Analysis of the Effect of Gypsum-Based Fire Protection Cover on Charring of Wooden Bearing Elements

Fire resistance of load-bearing wooden structures is evaluated by the charring of surface layers of wooden bearing elements. The degree of resistance is determined by the onset and course of charring; these basic parameters are affected by the cover structure as well as by cavity fillers between the individual bearing elements. This article focuses on analysing the structure of fire protection covers based on gypsum boards, namely gypsum plasterboards and gypsum fibreboards. The foundation for the current analysis, based on the ignition temperature of the load-bearing timber element under the fire cover, includes the results of experimental fire tests carried out on test specimens in a fire furnace with a standard time-temperature curve set to simulate a fire. In addition, a numerical analysis of the temperature behaviour in the structure was carried out in order to compare the experimental results with the values obtained by mathematical analysis. Finally, the influence of the cover layers on the resulting fire resistance of the analysed structures is evaluated.