scope:

INTRODUCTION

This design guide is an update to the AISC publication Torsional Analysis of Steel Members and advances further the work upon which that publication was based: Bethlehem Steel Company's Torsion Analysis of Rolled Steel Sections (Heins and Seaburg, 1963). Coverage of shapes has been expanded and includes W-, M-, S-, and HP-Shapes, channels (C and MC), structural tees (WT, MT, and ST), angles (L), Z-shapes, square, rectangular and round hollow structural sections (HSS), and steel pipe (P). Torsional formulas for these and other non-standard cross sections can also be found in Chapter 9 of Young (1989).

Chapters 2 and 3 provide an overview of the fundamentals and basic theory of torsional loading for structural steel members. Chapter 4 covers the determination of torsional stresses, their combination with other stresses, Specification provisions relating to torsion, and serviceability issues. The design examples in Chapter 5 illustrate the design process as well as the use of the design aids for torsional properties and functions found in Appendices A and B, respectively. Finally, Appendix C provides supporting information that illustrates the background of much of the information in this design guide.

The design examples are generally based upon the provisions of the 1993 AISC LRFD Specification for Structural Steel Buildings (referred to herein as the LRFD Specification). Accordingly, forces and moments are indicated with the subscript u to denote factored loads. Nonetheless, the information contained in this guide can be used for design according to the 1989 AISC ASD Specification for Structural Steel Buildings (referred to herein as the ASD Specification) if service loads are used in place of factored loads. Where this is not the case, it has been so noted in the text. For single-angle members, the provisions of the AISC Specification for LRFD of Single-Angle Members and Specification for ASD of Single- Angle Members are appropriate. The design of curved members is beyond the scope of this publication; refer to AISC (1986), Liew et al. (1995), Nakai and Heins (1977), Tung and Fountain (1970), Chapter 8 of Young (1989), Galambos (1988), AASHTO (1993), and Nakai and Yoo (1988).

The authors thank Theodore V. Galambos, Louis F. Geschwindner, Nestor R. Iwankiw, LeRoy A. Lutz, and Donald R. Sherman for their helpful review comments and suggestions.