The behavior of mechanically loaded hollow brick masonry walls when exposed to fire is investigated numerically. A multi-scale thermo-mechanical model based on the Arlequin framework is developed. Plate models are used in the brick's walls and coupled to accommodated 3D models in the brick's corners. This is a first achievement in this work. The thermo-mechanical multi-scale coupling and treatment is a second one. Numerical results are given to enlighten our achievements