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PREFACE

The AISC Load andResistance Factor Design (LRFD) Specification for Structural Steel Buildings is based on reliability theory. As have all AISC Specifications, this Specification has been based upon past successful usage, advances in the state of knowledge, and changes in design practice. This Specification has been developed as a consensus document to provide a uniform practice in the design of steel-framed buildings. 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 U.S. 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 15 task committees are also hereby acknowledged.

The Symbols, Glossary, and Appendices to this Specification are an integral part of the Specification. A non-mandatory Commentary has been prepared to provide background for the Specification provisions and the user is encouraged to consult it.

The principal changes incorporated in this edition of the Specification include:

• Dual units format. Values and equations are given in both U.S. customary and metric units. The metric conversions (given in parentheses following the U.S. units) are based on ASTM E380, Standard Practice for Use of the International System of Units (SI). The equations are non-dimensionalized where possible by factoring out material constants, such as E and G.

• Inclusion of new structural steels ASTM A913 and A992.

• Additional notch toughness requirements for complete-joint-penetration groove welds with tension applied normal to the effective area.

• New provisions for stability bracing of beams, columns, and frames.

• New Chapter N for evaluation of existing structures.

• Revised provisions for member design under fatigue loading in Appendix K.

• eorganization of material on pin-connected members and eyebars.

• evised provisions for concrete-encased beams.

• ew limitation on the stud reduction factor when a single stud is used in a rib.

• evised bolt bearing strength criteria.

The reader is cautioned that professional judgment must be exercised when data or recommendations in the Specification are applied, as described more fully in the disclaimer notice preceding this Preface.