2012 IBC
®
SEAOC STRUCTURAL/SEISMIC DESIGN MANUAL
Volume 4
EXAMPLES FOR STEEL-FRAMED BUILDINGS
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Copyright Copyright © 2013 Structural Engineers Association of California. All rights reserved. This publication or any part thereof must not be reproduced in any form without the written permission of the Structural Engineers Association of California.
Publisher Structural Engineers Association of California (SEAOC) 1400 K Street, Ste. 212 Sacramento, California 95814 Telephone: (916) 447-1198; Fax: (916) 444-1501 E-mail:
[email protected]; Web address: www.seaoc.org The Structural Engineers Association of California (SEAOC) is a professional association of four regional member organizations (Southern California, Northern California, San Diego, and Central California). SEAOC represents the structural engineering community in California. This document is published in keeping with SEAOC’s stated mission: To advance the structural engineering profession; to provide the public with structures of dependable performance through the application of state-of-the-art structural engineering principles; to assist the public in obtaining professional structural engineering services; to promote natural hazard mitigation; to provide continuing education and encourage research; to provide structural engineers with the most current information and tools to improve their practice; and to maintain the honor and dignity of the profession. SEAOC Board oversight of this publication was provided by 2012 SEAOC Board President James Amundson, S.E. and Immediate Past President Doug Hohbach, S.E.
Editor International Code Council
Disclaimer While the information presented in this document is believed to be correct, neither SEAOC nor its member organizations, committees, writers, editors, or individuals who have contributed to this publication make any warranty, expressed or implied, or assume any legal liability or responsibility for the use, application of, and/or reference to opinions, findings, conclusions, or recommendations included in this publication. The material presented in this publication should not be used for any specific application without competent examination and verification of its accuracy, suitability, and applicability. Users of information from this publication assume all liability arising from such use. First Printing: August 2013
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Suggestions for Improvement Comments and suggestions for improvements are welcome and should be sent to the following: Structural Engineers Association of California (SEAOC) Don Schinske, Executive Director 1400 K Street, Suite 212 Sacramento, California 95814 Telephone: (916) 447-1198; Fax: (916) 444-1501 E-mail:
[email protected]
Errata Notification SEAOC has made a substantial effort to ensure that the information in this document is accurate. In the event that corrections or clarifications are needed, these will be posted on the SEAOC web site at www.seaoc.org and on the ICC web site at www.iccsafe.org. SEAOC, at its sole discretion, may issue written errata.
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Table of Contents Preface to the 2012 IBC SEAOC Structural/Seismic Design Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Preface to Volume 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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How to Use This Document. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix Design Example 1 Special Moment Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Design Example 2 Special Concentrically Braced Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Design Example 3 Buckling-Restrained Braced Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Design Example 4 Special Plate Shear Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Design Example 5 Eccentrically Braced Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Design Example 6 Multi-Panel OCBF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 Design Example 7 Metal Deck Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 a. Bare Metal Deck (Flexible) Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 b. Concrete-Filled Deck (Rigid) Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Design Example 8 Special Moment Frame Base Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Design Example 9 Braced-Frame Base Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 Appendix 1: General Building Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 2012 IBC SEAOC Structural/Seismic Design Manual, Vol. 4
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Preface to the 2012 IBC SEAOC Structural/Seismic Design Manual The IBC SEAOC Structural/Seismic Design Manual, throughout its many editions, has served the purpose of illustrating good seismic design and the correct application of building-code provisions. The manual has bridged the gap between the discursive treatment of topics in the SEAOC Blue Book (Recommended Lateral Force Requirements and Commentary) and real-world decisions that designers face in their practice. The examples illustrate code-compliant designs engineered to achieve good performance under severe seismic loading. In some cases simply complying with building-code requirements does not ensure good seismic response. This manual takes the approach of exceeding the minimum code requirements in such cases, with discussion of the reasons for doing so. Recent editions of the IBC SEAOC Structural/Seismic Design Manual have consisted of updates of previous editions, modified to address changes in the building code and referenced standards. Many of the adopted standards did not change between the 2006 edition of the International Building Code and the 2009 edition. The 2012 edition, which is the one used in this set of manuals, represents an extensive change of adopted standards, with many substantial changes in methodology. Additionally, this edition has been substantially revised. New examples have been included to address new code provisions and new systems, as well as to address areas in which the codes and standards provide insufficient guidance. Important examples such as the design of base-plate anchorages for steel systems and the design of diaphragms have been added. This expanded edition comprises five volumes: • • • • •
Volume 1: Code Application Examples Volume 2: Examples for Light-Frame, Tilt-Up, and Masonry Buildings Volume 3: Examples for Reinforced Concrete Buildings Volume 4: Examples for Steel-Framed Buildings Volume 5: Examples for Seismically Isolated Buildings and Buildings with Supplemental Damping
Previous editions have been three volumes. This expanded edition contains more types of systems for concrete buildings and steel buildings. These are no longer contained in the same volume. Volumes 3 and 4 of the 2012 edition replace Volume 3 of the 2009 edition. Additionally, we have fulfilled the long-standing goal of including examples addressing seismic isolation and supplemental damping. These examples are presented in the new Volume 5. In general, the provisions for developing the design base shear, distributing the base-shear-forces vertically and horizontally, checking for irregularities, etc., are illustrated in Volume 1. The other volumes contain more extensive design examples that address the requirements of the material standards (for example, ACI 318 and AISC 341) that are adopted by the IBC. Building design examples do not illustrate many of the items addressed in Volume 1 in order to permit the inclusion of less-redundant content. Each volume has been produced by a small group of authors under the direction of a manager. The managers have assembled reviewers to ensure coordination with other SEAOC work and publications, most notably the Blue Book, as well as numerical accuracy. This manual can serve as valuable tool for engineers seeking to design buildings for good seismic response. Rafael Sabelli Project Manager 2012 IBC SEAOC Structural/Seismic Design Manual, Vol. 4
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Preface to Volume 4 Volume 4 of the 2012 IBC SEAOC Structural/Seismic Design Manual addresses the design of steel building systems for seismic loading. Examples include the illustration of the design requirements for braced frames and moment frames, as were illustrated in previous editions, and also important interfaces with the rest of the structure. The design examples in this volume represent a range of steel structural systems. The Manual includes a set of examples that illustrate a more complete design: the design of diaphragms and collectors is illustrated, as are the design of base plates and anchorages for moment-frame and braced-frame columns. With the addition of these items this edition of the Manual offers more extensive guidance to engineers, addressing the design of these critical components of the seismic system. The design of each of these systems is governed by standards developed by the American Institute of Steel Construction (AISC). AISC produces its own Seismic Design Manual to illustrate the correct application of the AISC Seismic Provisions (AISC 341) and the AISC Prequalification Standard (AISC 358). The AISC Seismic Design Manual is a valuable resource for designers, and this volume is not intended to duplicate AISC’s efforts. This manual, for example, does not include the detailed range of options for gusset-plate design, as the AISC Seismic Design Manual addresses this design aspect thoroughly. Nevertheless, there is a fundamental difference in purpose and approach between this manual and the AISC Seismic Design Manual. The AISC Manual illustrates the code requirements, while the SEAOC Structural/ Seismic Design Manual illustrates SEAOC’s recommended practices, which traditionally have gone beyond the code (or in advance of it). The design examples for base plates are important examples of design methodologies not explicitly defined by building codes. Building code provisions for these connections are difficult to apply and do not correspond well to the mechanisms of resistance. The examples herein provide a convenient and valuable alternative methodology, one that is not an illustration of explicit code requirements. The methods illustrated herein represent approaches consistent with the ductility expectations for each system and with the desired seismic response. In most cases there are several details or mechanisms that can be utilized to achieve the ductility and resistance required, and the author of each example has selected an appropriate option. In many cases alternatives are discussed. This Manual is not intended to serve as a building code or to be an exhaustive catalogue of all valid approaches and details. The Manual is presented as a set of examples in which the engineer has considered the building-code requirements in conjunction with the optimal seismic response of the system. The examples follow the recommendations of the SEAOC Blue Book and other SEAOC recommendations. The examples are intended to aid conscientious designers in crafting designs that are likely to achieve good seismic performance consistent with expectations inherent in the requirements for the systems. Rafael Sabelli Volume 4 Manager
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Acknowledgements Volume 4 of the 2012 IBC SEAOC Structural/Seismic Design Manual was written by a group of highly qualified structural engineers, chosen for their knowledge and experience with structural engineering practice and seismic design. Kevin S. Moore, S.E., SECB, Principal, Simpson Gumpertz & Heger—Examples 1 and 8 With multiple state licenses, Kevin has more than 18 years of experience in structural engineering design, analysis, and evaluation. He is the Chair of the SEAOC Structural Standards Committee, Past Chair of the SEAOC Seismology Committee, and Chair of the Seismic Subcommittee of the NCSEA Code Advisory Committee. He has written multiple papers and design examples associated with steel design, seismic forces, and structural systems. Kevin is also a member of the AISC Connection Prequalification Review Panel. www.sgh.com Rafael Sabelli, S.E., Principal, Director of Seismic Design, Walter P. Moore—Volume 4 Manager and Example 2 Rafael Sabelli is a member of the AISC Task Committee on the Seismic Provisions for Structural Steel Buildings, Chair of the AISC Seismic Design Manual committee, a member of the ASCE 7 Seismic subcommittee, and a member of the BSSC Provisions Update Committee and Code Resource Support Committee. He is the coauthor (with Michel Bruneau) of AISC Design Guide 20: Steel Plate Shear Walls as well as of numerous research papers on conventional and buckling-restrained braced frames. He has served as Chair of the Seismology Committee of the Structural Engineers Association of California and as President of the Structural Engineers Association of Northern California. Rafael was the co-recipient of the 2008 AISC T.R. Higgins Lectureship and was the 2000 NEHRP Professional Fellow in Earthquake Hazard Reduction. Anindya Dutta, S.E., Ph.D, Simpson Gumpertz & Heger—Example 3 Dr. Dutta has over 12 years of experience in structural and earthquake engineering. He has provided analysis and design of a variety structures in high seismic zones. Dr. Dutta’s experience also includes seismic evaluation and strengthening of low-rise to high-rise structures. He has taught graduate and undergraduate level courses on concrete design and structural analysis at the State University of New York at Buffalo and is a regular lecturer at the San Francisco State University’s graduate program and at the University of California at Berkeley’s extension program. He has authored a number of technical reports and journal papers as well as served as a member of the review board for ASCE’s Structural Engineering Journal. Kenneth Tam, Simpson Gumpertz & Heger—Example 3 Kenneth has more than 17 years of experience in the field of structural and earthquake engineering. His experience includes structural design and evaluation of variety of structures in high seismic zones. He has co-authored various papers on design and analysis of buckling-restrained braced frames and has served on the ASCE41-13 Steel Subcommittee. Matthew R. Eatherton, Ph.D., S.E., Assistant Professor, Virginia Tech—Example 4 Matt has seven years of experience as a practicing structural engineer conducting high-seismic design in the San Francisco Bay Area. Now he serves on the faculty at Virginia Tech where he teaches classes on steel design, structural dynamics, and earthquake engineering. His research program includes both experimental and computational investigations of steel-plate shear walls, self-centering seismic systems, steel connections, and more. www.eatherton.cee.vt.edu
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Scott M. Adan, Ph.D., P.E., S.E., SECB, Principal, Adan Engineering—Example 5 With over 21 years of experience, Dr. Adan specializes in the investigation and design of buildings and structures. He is also actively involved in the research and development of steel moment-resisting connections. For the Structural Engineers Association of Northern California, he chairs the Steel Subcommittee. For the American Institute of Steel Construction, he is a member of the Seismic Design Manual Subcommittee, the Connection Prequalification Review Panel, and the Seismic Design Task Committee. www.adanengineering.com Anna Dix, S.E., Associate, Liftech Consultants Inc.—Example 6 Anna has eight years of practice in design and analysis of steel and concrete structures. Her focus is on special-use and marine structures including cranes, wharves, and heavy-lift and container-handling equipment. She has specialized experience with ductile tie-down systems for cranes, seismic design and analysis of steel structures, seismic crane-wharf interaction, designing ductile steel frames, and investigating fatigue cracking for various structures. In her spare time, Anna introduces engineering to inquisitive young minds. www.liftech.net Katy Briggs, S.E., Project Engineer, Thornton Tomasetti—Example 7 A licensed S.E. in the State of California, Katy Briggs has seven years of experience in structural analysis and design. She has worked on new buildings and seismic retrofits of existing buildings utilizing wood, steel, concrete, and masonry construction. These projects include education, healthcare, government, correctional, and commercial facilities. She has been involved with writing and editing design examples for steel diaphragms and special concentrically braced frames. Amit Kanvinde, Ph.D., Associate Professor of Civil and Environmental Engineering, University of California, Davis—Example 8 Amit’s research heavily focuses on the seismic response of steel structures and connections through experimentation and simulation. Pertinent to the design example, he has conducted 28 large-scale tests on column base connections and is the author of two major technical reports and several journal and conference papers on the topic of base plates. His other recent research has addressed the fracture of seismic column splices in moment frames and braces in SCBF systems. He is the recipient of the 2008 ASCE Norman Medal and the 2003 EERI Graduate Student Paper award addressing the collapse of structures. David A. Grilli, M.S., E.I.T., Graduate Student Researcher, University of California, Davis— Example 8 David is a doctoral student in the Department of Civil and Environmental Engineering at UC Davis. Through large-scale experimentation, his work addresses the seismic response of embedded and exposed column-base plates. Pertinent to this example, he is co-author of a journal article that characterizes the rotational flexibility of exposed column base connections. David was the recipient of the AISC Structural Steel Education Council scholarship in 2009, and the Farrer/Patten Award for outstanding student in Civil Engineering at UC Davis in 2012. Lindsey Maclise, Associate, Forell/Elsesser Engineers Inc.—Example 9 Lindsey is currently an Associate with Forell/Elsesser Engineers specializing in seismic design for both new construction and retrofit. She received her B.S. and M.S. from the University of California, Berkeley and is an active member of SEAONC, SEI, and EERI. She is currently serving as a Housner Fellow for her work in Sustainable Seismic Design. www.forell.com
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Additionally, a number of SEAOC members and other structural engineers helped check the examples in this volume. During its development, drafts of the examples were sent to these individuals. Their help was sought in review of code interpretations as well as detailed checking of the numerical computations. The reviewers include: Geoff Bomba Mike Cochran Andrew Cussen Tom Hale Walterio López Sara Jozefiak Ryan Kersting Benjamin Mohr Carrie Leung Thomas Nunziata Patxi Uriz Laura Whitehurst Close collaboration with the SEAOC Seismology Committee was maintained during the development of the document. The Seismology Committee has reviewed the document and provided many helpful comments and suggestions. Their assistance is gratefully acknowledged. Production and art was provided by the International Code Council.
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References Standards American Concrete Institute. ACI 318: Building Code Regulations for Reinforced Concrete, Farmington Hills, Michigan, 2011. American Institute of Steel Construction. AISC 341: Seismic Provisions for Structural Steel Buildings, Chicago, Illinois, 2010. American Institute of Steel Construction. AISC 358: Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications, Chicago, Illinois, 2010. American Institute of Steel Construction. AISC 360: Specification for Structural Steel Buildings, Chicago, Illinois, 2010. American Society of Civil Engineers. ASCE 7: Minimum Design Loads for Buildings and Other Structures. ASCE 2010. International Code Council. International Building Code (IBC). Falls Church, Virginia, 2012.
Other References American Institute of Steel Construction. Manual of Steel Construction, Chicago, Illinois, 2012. American Institute of Steel Construction. Seismic Design Manual, Chicago, Illinois, 2013. Anonymous, 1977. “Shear walls and slipforming speed Dallas’ Reunion project” Engineering News Record, 20–21, July 28. Anonymous, 1978a. “Patent problems, challenge spawn steel seismic walls” Engineering News Record, 17, January 26. Anonymous, 1978b. “Quake-proof hospital has battleship-like walls” Engineering News Record, 62–63, Sept. 21. Astaneh-Asl, A. 2005. “Design of Shear Tab Connections for Gravity and Seismic Loads,” Steel Technical Information and Product Report. Structural Steel Educational Council, CA. Basler, K. 1961. “Strength of Plate Girders in Shear” Journal of the Structural Division, ASCE, Vol. 87, No. ST7 October. Berman, J. W. and Bruneau, M. 2004. “Steel Plate Shear Walls are Not Plate Girders” AISC Engineering Journal, Third Quarter. Berman, J. W. and Bruneau, M. 2008. “Capacity Design of Vertical Boundary Elements in Steel Plate Shear Walls” AISC Engineering Journal, First Quarter.
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Bozorgnia, Y., Bertero, V., 2004. Earthquake Engineering: From Engineering Seismology to Performance-Based Engineering. CRC Press, LLC, Danvers, Massachusetts. Bruneau, M., Uang, C.M., and Sabelli, R. Ductile Design of Steel Structures. McGraw-Hill, 2011. CAN/CSA S16-09 2009. “Limit States Design of Steel Structures,” published by Canadian Standards Association. Cheng, J.J.R., and Kulak, G.L. 2000. Gusset plate connection to round HSS tension members. Engineering Journal, AISC, 4th Quarter, 133–139. Clifton, C., Bruneau, M., MacRae, G., Leon, R., Russell, A., 2011. “Steel Structures Damage from the Christchurch Earthquake of February 22, 2011,” NZST, Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 44, No. 4. DeWolf, J. T., and Ricker, D. T. 1990. AISC Design Guide 1—Column Base Plates, Published by the American Institute of Steel Construction, AISC. Engelhardt, M., and Popov, E., 1989. “On Design of Eccentrically Braced Frames,” Earthquake Spectra, EERI, Vol. 5, No. 3, 495–511. Englehardt, M. Personal correspondence and notes. 2012. Fisher, J.M. and Kloiber, L.A. 2006. “Base Plate and Anchor Rod Design,” 2nd Ed., Steel Design Guide Series No. 1, American Institute of Steel Construction, Inc., Chicago, IL. Gomez, I.R., Kanvinde A.M., and Deierlein G.G. 2010. “Exposed Column Base Connections Subjected to Axial Compression and Flexure,” Report Submitted to the American Institute of Steel Construction (AISC), Chicago, IL. Gomez, I.R., Kanvinde, A.M., and Deierlein, G.G. 2011. “Experimental investigation of shear transfer in exposed column base connections,” Engineering Journal, American Institute of Steel Construction, 4th Quarter, 246–264. ICC/SEAOC 2006. “Design Example 4—Steel Plate Shear Walls”, 2006 IBC Structural/Seismic Design Manual, Volume 3, Structural Engineers Association of California, Sacramento, California. Imanpour, A., Tremblay, R., and Davaran, A. “Seismic Evaluation of Multi-Panel Steel Concentrically Braced Frames,” 15th World Conference on Earthquake Engineering, 2012. Lehman, D., Roeder, C. 2, Johnston, S. 1, Herman D. 1, and Kotulka, B. 1 2008 “Improved Seismic Performance of Gusset Plate Connections”, ASCE Journal of Structural Engineering, Vol. 134, No. 6, 181–189. Luttrell, Larry D. 1967. “Strength and behavior of light-gage steel shear diaphragms”, Cornell Research Bulletin 67-1, sponsored by the American Iron and Steel Institute, Ithaca, NY. Moehle, Jack P., Hooper, John D., Kelly, Dominic J., and Meyer, Thomas. 2010. “Seismic design of cast-in-place concrete diaphragms, chords, and collectors: A guide for practicing engineers,” NEHRP Seismic Design Technical Brief Number 3, produced by the NEHRP Consultants Joint Venture, a partnership of the Applied Technology Council and the Consortium of Universities xvi
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for Research in Earthquake Engineering, for the National Institute of Standards and Technology, Gaithersburg, MD, NIST GCR 10-917-4. Moore, Kevin S., Feng, Joyce Y., June 2007. “Design of RBS Connections for Special Moment Frames,” Steel Tips. Structural Steel Educational Council, Moraga, California. Myers, A.T., Kanvinde, A.M., Deierlein, G.G., and Fell B.V. 2009, “Effect of Weld Details on the Ductility of Steel Column Baseplate Connections,” Journal of Constructional Steel Research, Volume 65, Issue 6, June 2009, 1366–1373. Porter, D.M., Rockey, K.C. and Evans, H.R. 1975. “The collapse behavior of plate girders loaded in shear”, The Structural Engineer, London England, Vol. 53, No. 8., Aug. Prasad, Badri K., Thompson, Douglas S., and Sabelli, Rafael. 2009. Guide to the design of diaphragms, chords and collectors based on the 2006 IBC and ASCE/SEI 7-05, International Code Council Publications, Country Club Hills, IL. Purba, R. and Bruneau, M. 2009. “Finite-Element Investigation and Design Recommendations for Perforated Steel Plate Shear Walls” Journal of Structural Engineering, Vol. 135, No. 11, 1367–1376. Purba, R., and Bruneau, M. 2007. Design Recommendations for Perforated Steel Plate Shear Walls Technical Report MCEER-07-0011. Qu, B., and Bruneau, M. 2010. “Capacity Design of Intermediate Horizontal Boundary Elements of Steel Plate Shear Walls” Journal of Structural Engineering, Vol. 136, No. 6. Ricles, J., and Popov, E., 1989, “Composite Action in Eccentrically Braced Frames,” Journal of Structural Engineering, ASCE, Vol. 115, No. 8, 2046–2065. Roberts, T. M. and Sabouri-Ghomi, S. 1991. “Hysteretic Characteristics of Unstiffened Plate Shear Panels” Thin-Walled Structures, Elsevier Science Publishers, Great Britain, 1991. Rogers, C.A. and Tremblay, R. 2008. “Impact of Diaphragm Behavior on the Seismic Design of Low-Rise Steel Buildings”, AISC Engineering Journal, First Quarter. Sabelli, R. and Bruneau, M. 2006. AISC Design Guide 20—Steel Plate Shear Walls, Published by the American Institute of Steel Construction, AISC. Sabelli, Rafael, Sabol, Thomas A., and Easterling, Samuel W. 2011. “Seismic design of composite steel deck and concrete-filled diaphragms: A guide for practicing engineers,” NEHRP Seismic Design Technical Brief Number 5, produced by the NEHRP Consultants Joint Venture, a partnership of the Applied Technology Council and the Consortium of Universities for Research in Earthquake Engineering, for the National Institute of Standards and Technology, Gaithersburg, MD, NIST GCR 10-917-10. Schumacher, A., Grondin, G.Y. and Kulak, G.L. 1999. “Connection of Infill Panels in Steel Plate Shear Walls” Canadian Journal of Civil Engineering, Vol. 26. SDI 2004. Diaphragm design manual, Third Edition (SDI DDMO3), Steel Deck Institute, Fox Grove, IL.
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SEAOC Blue Book, Recommended Lateral Force Requirements and Commentary. Structural Engineers Association of California, Sacramento, California. SEAOC Seismology Committee 2007. “Development of System Factors,” May 2007, The SEAOC Blue Book: Seismic design Recommendations, Structural Engineers Association of California, Sacramento, CA. SEAOC Seismology Committee 2008. “Concentrically Braced Frames,” August, 2008, The SEAOC Blue Book: Seismic Design Recommendations, Structural Engineers Association of California, Sacramento, CA. Accessible via the world wide web at: http://www.seaoc.org/bluebook/index. html SEAOC Seismology Committee, FEMA 350 Task Group, 2002. “Commentary and Recommendations on FEMA 350—Appendix D,” Structural Engineers Association of California, Sacramento, CA. Stoakes, C.D., Fahnestock, L.A. “Influence of Weak-axis Flexural Yielding on Strong-axis Buckling Strength of Wide Flange Columns,” Proceedings of the Annual Stability Conference, Structural Stability Research Council, April 2012. Structural Engineers Association of California (SEAOC) Seismology Committee, 2008. SEAOC blue book: Seismic design recommendations, Structural Engineers Association of California, Sacramento, CA. Thornton, W.A., and Fortney, P. 2012, “Satisfying Inelastic Rotation Requirements for In-plane Critical Axis Brace Buckling for High Seismic Design.” Engineering Journal, AISC, Vol. 49, No. 3, 3rd Quarter. Tremblay, R. 2001, “Seismic Behavior and Design of Concentrically Braced Steel Frames,” Engineering Journal, AISC, Vol. 38, No. 3, Chicago, IL. Tremblay, R., Archambault, M.-H., Filiatrault, A. “Seismic Response of Concentrically Braced Steel Frames Made with Rectangular Hollow Bracing Members,” December, 2003, Article 2003. 129:1626–1636, Journal of Structural Engineering, American Society of Civil Engineers. Tremblay, R., et al. “Seismic Design of Steel Structures in Accordance with CSA-S16-09,” July 25– 29, 2010, Paper No. 1768, Proceedings of the 9th US National and 10th Canadian Conference on Earthquake Engineering, Toronto, Ontario, Canada. Vian, D., and Bruneau, M. 2005. “Steel Plate Shear Walls for Seismic Design and Retrofit of Building Structures” Technical Report MCEER 05-0010. Vian, D., Bruneau, M., Tsai, K.C., and Lin, Y.-C. 2009. “Special Perforated Steel Plate Shear Walls with Reduced Beam Section Anchor Beams 1: Experimental Investigation” Journal of Structural Engineering, Vol. 135, No. 3, 211–220. Wong, Alfred F. “Multi-tier Bracing Panels within a Storey,” Advantage Steel, Canadian Institute of Steel Construction, No. 43, Summer 2012. Zayas, V., Mahin, S., Popov, E. “Cyclic Inelastic Behavior of Steel Offshore Structures,” August 1980, Report No. UCB/EERC-80/27 to the American Petroleum Institute, Earthquake Engineering Research Center & College of Engineering at University of California, Berkeley. xviii
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How to Use This Document Equation numbers in the right-hand margin refer to the one of the standards (e.g., AISC 341, AISC 358, AISC 360, ASCE 7). The default standard is given in the heading of each section of each example; equation numbers in that section refer to that standard unless another standard is explicitly cited. Abbreviations used in the “Code Reference” column are § – Section
T – Table
F – Figure
Eq – Equation
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Design Example 1 Special Moment Frame
OVERVIEW Structural steel special moment frames (SMF) are typically comprised of wide-flange beams, columns, and beam-column connections. Connections are proportioned and detailed to resist internal forces (flexural, axial, and shear) that result from imposed displacement as a result of wind or earthquake ground shaking. Inelasticity and energy dissipation are achieved through localized yielding of the beam element outside of the beam-column connection. Special proportioning and detailing of this connection is essential to achieving the desired inelastic behavior. The anticipated seismic behavior of the SMF system is long-period, high-displacement motion, with well distributed inelastic demand shared by all participating beam-column connections. System yielding mechanisms are generally limited to frame beams with the intent to invoke yielding at the base of frame columns. In many cases, engineers may model a SMF system with pin-based columns as significant stiffness is required to yield the base of large wide-flange members. If yielding at the base of the frame is desired to occur within the column section, the column might be extended below grade and tied into a basement wall or a ground-level beam, which is added to create a beam-column connection. Economies of construction usually limit the size of beam and column elements based on imposed displacement/drift limits. Design regulations for steel SMF are promulgated in a series of standards: ASCE/SEI 7, ANSI/AISC 341, ANSI/AISC 358, and ANSI/AISC 360. AISC 358 provides specific regulations related to prequalification of certain SMF connection types that obviate project-specific testing required by AISC 341. This design example follows the provisions of AISC 358 for the RBS connection type for the steel SMF seismic-forceresisting system. The six-story steel office structure depicted in the figure above has a lateral-force-resisting system comprising structural steel special moment frames. The typical floor framing plan is shown in Figure 1–1. A typical frame elevation is depicted in Figure 1–2. This design example utilizes simplifying assumptions 2012 IBC SEAOC Structural/Seismic Design Manual, Vol. 4
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Design Example 1
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Special Moment Frame
for ease of calculation or computational efficiency. Because bay sizes vary, the example frames can be designed with different participating bays in each direction, which will result in different sizes of beams and columns for each frame depending on location. This example explores the design of a single frame and a single connection of that frame. Assumptions related to base-of-column rotational restraint (assumed fixed), applied forces (taken from the base example assumptions), and applied wind force (not considered) are all incorporated into the example in “silent” consideration. Beam and column element sizes were determined using a linear elastic computer model of the building. These element sizes were determined through iteration such that code-required drift limits, element characteristics, and strength requirements were met. While this example is accurate and appropriate for the design of steel SMF structures, different methodologies for analysis, connection design, and inelastic behavior can be utilized, including the use of proprietary SMF connection design. This example does not explore every possible option, nor is it intended to be integrated with other examples in this document (i.e. Base Plate Design, Passive Energy Dissipation).
OUTLINE 1. Building Geometry and Loads 2. Calculation of the Design Base Shear and Load Combinations 3. Vertical and Horizontal Distribution of Load 4. SMF Frame 5. Element and RBS Connection Design 6. Detailing of RBS Connection
1. Building Geometry and Loads 1.1 GIVEN INFORMATION • Per Appendix A 䡩
Office occupancy on all floors
䡩
Located in San Francisco, CA, at the latitude and longitude given
䡩
Site Class D
䡩
120 feet × 150 feet in plan with typical floor framing shown in Figure 1–1
䡩
Frame beam and column sizes for lines 1 and 5 (Figure 1–2) 䡲
䡩
Beam and column sizes will vary from those on lines A and F
Six-stories as shown in Figure 1–2
• Structural materials
2
䡩
Wide-flange shapes
䡩
Pates
䡩
Weld electrodes
ASTM A992 (Fy = 50 ksi) ASTM A572, Grade 50 E70X-XX
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Design Example 1
A
B
C
E
D
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Special Moment Frame
F
5 @ 30' – 0'' = 150' – 0'' 5
4
3
2
1
Figure 1–1. Typical floor framing plan
A
B
E
D
C
F
TOP OF PARAPET
ROOF
W21 X 150
W30 X 99
W30 X 99
W30 X 99
W21 X 150
6th FLR
W21 X 150
W30 X 116
W30 X 116
W30 X 116
W21 X 150
5th FLR
W21 X 150
W30 X 132
W30 X 132
W30 X 132
W21 X 150
4th FLR
W21 X 150
W30 X 148
W30 X 148
W30 X 148
W21 X 150
3rd FLR
W21 X 150
W30 X 173
W30 X 173
W30 X 173
W21 X 150
2nd FLR
W21 X 150
W30 X 191
W30 X 191
W30 X 191
W21 X 150
1st FLR Figure 1–2. Frame elevation – line 1 (line 2 in background) 2012 IBC SEAOC Structural/Seismic Design Manual, Vol. 4
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Design Example 1
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Special Moment Frame
1.2 FLOOR WEIGHTS For development of seismic forces per Appendix A:
Table 1–1. Development of seismic forces per Appendix A
Level
Unit Wt (psf)
Area (ft2)
Weight (kips)
Floor
78
15,220
1187
Ext Wall
19
6990
133
Roof
36
15,220
548
Ext Wall/Parapet
19
5700
108
Assembly
Typical floor
Floor Wt (kips) 1315
Roof
656
W = 5(1320 kips) + 656 kips = 7256 kips
2. Calculation of the Design Base Shear and Load Combinations
ASCE 7
2.1 CLASSIFY THE STRUCTURAL SYSTEM AND DETERMINE SPECTRAL ACCELERATIONS Per ASCE 7 Table 12.2–1 for special steel moment frame: R = 8.0
Ωo = 3
Cd = 5.5
2.2 DESIGN SPECTRAL ACCELERATIONS The spectral accelerations to be used in design are derived in Appendix A: SDS = 1.00g
SD1 = 0.60g
2.3 DESIGN RESPONSE SPECTRUM Determine the approximate fundamental building period, Ta, using Section 12.8.2.1: Ct = 0.028 and x = 0.8 Ta
Ct hnx = 0.028 028 × 720 8 = 0 86 sec
T 12.8–2 (see discussion below)
Eq 12.8–7
Ta = 0.86 sec To = 0 2
4
S D1 0 60 =02 = 0 12 sec S DS 1 00
§11.4.5
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Design Example 1
Sa
⎛ T⎞ S DS 0 4 + 0 6 ⎟ = 0 4 + 5 0T T ⎝ o⎠
TS =
S D1 0 60 = = 0 60 sec S DS 1 00
Sa =
S D1 0 60 = T T
䡲
For T < To
Special Moment Frame
Eq 11.4–5 §11.4.5
For T > Ts.
Eq 11.4–6
The long-period equation for Sa does not apply here because the long-period transition occurs at 12 sec (from ASCE 7 Figure 22–12).
Design Spectral Acceleration, Sa (g)
1.2
TS = 0.60 sec SDS = 1.0g
1 0.8
SMF Building Period Ta= 0.86 sec, Sa= 0.70g
To= 0.12 sec
0.6
Tmax= 1.20 sec, Sa= 0.50g
Sa= 0.4+5.0T
0.4 Sa= 0.60/T
0.2 0 0
0.5
1
1.5
2
Period (Sec) Figure 1–3. Design Response Spectrum for the example building
Figure 1–3 depicts the design spectral acceleration determined from T, which is greater than TS , so the design spectral acceleration Sa is 0.70g. ASCE 7 Section 12.8.2 indicates that the fundamental period of the structure “can be established using the structural properties and deformational characteristics of the resisting elements in a properly substantiated analysis,” which might allow a linear elastic modal analysis to suffice. Section 12.8.2, however, limits the period that can be used to calculate spectral acceleration to a value of Tmax = Cu × Ta , where Cu is a factor found in Table 12.8–1. In this case Tmax = 1.4 × 0.86 = 1.20 sec. For preliminary design, the approximate period, Ta , will be used to design the SMF. As SMF designs are heavily dependent on meeting drift requirements, the initial value (usually found to be much lower than the period found through mathematical modeling) will suffice for the first design iteration. 2012 IBC SEAOC Structural/Seismic Design Manual, Vol. 4
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