This thesis investigates the design of masonry shell structures. Design is understood to involve two main processes; the first one is the specification of shape, form, and thickness, and the second is the justification of such choices through the analysis of its behaviour. The thesis is therefore introduced by an extensive literature review of, first of all, the relevant material properties, such as strength, stiffness, anisotropy, and bi-axial stress states, as well as of some interesting construction techniques, based on minimal or no formworkthe premise being that the contemporary adoption, or otherwise, of masonry shells as a feasible structural solution depends on the "economics" of the construction process. The analysis of the strength of masonry arches and shells is reviewed extensively, with considerable emphasis given to the validity of the application of limit analysis to masonry shells, in view of the presence of finite friction. Techniques for the form-finding of shells and for the optimisation of such forms, are then studied, and a finite-element technique developed for the finding of membrane thrust surfaces for shells incapable of carrying tension (as well as having possibly orthotropic properties). The technique is based on the solution of the partial differential equation relating shape, stress and loading, given a specific loading regime, and specific boundary conditions. The stress distribution, satisfying the given boundary and material conditions, is obtained, not on the basis of a trial-and-error approach, as is often the case, but on a plane stress analysis of the horizontal projection of the shell. The resultant shape hence automatically satisfies the boundary conditions. Various examples of the results of such method are given.

Cette contribution, en s’appuyant sur expérimentation et modélisation numérique, vise à une meilleure compréhension du comportement de structures en maçonnerie. Nous traitons tout d’abord le cas des murs soumis à un chargement hors plan de type pression uniforme. Les applications en ingénierie sont multiples, par exemple le cas de la maison individuelle construite en montagne en zone bleu, zone où les structures sont susceptibles de subir un impact de type avalanche de neige ; ou encore le cas de la maçonnerie soumise à une pression latérale induite par une charge accidentelle telle qu’une explosion dans une zone Seveso ou plus généralement en ville suite à l’explosion d’une conduite de gaz. Notre étude se confine au cas quasi-statique, l’objet étant une meilleure compréhension du comportement d’un mur en maçonnerie soumis à pression latérale uniforme. Nous avons aussi testé différentes configurations de renforcement par matériau composite. Puis nous évaluons pas à pas, les possibilités de la modélisation via la méthode des éléments discrets (DEM). Des essais judicieusement choisis, maçonnerie à joint sec ou mortier, nous permettent d’en évaluer les pertinences et les limites. Nous abordons ensuite sur maquettes, les essais sous charge ponctuelle hors plan en quasi-statique et le cas de l’impact en dynamique, puis nous traitons des essais vibratoires et des sollicitations dynamiques harmoniques. La modélisation DEM est aussi évaluée dans certains cas tels que les vibrations et les sollicitations modales, voir l’application d’une sollicitation sismique unidirectionnelle. L’étude des sollicitations dynamiques est limitée à la vibration et l’impact, plus facile à gérer en laboratoire que les essais dynamiques de « type souffle », non ici abordés mais que nous mettons en perspective. / The study, based on experiments and numerical modeling, discusses the behavior of masonry walls in the loading case of a uniform out of plane pressure. Engineering applications are multiple, for example the case of detached house built on mountain in blue area, where structures are liable to undergo an impact of snow avalanche type; or the case of masonry subjected to lateral pressure induced by accidental load such as an explosion in Seveso area or more generally in city following the explosion of a gas pipeline. Our study allows, first to quantify the bearing capacity in the case of uniform pressure in quasi-static loading case, and thus to highlight the associated modes of rupture, and secondly to estimate the improvements in terms of global behavior when the structure is reinforced by Carbon Fiber Reinforced Polymer (CFRP) layers. Then, discrete element method (DEM) is illustrated by applications to various masonry problems from simple to more complicated, where in plane loading, out of plane loading, or both, are considered. This modeling allows us to evaluate the pertinence and limitations of DEM in masonry structure. Finally we discuss the dynamic tests, with the case of impact, easier to manage in laboratory than the testing dynamic "blast type" that we will put into perspective.