The “Allowable Stress Design” method has long
been used for the design of steel structures in the
United States. 13233 Recently, the probability-based
Load and Resistance Factor Design (LRFD) criteria
have been successfully applied to the structural design
of hot-rolled steel shapes and built-up
member^.^ The AIS1 LRFD Specification is being
developed as well for the design of structural members
cold-formed from carbon and low alloy steel^.^
The LRFD criteria offer an improved approach for
the design of steel structures because they involve
probabilistic considerations for uncertain variables in
the design formulas.