Modélisation probabiliste et validation expérimentale du transfert thermique et du comportement thermomécanique avec endommagement d'une plaque multicouche carton-plâtre-carton soumise au feu

PARIS-EST Marne-la-Vallee-BU (774682101) / SudocSudocFranceF

A limit analysis approach based on Cosserat continuum for the evaluation of the in-plane strength of discrete media: application to masonry

International audienceIn the frame of Cosserat continuum theory, an upscaling procedure for the assessment of the in-plane strength domain of discrete media is developed. The procedure is the extension to the Cosserat continuum of a procedure initially formulated for the Cauchy continuum, based on the kinematic approach of limit analysis and the classical homogenisation theory. The extension to the Cosserat continuum is made in order to take into account the effect of particles' rotation on the strength of the discrete medium. The procedure is illustrated with regard to periodic assemblies of blocks in contact and is then generalised to the whole class of discrete periodic media with particles of the same type. The case of masonry is considered as an application. Strength criteria of columns and walls are formulated in terms of non-symmetric stresses and in-plane couples. The procedure allows to show how the in-plane strength of the medium is reduced as a result of particles' rotation

Resistance to explosion assessment of an electric transformer building

The ability of technical buildings to resist internal explosions produced by short circuits occurring in electrical transformers is an issue for the public authorities. Even if the probability of such an event is very low, the consequences can be significant and can easily put the surrounding public in danger due the blast, the projection of fragments and to the subsequent very toxic fire. The aim of this article is to investigate the consequences the blast on the structure of the technical building in which the transformer is located. The first part of this study deals with the estimation of the pressure load on the walls of the transformer’s building. A complete modelling of the phenomenology is proposed starting from the electrical energy delivered into the arc, its transformation into gases, the efforts applied through the liquid onto the casing of the container, the expansion of the gases inside the building, the blast wave produced and its interaction on the inner walls of the building. In particular, the characteristics (amplitude and duration) of the shock waves are evaluated using the modelling tool ‘DIFREX’, developed by INERIS. This tool considers the evolution of the shock waves intensity, during their propagation and their reflection on obstacles (like walls). The overpressure signals and their time evolution are calculated according to an optimized spatial discretization in order to get the worst case for the structure. The second part describes the modelling of the building structure using SAP2000 software in order to evaluate its dynamic behaviour and estimate the internal forces induced by the explosion. The structural behaviour depends mainly on the characteristic duration of the overpressure and the overall stiffness of the building. The calculation is performed according a dynamic transient analysis. The results in terms of displacement and the effect on the reinforcement are given