Design of Steel Columns in Unbraced Frames Using Notional Loads

Abstract

This paper summarizes for practitioners the key recommendations of a recent ASCE report for utilizing the notional load approach to design steel columns in unbraced frames. This method, which has been employed successfully outside the United States, involves the addition of a lateral load to each story and column line that is proportional to the total gravity load applied to it at that level. The main advantage of the notional load approach is that it eliminates the need to calculate effective length factors. Sway stability effects are accounted for by increasing the applied moments in the beam-column interaction equations, rather than by reducing the axial capacity.