The Safety of Steel Columns

by Reidar Bjorhovde, (M.ASCE), Assoc. Prof. of Civ. Engrg.; The Univ. of Alberta, Edmonton, Alberta, Canada,

Serial Information: Journal of the Structural Division, 1978, Vol. 104, Issue 3, Pg. 463-477

Document Type: Journal Paper


Traditional design of steel columns is analyzed with a view towards actual and assumed factors of safety. It is shown that due to the variation of strength that is caused by the randomness of the column strength parameters, the real margins of safety differ from what is prescribed by the design specifications. A study of several typical column shapes shows that realistic factors of safety vary between 1.4 and 2.1, as compared to the assumed values of 1.67 to 1.92. Column design improvements are evaluated, and it is shown that an approach that involves the use of several (multiple) column curves is particularly feasible. The development of such curves in the United States is described, and it is shown that the differences between real and assumed column strength values will be significantly diminished. The traditional factor of safety concept is analyzed, and an alternative approach suggested that will lead to consistent and uniform levels of safety. This development is put in perspective by a formulation that allows its use in load and resistance factor design.

Subject Headings: Steel columns | Load and resistance factor design | Structural strength | Safety | Curvature | Parameters (statistics) | Comparative studies | Cold-formed steel | United States

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