This ANSI-approved Specification has been developed by consensus through ANSI-accredited procedures to provide uniform practice in the design of steel frame buildings and other structures. It is intended to provide design criteria for common uses, rather than for low frequency problems, which tend to occur across the spectrum of structural analysis. This Specification is the result of the consensus deliberation of a committee of highly experienced and professionally recognised structural engineers representing a wide geographic distribution within the United States. The committee includes approximately an equal number of engineers from regulatory agencies and private practice, engineers involved in research and teaching, as well as engineers employed by steel producing companies. The contribution and assistance of more than 50 additional professional volunteers, who work on the task committees, is also acknowledged. The Symbols, Glossary, Abbreviations and Annexes of this Specification are an integral part of the Specification. The Commentary, which is not mandatory, has been prepared to provide a better understanding of the provisions of the Specification and its consultation by the user is encouraged. In addition, notes have been incorporated throughout the Specification to guide the user, which are of a non-mandatory nature, providing practical and concise information for the application of the provisions. A significant number of technical modifications has been made since the 2010 edition of this Specification, including:
- Adoption of ASTM F3125 bolt specification, which includes Grades A325, A325M, A490, A490M, F1852 and F2280.
- The adoption of new ASTM specifications for HSS pipe materials, ASTM A1085/ A1085M and A1065/A1065M, which allow the use of a design thickness equal to the full nominal thickness of the member.
- Expansion of structural integrity provisions applicable to connection design.
- Incorporation of the shear lag factor for welded plates or elements connected with longitudinal welds of different lengths.
- The available compressive strength for double angles and T-sections is determined by the general flexural-torsional buckling equation for members without slender elements.
- Incorporation of limit states for torsional buckling with restrained axis for members with lateral bracing offset from the shear center.
- Review of the formulation of the available compressive strength for members with slender compression elements.
- Reformulation of the bending strength provisions available for T-sections and double angles.
- Review of the shear resistance in the web of certain I-sections and channels, both when including and not including the tensile field action.
- Increase of the strength limit in reinforcing bars to 5600 kgf/cm2 (80 ksi) for composite columns.
- Incorporation of provisions to apply the direct analysis method to composite members.
- General requirements were added to address the minimum composite action in composite beams.
- Review of bolt arrangements in combination with welds.
- The minimum pretension was increased for bolts of 28 mm (11/8") in diameter and larger.
- The standard hole sizes and the widths of the short slot and long slot holes for bolts of 25 mm (1") in diameter and larger have been increased.
- Reorganization of connection design provisions for HSS tubular sections in Chapter K, including references to Chapter J for some of the limit states.
- Provisions were expanded in Annex 1 for direct modelling of member imperfections and inelasticity that can be employed in the direct analysis method.
- A table of high strength bolt properties at elevated temperatures was added in Annex 4.
The reader is cautioned that good professional judgment should be employed if data or recommendations pertaining to this Specification are used, as described in greater detail in the note preceding this preface.