StaggeredTrussFramingSystems
Neil Wexler PEWexlerAssociatesConsultingEngineersNew York NY
Feng-Bao Lin PhD PEPolytechnic UniversityBrooklyn NY
Copyright @ 2001
by
American Institute of Steel Construction Inc.
All rights reserved.This book or any part thereofmust not be reproduced in any form without thewritten permission of the publisher.
The information presented in this publication has been prepared in accordance with rec-be accurate this information should not be used or relied upon for any specific appli-cation without petent professional examination and verification of its accuracy. suitablility and applicability by a licensed professional engineer designer or architect.The publication of the material contained herein is not intended as a representationor of freedom from infringement of any patent or patents. Anyone making use of this information assumes alliability arising from such use.
Caution must be exercised when relying upon other specifications and codes developed
by other bodies and incorporated by reference herein since such material may be mod-ified or amended from time to time subsequent to the printing of this edition. The Institute bears no responsibility for such material other than to refer to it and incorporateit by reference at the time of the initial publication of this edition.
Printed in the United States of AmericaFirst Printing: December 2001Second Printing: December 2002
AUTHORS
PREFACE
East 47h Street New York NY 10017-2129 Tel: Neil Wexler PE is the president of Wexler Associates 225212.486.7355. He has a Bachelor's degree in Civil Engi- neering from McGil University (1979) a Master’s degreeand he is a PhD candidate with Polytechnic University. in Engineering from City University of New York (1984);:New York NY. He has designed more then 1 000 buildingstructures.
In recent years staggered truss steel framing has seen anationwide renaissance. The system which was developed at MIT in the 1960s under the sponsorship of the U.S. SteelCorporation has many advantages over conventional fram-ing and when designed in bination with precast con- crete plank or similar floors it results in a floor-to-floorheight approximately equal to flat plate construction.
Between 1997 and 2000 the authors had the privilege todesign six separate staggered tuss building projects. Whileresearching the topic the authors realized that there was lit- tle or no written material available on the subject. Simulta-recognized the benefits of staggered trusses over other sys- neously the AISC Task Force on Shallow Floor Systemsdesign guide. This design guide thus summarizes the tems and generously sponsored the development of thisresearch work and the practical experience gathered.
mally one-story deep and located in the demising walls Generally in staggered-truss buildings trusses are nor-between rooms with a Vierendeel panel at the corridors.the field to the columns. Spandrel girders are bolted to the The trusses are prefabricated in the shop and then bolted inrior walls are supported on the spandrel girders as in con- columns and field welded to the concrete plank. The exte-ventional framing.
Feng-Bao Lin PhD PE is a professor of Civil Engineer- ing of Polytechnic University and a consultant with WexlerAssociates. He has a Bachelor’s degree in Civil Engineer- ing from National Taiwan University (1976) Master'sdegree in Structural Engineering (1982) and PhD in Struc-tural Mechanics from Northwestem University (1987).
Staggered trusses provide excellent lateral bracing. Formid-rise buildings there is litle material increase in stag- gered trusses for resisting lateral loads because the trussessss Susisa peo leae[ jo ed se uoa ia aapplication for residential facilities. as mou pue Suoxa ue uasandau sassnn passses sm
have building design experience. It is remended that the This design guide is written for structural engineers whoreaders bee familiar with the material content of the ref-structural design. The design guide is written to help the erences listed in this design guide prior to attempting a firstdesigner calculate the initial member loads and to perform approximate hand calculations which is a requisite for theselection of first member sizes and the final puter analyses and verification.
Chapter 7 on Fire Resistance was written by Esther Slub-ski and Jonathan Stark from the firm of Perkins Eastman Architects. Section 5.1 on Seismic Strength and DuctilityRequirements was written by Robert McNamara from the firm of McNamara Salvia Inc. Consulting StructuralEngineers.
ACKNOWLEDGEMENTS
Staggered Truss Design Guide Review Group for their The authors would like to thank the members of the AISCreview mentary and assistance in the development ofthis design guide:
J. Steven AngellMichael L. Baltay Aine M. BrazilCharles J. Carter Thomas A. FaraoneRichard A. Henige Jr.Stanley D. Lindsey Socrates A. IoannidesRobert W. Pyle Robert J. McNamaraKurt D. Swensson
Their ments and suggestions have enriched thisdesign guide. Special thanks go to Robert McNamara from
Section 5.1 Strength and Ductility Design Requirements. McNamara Salvia Inc. Consulting Engineers who wroteBob's extensive experience and knowledge of structuralto Esther Slubski who wrote Chapter 7 on Fireproofing. design and analysis techniques was invaluable. Also thanks
Special thanks also go to Marc Gross from the firm ofBrennan Beer Gorman Architects Oliver Wilhelm from Cybul & Cybul Architects Jonathan Stark from PerkinsEastman Architects Ken Hiller from Bovis Inc. Allan Paull of Tishman Construction Corporation of New York Larry Danza and John Kozzi of John Maltese Iron Works Inc. who participated in a symposium held in New York on special topics for staggered-truss building structures.
Angell Thomas Faraone and Robert Pyle of the American Last but not least the authors thank Charlie Carter SteveInstitute of Steel Construction Inc. who have coordinated scheduled and facilitated the development of this designguide.
Chapter 1
Chapter 2
Chapter 3
Chapter 4
TableofContents
Authors ..Preface Acknowledgements vi
1.1 Advantages of Staggered Trusses. 1.2 Material Description.1.3 I 1.4 Responsibilities Framing Layout 2 31.5 Design Methodology 1.6 Design Presentation 44
Diaphragm Action with Hollow Core Slabs.
2.1 General Information. 72.2 Transverse Shear in Diaphragm . Distribution of Lateral Forces 72.4 Diaphragm Chords 2.3 10 9
3.1 Hand and Computer Calculations 3.2 Live Load Reduction . 153.30 Gravity Loads. 15 153.4Lateral Loads 3.5 Load Coefficients. 17 173.6 Vertical and Diagonal Members. 193.8 3.7 Computer Modeling - Truss Chords. 193.9 Columns 21
Conneetions in Staggered Trusses. 25
4.2 4.1 Connection Between Web Member General Information. 254.3 Connection Between Gusset Plate and Gusset Plate 25 274.5 Miscellaneous Considerations - 4.4 Design Example 27 27
Chapter 6
Chapter 7
5.1 Strength and Ductility Design5.2 New Seismic Design Considerations Requirements 295.3 Ductility of Truss Members . for Precast Concrete Diaphragms. 29 295.5 New Developments in Gusset Plate 5.4 Seismic Design of Gusset Platesto HSS Connections 31
6.1 Openings. Mechanical Design Considerations .. 336.3 Plank Leveling 6.2 33 336.4 Erection Considerations . 6.5 Coordination of Subcontractors 33 346.6 Foundation Overturning and Sliding 346.8Balconies 6.7 Special Conditions of Symmetry . 35 356.9 Spandrel Beams 35
Fire Protection of Staggered Trusses 37
References 39
