ANSI/AISC 341-05 ANSI/AISC 341s1-05 An American National Standard Seismic Provisions for Structural Steel Buildings Including Supplement No. 1 Seismic Provisions for Structural Steel Buildings dated March 9, 2005 and Supplement No. 1 dated November 16, 2005 Supersedes the Seismic Provisions for Structural Steel Buildings dated May 21, 2002 and all previous versions Approved by the AISC Committee on Specifications and issued by the AISC Board of DirectorsAMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC. One East Wacker Drive, Suite 700 Chicago, Illinois 60601-1802
6.1–iii PREFACEThis Preface is not a part of ANSI/AISC 341-05, Seismic Provisions for Structural SteelBuildings, but is included for informational purposes only.The AISC Specification for Structural Steel Buildings (ANSI/AISC 360-05) is intended tocover common design criteria. Accordingly, it is not feasible for it to also cover all of thespecial and unique problems encountered within the full range of structural design practice.This document, the AISC Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341-05) with Supplement No. 1 (ANSI/AISC 341s1-05) (hereafter referred to as the Provisions)is a separate consensus standard that addresses one such topic: the design and construction ofstructural steel and composite structural steel/reinforced concrete building systems for high-seismic applications. Supplement No. 1 consists of modifications made to Part I, Section 14of the Provisions after the initial approval had been completed.These Provisions are presented in two parts: Part I is intended for the design and constructionof structural steel buildings, and is written in a unified format that addresses both LRFDand ASD; Part II is intended for the design and construction of composite structural steel/reinforced concrete buildings, and is written to address LRFD only. In addition, sevenmandatory appendices, a list of Symbols, and Glossary are part of this document. Termsthat appear in the Glossary are generally italicized where they first appear in a sub-section,throughout these Provisions. A nonmandatory Commentary with background information isalso provided.The previous edition of the AISC Seismic Provisions for Structural Steel Buildings,approved on May 21, 2002, incorporated many of the advances achieved as part of theFEMA/SAC program and other investigations and developments related to the seismicdesign of steel buildings. Recognizing that rapid and significant changes in the knowledgebase were occurring for the seismic design of steel buildings, especially moment frames, theAISC Committee on Specifications committed to generating frequent supplements to theProvisions. This commitment was intended to keep the provisions as current as possible.These Provisions were modified to be consistent with SEI/ASCE 7-05, Minimum DesignLoads for Buildings and Other Structures. Although this standard adopts SEI/ASCE 7-02,it was being developed in parallel with SEI/ASCE 7-05. It is anticipated that ASCE willpublish a supplement to SEI/ASCE 7-05 in 2006 that will adopt ANSI/AISC 341 and 360by reference. We encourage anyone who is using these AISC standards to use them inconjunction with SEI/ASCE 7-05 including Supplement No. 1, when it becomes available.This allows these Provisions to be incorporated by reference into both the 2006 IBC and2006 NFPA 5000 building codes, each of which uses SEI/ASCE 7-05 as its basis for designloadings. Because the extent of changes that have been made to these Provisions, as a resultof incorporating both technical changes and the unified format is so large, they are beingrepublished in their entirety. The most significant modification is that two systems initiallydeveloped and incorporated into the 2003 NEHRP Provisions, the buckling-restrained bracedframe (BRBF) and the special plate shear wall (SPSW) have been added to the Provisions. Amajor update to the commentary is also provided.A number of other significant technical modifications are included, as follows: Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
6.1–iv PREFACE • Clarifying that the scope of structures covered includes “building-like nonbuilding structures.” • Clarifying that all steel buildings designed with an R factor greater than 3 must comply with the Provisions. • Adding new requirements to delineate the expectations for structural design drawings and specifications, shop drawings and erection drawings. • Adding new ASTM material specifications that are commonly used in the metal building industry. • Adding Rt values for all materials to be used in determining susceptibility of connections to fracture limit states. • Relaxing the limitations on use of oversized holes in bolted joints. • Defining a new term, “demand critical welds,” which have additional quality and toughness requirements. For each system, welds considered to be demand critical are defined. • Defining a new term, “protected zone,” to ensure that areas subject to significant inelastic deformations are not disturbed by other building construction operations. For each system, what areas are considered to be protected zones are defined. • Expanding the applicability of requirements on splices in columns that are part of the seismic load resisting system in moment frames to all systems. • Improving the provisions related to the design of column bases. • Making the stability bracing requirements more consistent throughout the document. • Added references to the new AISC Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (ANSI/AISC 358-05) as one means for SMF, IMF and EBF (link-to-column) connection acceptance. • Decreasing the column splice shear capacity requirements for SMF systems. • Increasing the stability bracing requirements for IMF systems. • Clarifying that connections meeting the requirements for SMF or IMF systems are also acceptable for OMF applications. • Increasing the requirements on SCBF systems that employ braces with high Kl/r ratios. • Reducing the connection force demand on OCBF bracing to allow the use of the amplified seismic load. • Eliminating the requirement to design all members in OCBF systems for the amplified seismic load, done for consistency with a corresponding reduction in the R factor for this system in SEI/ASCE 7-05 including Supplement 1. • Adding specific requirements for OCBF above seismic isolation systems. • Significantly improving the provisions related to quality assurance and quality control to address many of the issues identified in FEMA 353. • Making changes to Part II to be consistent with the modifications to Part I and changes to ACI 318. Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
PREFACE 6.1–vThe AISC Committee on Specifications, Task Committee 9—Seismic Provisions is responsiblefor the ongoing development of these Provisions. The AISC Committee on Specificationsgives final approval of the document through an ANSI-accredited balloting process, andhas enhanced these Provisions through careful scrutiny, discussion, and suggestions forimprovement. AISC further acknowledges the significant contributions of several groupsto the completion of this document: the Building Seismic Safety Council (BSSC), the SACJoint Venture, the Federal Emergency Management Agency (FEMA), the National ScienceFoundation (NSF), and the Structural Engineers Association of California (SEAOC).The reader is cautioned that professional judgment must be exercised when data orrecommendations in these provisions are applied, as described more fully in the disclaimernotice preceding the Preface.This specification was approved by the AISC Committee on Specifications:James M. Fisher, Chairman Tony C. HazelRoger E. Ferch, Vice Chairman Mark V. HollandHansraj G. Ashar Lawrence A. KloiberWilliam F. Baker Roberto T. LeonJohn M. Barsom Stanley D. LindseyWilliam D. Bast James O. MalleyReidar Bjorhovde Richard W. Marshall (deceased)Roger L. Brockenbrough Harry W. MartinGregory G. Deierlein David L. McKenzieDuane S. Ellifritt Duane K. MillerBruce R. Ellingwood Thomas M. MurrayMichael Engelhardt R. Shankar NairShu-Jin Fang Jack E. PetersenSteven J. Fenves Douglas A. Rees-EvansJohn W. Fisher Robert E. Shaw, Jr.Timothy P. Fraser Donald R. ShermanTheodore V. Galambos Lee ShoemakerLouis F. Geschwindner William A. ThorntonLawrence G. Griffis Raymond H. R. TideJohn L. Gross Cynthia J. Duncan, SecretaryThe Committee gratefully acknowledges the following task committee (TC 9—SeismicDesign) for their development of this document.James O. Malley, Chairman Roberto T. LeonMark C. Saunders, Vice Chairman Robert T. LyonsRoy Becker Sanjeev R. MalushteGregory G. Deierlein Harry W. MartinRichard M. Drake Clarkson W. PinkhamMichael D. Engelhardt Rafael SabelliRoger E. Ferch Thomas A. SabolTimothy P. Fraser Robert E. Shaw, Jr.Subhash C. Goel Kurt D. SwenssonJames R. Harris Cynthia J. Duncan, SecretaryPatrick M. Hassett Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
6.1–vi Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.