Marcus Vinicius Girão de Morais

Contribution à l'explication de l'éclatement de certains éléments en béton soumis à une température élevée

ABSTRACT We study the behavior of concrete subjected to high temperature. It aims to explain the spalling phenomenon observed during experiments. Mechanical computations are carried out with the finite element code CAST3M developed at the French Atomic Energy Agency (CEA). The stresses are expressed according to the heat gradient and water vapor pressure inside the specimens, preliminary evaluated using thermo-hydrous calculations. The generated mechanical stresses are calculated according to two assumptions of behavior: the linear isotropic elastic law and an elasto-plastic model. Numerical simulations show that, during the heating cycles, tension stresses are developed in the central part of the cylindrical specimens and compression stresses at their surface. The higher stresses appear when the surface temperature of the specimens is about 300 °C. The numerical tension stresses in the specimens then exceed the concrete tensile strength.