- Author
-
Ranby, A.
- Title
- Structural Fire Design of Thin Walled Steel Sections.
- Coporate
- Lulea University of Technology, Stockholm, Sweden
- Report
-
Thesis; 1999:05; LTU-LIC-99/5-SE
1999
143 p.
- Keywords
-
structural design
|
steels
|
temperature
|
walls
|
failure
|
load bearing elements
|
building design
|
building construction
|
steel columns
- Identifiers
- local buckling of thin walled steel plates and columns; flexural buckling of thin walled steel columns; torsional-flexural buckling of thin walled steel columns; model for load bearing fire resistance of thin walled steel columns
- Abstract
- New design solutions have to be developed that can fulfil higher requirements to building quality, environment and total economy. A load bearing structure of thin walled steel sections has the possibility to fulfil these requirements and therefore, there is a growing interest in using such structures in both apartment blocks and residential houses. New design methods and products have resulted in environmental steel frame buildings with high U-values and good sound insulation. The aim of this thesis is to study the structural fire behaviour of thin walled steel sections; to find the actual steel temperature; how it varies across the steel sections and the phenomena of local buckling at elevated steel temperatures. The flexural buckling and torsional-flexural buckling load bearing resistances have also been studied. By using this information a method to design thin walled steel columns at elevated temperature has been developed. When calculating the load bearing resistance of thin walled steel columns at elevated temperatures, it is necessary to know the actual distribution of steel temperatures. This has been solved by using the software of Super-Tasef. The temperature calculation results have been verified by comparison to different tests. Results show that the agreement is quite acceptable. The phenomena of initial deflections and local plate buckling resistance at elevated steel temperatures are described and estimated by a theory of Nylander. Different empirical estimates show that the results are fairly consistent. The resistance is numerically estimated by an FE analysis, using a non-linear solution procedure. The numerical analysis shows results rather in accordance with the empirical solutions. These results have also been verified by comparisons to tests. The load bearing resistance of thin walled steel columns depends on local and global buckling, including flexural and torsional-flexural buckling. Calculations have been done according to StBK-N5, Swedish Code for Light-Gauge Metal Structures and Eurocode 3, Part l-3. Equivalent numerical calculations have then been done using FE analysis. These results have been verified by tests as well.