Design of steel columns in case of fire

This article covers the assessment of the load carrying behavior of centrically loaded columns made of double symmetric H-sections at elevated temperatures. After a short description of the general load carrying behavior in the event of fire, imperfection factors are presented which allow a reliable design using the current model of DIN EN 1993-1-2. The imperfection factors were developed with the help of validated numerical calculation models for temperatures between 100 degrees C and 700 degrees C. A comparison shows that using the imperfection factors of the code leads to unsafe results when "buckling perpendicular to the weak axis" is considered. Whereas, the results for lower temperatures (< 300 degrees C) are partly uneconomical. In addition, geometrical imperfections are derived from the imperfection factors, which allow a second order analysis with elastic material behavior.