Exploratory Research on the Thermal Properties of Wood in Real Fire Conditions

As construction material, wood represents a response to concerns over the environmental impact caused by steel and concrete. A good performance of timber structural members must be demonstrated in fire. To perform numerical simulations of timber structures under elevated temperatures, EN1995-1-2 provides effective thermal properties of wood for computing the temperature distribution. These properties have been determined considering the standard time-temperature curve. The aim of the exploratory research is to verify to what extent these properties may be considered also for natural fires, by adapting the real exposure conditions within the numerical simulations. In the tests performed at the University of Liège, timber samples were subjected on one side to heat fluxes of different intensities, including decreasing phases. Time-temperature curves inside the samples were recorded by thermo-couples inserted at different distances from the exposed side. Using SAFIR software, dedicated to the analysis of structures under elevated temperatures, the temperature distribution within the samples was calculated considering thermal properties provided by EN1995-1-2. The comparison with the experimental results emphasized that the correspondence is not satisfactory for all cases.