), Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec, Laboratoire de Détection et de Géophysique (CEA) (LDG), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), CEA Cadarache, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA-CESTA), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction de l'Energie Nucléaire (CEA-DEN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, EDF (EDF), Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), AREVA, Groupe AREVA, Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Risques, Vulnérabilité des structures et comportement mécanique des matériaux (RV), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), EGIS, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Equipe-projet MOUVGS (Cerema Equipe-projet MOUVGS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Séismes et Vibrations (IFSTTAR/GERS/SV), Communauté Université Paris-Est-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), SINAPS@ ANR-11-RSNR-0022,SINAPS@,SINAPS@: Séisme & Installations Nucléaires: Assurer et Pérenniser la Sûreté, CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Risques, Vulnérabilité des structures et comportement mécanique des matériaux (RV ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), ANR-11-RSNR-0022,SINAPS@,Séisme et Installation Nucléaire -Améliorer et Pérenniser la Sûreté(2011), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), and Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Communauté Université Paris-Est
Subjects: Nuclear and High Energy Physics, Engineering, 010504 meteorology & atmospheric sciences, Design strategy, 010502 geochemistry & geophysics, 7. Clean energy, 01 natural sciences, Civil engineering, Construction engineering, Seismic analysis, law.invention, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], law, Vulnerability assessment, Multidisciplinary approach, Nuclear power plant, General Materials Science, Seismic risk, Safety, Risk, Reliability and Quality, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, business.industry, Mechanical Engineering, Seismic hazard, Nuclear Energy and Engineering, 13. Climate action, business, Risk assessment
Abstract: International audience; The Tohoku earthquake and associated tsunami in March 2011 caused a severe nuclear accident at the Fukushima Daiichi Nuclear Power Plant, where level 7 (International Atomic Energy Agency (IAEA) – INES scale) meltdown at three reactors occurred. The underestimation of the seismic and tsunami hazards has been recognized and the seismic margins assessment of the nuclear plants remains a priority for the whole nuclear community. In this framework a five-year research project called SINAPS@ (Earthquake and Nuclear Installations: Ensuring and Sustaining Safety) is currently on-going in France. A reliable estimate of seismic margins is possible only if all uncertainties, epistemic and aleatory, are effectively identified, quantified and integrated in the seismic risk analysis. SINAPS@ brings together a multidisciplinary community of researchers and engineers from the academic and the nuclear world. SINAPS@ aims at exploring the uncertainties associated to databases, physical processes and methods used at each stage of seismic hazard, site effects, soil and structure interaction, structural and nuclear components vulnerability assessments, in a safety approach: the main objective is ultimately to identify the sources of potential seismic margins resulting from assumptions or when selecting the seismic design level or the design strategy. The whole project is built around an “integrating” work package enabling to test state-of-the-art practices and to challenge new methodologies for seismic risk assessment: the real case of Kashiwazaki-Kariwa Japanese nuclear plant, shocked by the severe earthquake in 2007 provided a rich dataset which will be used to compare with the predictions. The present paper proposes for each step of the seismic risk analysis a review of the state of practice in France in the nuclear field and then precise the objectives and research strategy of SINAPS@ to overcome identified limitations or weaknesses. Scientific issues are illustrated through preliminary results of the project.
Published: 2017
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42. How are the equivalent damping ratios modified by nonlinear engineering demand parameters?

Author: Frédéric Ragueneau, Benjamin Richard, Cédric Giry, Thomas Heitz, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, amplexor, amplexor, École normale supérieure - Rabat (ENS Rabat), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: [PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Damping matrix, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Constitutive equation, 0211 other engineering and technologies, 020101 civil engineering, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 0201 civil engineering, Control theory, TAMARIS, 021101 geological & geomatics engineering, Mathematics, Linear model, System identification, Dissipations, Decoupling (cosmology), Mechanics, Dissipation, Reinforced concrete, Viscous damping, Model identification, Nonlinear system, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, Earthquake shaking table, Experiments
Abstract: International audience; When attempting to predict the seismic response of reinforced concrete (RC) structures , a trade-off has to be found out between a realistic representation of the dissipations through material behavior law and a numerically more efficient modeling with a controlled computational demand such as a Rayleigh-type damping model. Anyway, constitutive laws only describe internal dissipation and actually need a complementary dissipation term often chosen as a proportional damping matrix to take into account external dissipation sources such as interactions with the environment. Decoupling these two contributions in global dissipation measurement from experimental tests is still challenging. To address this problem, a numerical study based on an experimentally identified structural model is here presented. To this end, an experimental campaign has been carried out on RC beams set up on the AZALEE shaking table of the TAMARIS experimental facility operated by the French Alternative Energies and Atomic Energy Commission (CEA). In this paper, the experimental campaign is first presented. Secondly, a suited constitutive model is formulated and identified from the experimental results. Third, numerical dynamic experiments are carried out in order to assess the influence of several parameters on the energy dissipation and on the equivalent viscous damping ratio through two different methods. The validity of these results is assessed on a numerical case where a nonlin-ear model and an equivalent linear model are compared with each other. Experimental results of dynamic tests are also used as reference in order to estimate the additional viscous damping necessary to take into account the whole energy dissipation.
Published: 2017

43. Strong discontinuity analysis of a class of anisotropic continuum damage constitutive models – Part II: Concrete material application

Author: Frédéric Ragueneau, Benjamin Richard, Cédric Giry, Ejona Kishta, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: Engineering, Induced anisotropy, Constitutive equation, 0211 other engineering and technologies, 02 engineering and technology, 0203 mechanical engineering, Robustness (computer science), [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], General Materials Science, Anisotropy, ComputingMilieux_MISCELLANEOUS, 021101 geological & geomatics engineering, Civil and Structural Engineering, Mathematical logic, Continuum (measurement), business.industry, Continuous modelling, Mechanical Engineering, Mathematical analysis, Structural engineering, 16. Peace & justice, Condensed Matter Physics, 020303 mechanical engineering & transports, Mechanics of Materials, Jump, business
Abstract: On the basis of the strong discontinuity analysis, a discrete model expressed in terms of traction vector-displacement jump has been constructed from a continuous model expressed in terms of stress–strain law. In the first part of the paper, this approach has been extended to a class of anisotropic continuum damage constitutive models [1] . In this second part of the paper, the proposed class of discrete anisotropic damage constitutive models is particularized. More precisely, a micromechanical-based anisotropic damage constitutive model is derived. This model accounts in a natural manner for particular crack families orientation. The aims of this paper are (i) to illustrate the capabilities of the proposed discrete enhanced model in reproducing the induced anisotropy appearing in quasi-brittle materials when cracking and (ii) to assess the numerical robustness of the time integration scheme. For this purpose, two numerical examples at the material point level are exposed after a brief presentation of the time integration scheme. The correspondence between the continuous and the discrete model as well as the induced anisotropy features are emphasized.
Published: 2017
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44. Fretting wear of a nitrided 316L/304L contact subject to in-phase normal force fluctuation in dry and lithium-boron solution: An R P -friction energy wear approach

Author: C. Phalippou, O. Graton, Habibou Maitournam, E. Marc, Siegfried Fouvry, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne (ENISE)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D)
Subjects: Work (thermodynamics), Normal force, Materials science, Tribocorrosion, Metallurgy, Fretting, 02 engineering and technology, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Surfaces, Coatings and Films, [SPI]Engineering Sciences [physics], 020303 mechanical engineering & transports, 0203 mechanical engineering, Volume (thermodynamics), Mechanics of Materials, Phase (matter), Materials Chemistry, Cylinder, Composite material, 0210 nano-technology, Nitriding, ComputingMilieux_MISCELLANEOUS
Abstract: In nuclear power plants, tubes of the rod cluster control assemblies undergo impacts at low contact pressures against guides, causing specific wear on the contact surfaces. The present study investigates fretting wear behavior under variable loading, using an original double-actuator fretting wear system which allows independent control of tangential sliding and normal force fluctuation. Using this test system the fretting wear response of a nitrided 316L SS cylinder fretted against a 304L SS plate in air and in a lithium-boron solution is investigated. The effect of normal force fluctuations quantified using the R P = P min / P max ratio was investigated keeping constant the tangential sliding amplitude. Surface damage evolution was followed by 3D profilometry and several analyses were conducted on specimen surface and cross-sections (SEM, EDX). To quantify the wear volume extension, an R P -weight friction-energy-wear parameter (i.e., R P η × Σ E d ) is introduced. This new loading parameter allows us to take into account both friction work and normal force fluctuation. For a dry interface the η exponent was found to be very small (0.15) suggesting that the wear volume is directly related to the friction energy dissipated in the interface. In contrast, in lithium-boron solution the best fitting was achieved with η w = − 0.9 which implies an energy wear rate nearly inversely proportional to R P . The larger the normal force fluctuation (i.e., the smaller R P ) the larger the contribution of tribocorrosion and the faster the surface wear. Besides, unexpected erosion-corrosion wear phenomena were identified at the inlets of the contact. These different wear mechanisms are discussed and quantified.
Published: 2017
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45. Damping identification and quantification: experimental evidences and first numerical results

Author: Thomas Heitz, Benjamin Richard, Cedric Giry, Frédéric Ragueneau, Alain Le Maoult, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: experimental campaign, [SPI.GCIV]Engineering Sciences [physics]/Civil Engineering, damping, RC structures, model identification, Cast3M
Abstract: International audience; The way of quantifying energy dissipations in reinforced concrete (RC) structures during seismic events is still a complex issue to solve out. However, the designer would rather use simplified modelling for both the geometrical representation of the structure and its mechanical behaviour. To this end, the Rayleigh-type viscous damping based models are commonly used even if several studies have emphasized the inherent issues of this approach. Alternative solutions exist, but the target values of the damping themselves are still questionable since the dynamic properties of the structure evolve throughout the nonlinear time history analysis. To bring answers to the aforementioned issues, a set of experiments including seismic tests on RC beams is carried out by means of the TAMARIS experimental facility operated by the French Alternative Energies and Atomic Energy Commission (CEA). The results will be used to propose a new damping modelling strategy able to reproduce damping evolution throughout time history analysis while avoiding the use of complex constitutive laws. In this paper, the lacks of Rayleigh damping models are briefly reminded and a review of the advantages and disadvantages of various damping measurement experimental procedures is made. Then, the IDEFIX experimental campaign (not executed yet) is presented in contrast with the aforementioned review. Eventually, numerically simulated results of the tests are exposed and discussed. Preliminary numerical results in connection with the proposed damping modelling strategy will be shown and compared with the ones coming from existing approaches in order to demonstrate not only its relevance but also its efficiency.
Published: 2017

46. Anisotropic continuum damage constitutive model to describe the cyclic response of quasi-brittle materials: The regularized unilateral effect

Author: Benjamin Richard, Eliass Zafati, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire - IRSN [Fontenay-aux-Roses], Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), and ANR-11-RSNR-0022,SINAPS@,Séisme et Installation Nucléaire -Améliorer et Pérenniser la Sûreté(2011)
Subjects: [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Computer science, Constitutive equation, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Operator function theory, Crack closure, Brittleness, 0203 mechanical engineering, Damage mechanics, Anisotropic damage, medicine, General Materials Science, Statistical physics, Continuum mechanics, Continuum (measurement), Applied Mathematics, Mechanical Engineering, Stiffness, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Finite element method, Nonlinear system, 020303 mechanical engineering & transports, Mechanics of Materials, Modeling and Simulation, medicine.symptom, 0210 nano-technology
Abstract: International audience; Within the framework of damage mechanic, numerous anisotropic damage models have been proposed in the literature with the aim to represent the anisotropic degradation of quasi-brittle materials. The benefits from such models arise from the fact they are consistent with the principles of the continuum mechanics enabling easy numerical implementation in the majority of finite element codes. Despite the wealth of anisotropic models in the literature, further developments are needed to simulate correctly the responses involving phenomena related to crack closure. The present paper proposes a new class of anisotropic damage models characterized by its capabilities to describe non linear progressive stiffness recovery with the possibility to introduce permanent strains. The theoretical framework takes benefits from some results of the operator function theory. Further mathematical features are established for sets of functions, which are termed opening (closure) cracking functions. These features are useful to control the material behavior when the tensile or the compressive strains are activated (deactivated) with more or less smoothness. The thermodynamical admissibility condition is fulfilled, as long as the damage variable and the cracking functions satisfy further conditions. The robustness associated with the time integration of the proposed class of models is illustrated by a structural case study.
Published: 2017
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47. Behavior of rigid blocks with geometrical defects under seismic motion: an experimental and numerical study

Author: Mathey, Charlie, Feau, Cyril, Politopoulos, Ioannis, Clair, David, Baillet, Laurent, Fogli, Michel, École normale supérieure - Cachan (ENS Cachan), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Mécanique et Ingénieries (LAMI), Institut Français de Mécanique Avancée (IFMA)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Laboratory of Research and Applications in Advanced Mechanics, French Institute of Advanced Mechanics and Blaise Pascal University, and LRAAM
Subjects: rocking, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], rigid block, defects
Abstract: International audience; the present work investigates the influence of small geometrical defects on the behavior of slender rigid blocks. A comprehensive experimental campaign was carried out on one of the shake tables of CEA/Saclay in France. The tested model was a massive steel block with standard manufacturing quality. Release, free oscillations tests as well as shake table tests revealed a non‐negligible out‐of‐plane motion even in the case of apparently plane initial conditions or excitations. This motion exhibits a highly reproducible part for a short duration that was used to calibrate a numerical geometrically asymmetrical model. The stability of this model when subjected to 2000 artificial seismic horizontal bidirectional signals was compared with the stability of a symmetrical one. This study showed that the geometrical imperfections slightly increase the rocking and overturning probabilities for earthquake signals in a narrow range of peak ground acceleration.
Published: 2016
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48. CONTRIBUTION TO STRUCTURAL VULNERABILITY QUANTIFICATION: FROM THE REPRESENTATIVE VOLUME ELEMENT TO THE MEMBER SCALE

Author: Richard, Benjamin, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris Saclay, and Alain Combescure
Subjects: interface acier/béton, modèle lattice, constitutive model, [SPI.MECA.MSMECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Materials and structures in mechanics [physics.class-ph], seismic margins, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph], steel/concrete interface, strong discontinuities, matériaux quasi-fragiles, loi de comportement, discontinuité forte, génie parasismique, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], quasi-brittle materials, marges sismiques, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, earthquake engineering, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire, discrete element approach
Abstract: This memoir is the synthesis of research activities I have conducted over the past decade aiming at improving the numerical description of some dissipative mechanisms at the material scale and quantifying the vulnerability of reinforced concrete structures. The main objectives of the research presented in this dissertation are: (i) to improve both the predictive capabilities and the numerical robustness of the time integration strategies of the continuous constitutive model when dealing with the cyclic behavior of quasi-brittle materials subjected to either long-term or short-term loadings, (ii) to improve numerical techniques capable of describing the discontinuous nature of cracking and related local dissipative phenomena, and (iii) to contribute to the definition of large-scale experimental campaigns and to organize international workshops aiming to better understand the complex behavior of reinforced concrete structures when subjected to extreme loadings, such as earthquakes. In the first part, we focus on the development and validation of a continuous constitutive model to describe the mechanical behavior of quasi-brittle materials subjected to cyclic loadings. Simplified strategies are also derived from full three-dimensional approaches to serve probabilistic techniques aiming at taking into account uncertainties and updating mechanical models. In the second part, some light is shed on some developments aiming at better quantifying the cracking features. Then, the results of experiments designed to assess the dynamic response of strongly asymmetric reinforced concrete structures are presented. The experimental data have led to numerical studies shared with the international scientific community. The lessons learned from this research is then employed to design research projects we plan to work on over the next few years.
Published: 2016

49. CONTRIBUTION TO STRUCTURAL VULNERABILITY QUANTIFICATION

Author: Richard, Benjamin, Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris Saclay, and Alain Combescure
Subjects: interface acier/béton, modèle lattice, constitutive model, [SPI.MECA.MSMECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Materials and structures in mechanics [physics.class-ph], seismic margins, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph], steel/concrete interface, strong discontinuities, matériaux quasi-fragiles, loi de comportement, discontinuité forte, génie parasismique, [SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph], [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], quasi-brittle materials, marges sismiques, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, earthquake engineering, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire, discrete element approach
Abstract: This memoir is the synthesis of research activities I have conducted over the past decade aiming at improving the numerical description of some dissipative mechanisms at the material scale and quantifying the vulnerability of reinforced concrete structures. The main objectives of the research presented in this dissertation are: (i) to improve both the predictive capabilities and the numerical robustness of the time integration strategies of the continuous constitutive model when dealing with the cyclic behavior of quasi-brittle materials subjected to either long-term or short-term loadings, (ii) to improve numerical techniques capable of describing the discontinuous nature of cracking and related local dissipative phenomena, and (iii) to contribute to the definition of large-scale experimental campaigns and to organize international workshops aiming to better understand the complex behavior of reinforced concrete structures when subjected to extreme loadings, such as earthquakes. In the first part, we focus on the development and validation of a continuous constitutive model to describe the mechanical behavior of quasi-brittle materials subjected to cyclic loadings. Simplified strategies are also derived from full three-dimensional approaches to serve probabilistic techniques aiming at taking into account uncertainties and updating mechanical models. In the second part, some light is shed on some developments aiming at better quantifying the cracking features. Then, the results of experiments designed to assess the dynamic response of strongly asymmetric reinforced concrete structures are presented. The experimental data have led to numerical studies shared with the international scientific community. The lessons learned from this research is then employed to design research projects we plan to work on over the next few years.
Published: 2016

50. Relaxation base seismic isolator

Author: Vu, Duc Chuan, Politopoulos, Ioannis, Diop, Sette, Human Genetics Division (Mp 808), Laboratoire des signaux et systèmes (L2S), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et Sûreté Nucléaire (IRSN), Laboratoire d'Etudes de Mécanique Sismique (EMSI), Service d'Etudes Mécaniques et Thermiques (SEMT), Département de Modélisation des Systèmes et Structures (DM2S), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Modélisation des Systèmes et Structures (DM2S), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay
Subjects: [SPI]Engineering Sciences [physics], [SPI.AUTO]Engineering Sciences [physics]/Automatic
Abstract: International audience; This paper deals with the use, for seismic applications, of a Maxwell element in parallel with a low damping isolator. The study of the properties of the frequency response function shows that this isolator is capable to reduce the base displacement of isolated structures with no considerable amplification of the non‐isolated modes. This is, also, confirmed by the floor response spectra under earthquake excitations. Hence, the previously mentioned isolator does not present the drawbacks met when base displacement is reduced by increasing damping. Moreover, it seems that its performance is comparable with that of more elaborated and expensive techniques combining passive and semi‐active devices.
Published: 2016
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