A Model Specification for Stability Design by Direct Analysis

This paper presents a model specification for stability design by direct analysis. It is based on the stability provisions of the 2005 AISC Specification, rewritten around the Direct Analysis Method alone. The material is presented in the language and format of the AISC Specification, including "User Notes" and the italicizing of terms listed in the glossary where they first appear in a section. The focus on a single method has offered the opportunity to expand some of the provisions beyond what is in the current AISC Specification, both to improve clarity and to address issues that have arisen from use of the document. Where this involved substantive changes, they are explained in an appendix to this paper (Appendix A). A second appendix (Appendix B) outlines the purpose or physical significance of each of the important steps in the Direct Analysis Method by showing the correlation of these steps to the basic requirements for design of structures for stability. The "traditional" Effective Length Method is included in the correlation to show how that method differs from the Direct Analysis Method. A third appendix (Appendix C) provides guidance to the user on the modeling of structures for the application of the Direct Analysis Method.