Modelling the thermal response of timber is a primary issue for the assessment of the mechanical resistance of timber structures exposed to fire. Therefore, this paper analyses various advanced calculation methods of determining the charring rate. Authors of this contribution use analytical calculation methods according to two different publications and also a numerical calculation by means of program based on Finite Element Method (FEM). Input values of parameters in these calculations were derived from an experiment on a timber-concrete beam, which was realised by two authors of this paper in the past. In conclusion, the values of onedimensional charring rate of timber calculated by different methods are compared. It is necessary to pay attention to the fact that the resultant values can significantly differ depending on various input values in the analytical calculations. The charring rate increases until a certain time at the beginning of the charring and then it starts to slightly decrease. However, not all of the calculation methods presented in this paper correspond with that.

Pri rôznych rozmeroch trhlín môže dochádzať k zmenšeniu reziduálneho prierezu a tým aj mechanickej odolnosti. V tomto článku je analyzovaná rýchlosť uhoľnatenia drevených prvkov s rôznymi trhlinami. Vzorky sú vystavené tepelnému toku v kónickom kalorimetri. Cieľom článku je popísať experiment drevených vzoriek s trhlinami a analyzovať výsledky získané pomocou numerickej analýzy. Z predbežných analýz vyplýva, že trhliny môžu mať signifikantný vplyv na uhoľnatenie dreva v mieste trhliny a v prípade viacerých trhlín v priereze na celý prierez.

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Description of historical covered bridge over Hnilec river so called bottom bridge in Gelnica near the station. History of the bridge. Way of construction of the bridge. Its structural system. Photographs of the bridge and its details. Scheme of the bridge.

Eurocode 5, Part 1-2 for the design of timber structures in fire conditions contains two simplified methods and advanced calculation methods, as well. The first method is the reduced cross-section method, which is the recommended procedure in Eurocode 5, Part 1-2. The second method is the reduced properties method. There are differences in results between these two methods. These methods are designated for evaluation of the mechanical resistance of timber members and there is a calculation of the charring depth by means of these simplified rules. Moreover, there are advanced calculation methods. These advanced methods deal with the determination of the charring depth, the thermal response model and the structural response model. They can be used for members, parts of a structure or entire structures. This paper presents differences between these simplified and advanced methods and the comparison of results.