Micromodeling

International audience; Masonry is one of the oldest construction materials and is still commonly used today to build houses or structures because of its strength, solidity, durability, resistance, its elegant appearance, etc. However, masonry, which is not generally thought to be a highly technological material, shows highlycomplex behavior, due in particular, to the interactions between the components (mortar, bricks) and the anisotropy induced by the direction of the joints, which are a source of weakness. Masonry structures were classically designed on the basis of empirical rules. Modern virtual methods of design have been developed only quite recently. Structures built long ago were extremely stable because they were massive. In modern masonry buildings, the walls are very thick, requiring the stability to be studied from a theoretical point of view, especially when wind or earthquakes are a concern. The strength of the masonry is thus critical and it is necessary to study the solidity of the structure using fine models and numerical simulations as in the case of concrete and steel structures. Other problems such as cracks also require more detailed studies on the design of masonry structures. Mortar joints are usually weaker than masonry units, which explains the existence of planes of weakness along which cracks can propagate. Several models have been developed and presented in the literature for studying and predicting the behavior of masonry structures. Depending on the level of accuracy and simplicity required, either macro- or micromodeling strategies can be used for this purpose. [...]