Comparison of the load-bearing capacity of reinforced concrete columns under fire conditions using the method A, zone method and isotherm 500 method

摘要

This paper presents validation and evaluation of usefulness of three non-advanced methods in EN 1992-1-2 used to determine the load-bearing capacity of columns under fire conditions: the method A, the isotherm 500 degrees C method, and the zone method. To verify the usefulness of these methods, experimental results for columns tested in the fire laboratories in Ottawa, Braunschweig, Liege and Ghent were used. The FDM was used to calculate the cross-section temperature distribution being required in the 500 degrees C isotherm method and the zone method. Temperature dependent material parameters of concrete and steel were adopted according to Eurocode 2. In the case of lack of information in the standards, the authors' own assumptions were proposed and described. The calculated fire resistance times were compared with the experimental results. The method A has proved to be accurate enough and safe for the cases fulfilling its limitations. The results obtained with the 500 degrees C isotherm method vary significantly from the experimental results. The zone method is the most complex of these three methods and provides the results more accurate and safer than those obtained with the 500 degrees C isotherm method. The zone method is recommended for verification of the load-bearing capacity of reinforced concrete columns under fire conditions.