Alternative Approaches for Elastic Analysis and Design of Steel Frames. I: Overview

Abstract

Two methods for analysis and design of steel framing systems are outlined and compared to the current American Institute of Steel Construction (AISC) load and resistance factor design (LRFD) buckling solution or effective length based procedure: an AISC LRFD based notional load approach and a modified elastic approach. Both methods provide a rational means of accounting for the key phenomena that affect system strength, specifically residual stresses (i.e., member inelasticity) and initial geometric imperfections. By accounting for these factors directly within a second-order elastic analysis, the need for effective length factors or buckling solutions is eliminated. Also, these methods provide a more accurate estimate of required internal system forces than current methods. Examples of solutions for a stability critical industrial-type frame are presented to illustrate the application of these methods, and to compare and contrast their results with solutions from both the current AISC LRFD procedures and from rigorous distributed plasticity analysis.