Résumé
Until the 19th century, masonry was the preferred long-term construction method. Today, questions about the conservation of old buildings and their serviceability in post-fire situations remain unanswered. The fire at Notre-Dame de Paris Cathedral in 2019 makes this a particularly topical issue. It was the occasion to develop a new numerical approach for structural analysis of masonry, combining FEM and DEM approaches. The Finite Element Method (FEM) makes it possible to consider pre-peak and post-peak mechanical properties of the material. The Discrete Element Method (DEM) allows the behaviour of the joints to be modelled accurately. These two numerical approaches have been combined in a "hybrid" model using the LMGC90 (DEM) and CAST3M (FEM) codes. The aim of the study presented here is to test the hybrid model under a fire-like thermal loading. An assembly of two blocks joined by mortar was first studied. Then, experimental data from the literature were used to validate the model on a real case. These experimental tests consisted of heating one side of a 3x3 m² wall with a standard ISO 834 fire, while the other side was exposed to ambient temperature. The materials used in these tests were similar to those used in the Notre-Dame de Paris Cathedral: Lutetian limestone and hydraulic lime mortar. The results are used to improve the hybrid model and its application with a view to the calculation of Notre-Dame de Paris Cathedral post-fire stability.