NUMERICAL SIMULATION OF FIRE SPREADING IN A TWO-STOREY RESIDENTIAL BUILDING

A CFD tool is used to simulate a full-scale two-storey residential building subjected to a typical domestic fire. The detailed numerical simulation of the occurring physical and chemical phenomena allows the investigation of the developing flow-field, the fire spreading characteristics, as well as the thermal behaviour of the construction materials. The FDS code is used to simulate the turbulent, multicomponent and reactive flow-field developing inside the building. The examined building is constructed using a structural steel frame configuration with dry-wall systems. The internal and external walls consist of various layers of gypsumboard, cementboard and insulating materials. When a gypsumboard is subjected to a high temperature environment, water molecules bound in its crystal lattice are released and transferred through the board, absorbing energy and thus reducing the mean wall temperature; this process is known to enhance the fire resistance characteristics of the structure. The actual thermo-physical properties of all the construction and furniture house materials are taken into account, in order to accurately describe their thermal behaviour. The simulated 152 m2 two-storey building is considered to be completely furnished according to a standard residential configuration. The fire resistance behaviour of the building is evaluated by considering three realistic alternative ventilation scenarios. Numerical predictions of the temporal evolution of various parameters such as gas velocity, gas and wall temperatures, toxic gas concentrations and smoke movement are obtained for the entire domain that represents the interior of the building. Gas velocity and temperature predictions are used to visualize the developing flow-field and to estimate the heat flux that each building element is exposed to. Predicted wall temperatures allow the assessment of the steel frame – dry-wall construction technique in terms of fire resistance.