This Specification is based upon past successful usage, advances in the state of knowledge, and changes in design practice. The 2016 American Institute of Steel Construction’s Specification for Structural Steel Buildings provides an integrated treatment of allowable strength design (ASD) and load and resistance factor design (LRFD), and replaces earlier Specifications.
As indicated in Chapter B of the Specification, designs can be made according to either ASD or LRFD provisions. This ANSI-approved Specification has been developed as a consensus document using ANSI-accredited procedures to provide a uniform practice in the design of steel-framed buildings and other structures. The intention is to provide design criteria for routine use and not to provide specific criteria for infrequently encountered problems, which occur in the full range of structural design.
This Specification is the result of the consensus deliberations of a committee of structural engineers with wide experience and high professional standing, representing a wide geographical distribution throughout the United States.
The committee includes approximately equal numbers of engineers in private practice and code agencies, engineers involved in research and teaching, and engineers employed by steel fabricating and producing companies. The contributions and assistance of more than 50 additional professional volunteers working in task committees are also hereby acknowledged. The Symbols, Glossary, Abbreviations and Appendices to this Specification are an integral part of the Specification.
A nonmandatory Commentary has been prepared to provide background for the Specification provisions and the user is encouraged to consult it. Additionally, nonmandatory User Notes are interspersed throughout the Specification to provide concise and practical guidance in the application of the provisions. A number of significant technical modifications have also been made since the 2010 edition of the Specification, including the following:
• Adopted an ASTM umbrella bolt specification, ASTM F3125, that includes Grades A325, A325M, A490, A490M, F1852 and F2280 • Adopted new ASTM HSS material specifications, ASTM A1085/A1085M and A1065/ A1065M, that permit use of a design thickness equal to the full nominal thickness of the member • Expanded the structural integrity provisions applicable to connection design • Added a shear lag factor for welded plates or connected elements with unequal length longitudinal welds • The available compressive strength for double angles and tees is determined by the general flexural-torsional buckling equation for members without slender elements • Added a constrained-axis torsional buckling limit state for members with lateral bracing offset from the shear center • Revised the available compressive strength formulation for members with slender compression elements • Reformulated the available flexural strength provisions for tees and double angles