Effective Length and Notional Load Approaches for Assessing Frame Stability

This report provides a thorough understanding of the assumptions with respect to column and frame stability made in the American Institute of Steel Construction (AISC) specifications and presents the derivation and use of one alternate approach that is in common use in some form within several other design standards. Of the three techniques for stability design discussed, two approaches are based on the use of effective length factors and the third method involves the use of a notional load approach.

Examples are included to illustrate the procedures for both common and unusual conditions encountered in practice, along with discussions on the advantages and disadvantages of each of the methods. This report is applicable to both unbraced and braced frames having either fully-restrained or partially-restrained connections.