Structural Design in Wood

439 Pages·1989·19.494 MB·English

by  Judith J. Stalnaker Ph.D., P.E., Ernest C. Harris Ph.D., P.E. (auth.)

STRUCTURAL DESIGN IN WOOD
STRUCTURAL DESIGN IN WOOD
Judith J. Stalnaker, Ph.D., P.E.
University of Colorado at Denver
and
Ernest C. Harris, Ph.D., P.E.
University of Colorado at Denver
~ Springer Science+Business Media, LLC
Copyright © 1989 by Springer Science+B usiness Media New York
Originally published by Van Nostrand Reinhold in 1989
Softcover reprint of the hardcover I st edition 1989
Library of Congress Catalog Card Number 88-20842
ISBN 978-1-4684-9998-8 ISBN 978-1-4684-9996-4 (eBook)
DOI 10.1007/978-1-4684-9996-4
All rights reserved. No part of this work covered by the
copyright hereon may be reproduced or used in any form or
by any means-graphic, electronic, or mechanical, including
photocopying, recording, taping, or information storage and
retrieval systems-without written permission of the publisher.
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Library of Congress Cataloging-in-Publication Data
Stalnaker, Judith J.
Structural design in wood.
Includes index.
I. Building, Wooden. 2. Structural design.
I. Harris, Ernest C. II. Title.
TA666.S67 1989 624.1 '84 88-20842
ISBN 978-1-4684-9998-8
-- VNR STRUCTURAL ENGINEERING SERIES --
Structural Engineering Theory
STRUCTURES: FUNDAMENTAL THEORY AND BEHAVIOR by Richard Gutkowski
STRUCTURAL DYNAMICS. 2nd Ed .. by Mario P.az
MICROCOMPUTER-AIDED ENGINEERING: STRUCTURAL DYNAMICS by Mario
P.az
EARTHQUAKE RESISTANT BUILDING DESIGN AND CONSTRUCTION, 2nd Ed.,
by Norman Green
SEISMIC DESIGN FOR BUILDINGS HANDBOOK edited by Farzad Naeim
Steel Design
STEEL DESIGN FOR ENGINEERS AND ARCHITECTS by Rene Amon, Bruce
Knobloch and Atanu Mazumder
Concrete Design
HANDBOOK OF CONCRETE ENGINEERING by Mark Fintel
STRUCTURAL DESIGN GUIDE TO THE ACI BUILDING CODE, 3rd Ed., by P.aul F.
Rice, EdwardS. Hoffman, David P. Gustafson and Albert J. Gouwens
TORSION OF REINFORCED CONCRETE by T. Hsu
MODERN PRESTRESSED CONCRETE, 3rd Ed., by James R. Libby
Masonry
SIMPLIFIED MASONRY SKILLS by R. Kreh
Wood
MECHANICS OF WOOD AND WOOD COMPOSITES by Jozsef Bodig and
Benjamin Jayne
STRUCTURAL USE OF WOOD IN ADVERSE ENVIRONMENTS edited by Robert W.
Meyer and Robert M. Kellogg
STRUCTURAL DESIGN IN WOOD by Judith J. Stalnaker and Ernest C. Harris
Tall Buildings
DEVELOPMENTS IN TALL BUILDINGS by the Council on Tall Buildings
ADVANCES IN TALL BUILDINGS by the Council on Tall Buildings
SECOND CENTURY OF THE SKYSCRAPER by the Council on Tall Buildings
Other Structures-Related Books
ICE INTERACTION WITH OFFSHORE STRUCTURES by A.B. Cammaert and
D.B. Muggeridge
FOUNDATION ENGINEERING HANDBOOK by Hans Winterkorn and H. Y. Fang
FOUNDATION ENGINEERING FOR DIFFICULT SUBSOIL CONDITIONS by
Leonardo Zeevaert
ADVANCED DAM ENGINEERING edited by Robert Jansen
TUNNEL ENGINEERING HANDBOOK by John Bickel and T.R. Kuesel
SURVEYING HANDBOOK edited by Russell Brinker and Roy Minnick
Preface
Why another textbook on the design of wood sets this book apart is its inclusion of "struc
structures? In many years of teaching structural tural planning." Most textbooks show only the
design in wood, the authors have used virtually selection of member proportions or number of
every textbook available, as well as using only connectors in a joint to satisfy a given, com
a code and no textbook at all. The textbooks pletely defined situation. This book, on the
used have included both the old and the rela other hand, shows the thinking process needed
tively modem; some have been fairly good, but to determine whether or not the member is re
in our opinion each has deficiencies. Some quired in the first place. Following this, the
books have too few solved examples. Others spacing and continuity of the member are de
omit important material or have an arrange cided, its loads are determined, and finally its
ment making them difficult to use as formal shape and size are selected.
teaching tools. By writing this book, we intend We believe that illustrating structural plan
to correct such deficiencies. ning as well as detailed member and connec
The prime purpose of this book is to serve as tion design is of considerable value in helping
a classroom text for the engineering or archi the student make the transition from the often
tecture student. It will, however, also be useful simplistic classroom exercises to problems of
to designers who are already familiar with de the real world. Problems for solution by the
sign in other materials (steel, concrete, ma student follow the same idea. The first prob
sonry) but need to strengthen, refresh, or up lems in each subject are the usual textbook-type
date their capability to do structural design in problems, but in most chapters these are fol
wood. Design principles for various structural lowed by problems requiring the student to
materials are similar, but there are significant make structural planning decisions as well. The
differences. This book shows what they are. student may be required, given a load source,
The book has features that the authors be to find the magnitude of the applied loads and
lieve set it apart from other books on wood decide upon a grade of wood. Given a floor
structural design. One of these is an abundance plan, the student may be required to determine
of solved examples. Another is its treatment of a layout of structural members. The authors
loads. This book will show how actual member have used most of the problems in their classes,
loads are computed. The authors have found so the problems have been tested.
that students, more often than not, have diffi The book presents many of the design ex
culty recognizing how load is transferred from amples in the form of "computation sheets,"
one member to another-for example, how to solutions in the form of actual design office
proceed from a specified intensity of floor live computations. This is intended to reinforce the
load and type and thickness of floor material to instruction given in Chapter 1 regarding neat
knowing the actual load per unit length reach ness and orderliness in design computations.
ing the beam in question. Worked-out exam The book refers frequently to two codes-the
ples and student homework problems will il National Design Specification for Wood Con
lustrate the process. struction and the Uniform Building Code.
Another significant feature that we believe Wherever possible, however, the basic princi-
vii
viii PREFACE
pies behind code requirements are explained, been presented. They realize also that (I) be
and where the authors are aware of code short cause of its position in the course, connection
comings, that too is pointed out. We refer fre design is something most students learn about
quently to code requirements in the belief that almost as an afterthought (as though the subject
theory with no exposure to real life is not good is of lesser importance than the design of mem
education. What is needed is balance between bers); and (2) structural failures are far more
the theoretical and the practical (the latter is not frequent in the connections than in the mem
a bad word). bers themselves. Further, design of members
The authors have included an example of de can be done more effectively if the designer
signing for shear using "two-beam" action, so considers how the member will be connected,
that users of the book can better understand the before making a final selection of member size.
NDS provisions on the subject. However, the With these ~houghts in mind, the authors pre
authors do not recommend using "two-beam" sent the subject of connections before going on
action for design. to the design of structural members.
In general, the book assumes that the user Those who prefer to present the subject in
will be familiar with structural analysis. In fact, the conventional sequence can merely go on to
the authors intend that the book will reinforce Chapter 6, delaying the study of Chapter 5 until
the principles of structural analysis using wood after Chapter 8 (glulam design). It should work
as a vehicle. equally well with either sequence.
The authors use the book in a three semester In the authors' beginning three-hour course
hour beginning course and find that sufficient in timber structure design, Chapters 1 through
material remains that a second course could be 7, 9, 10, 11, most of 8, and parts of 12, 13,
taught from the same book. The prerequisite and 14 are included.
for the first course should be mechanics of ma The book is written to stand alone. Our
terials as a minimum, including the subjects of many instructors may find it beneficial to ask
shear and moment diagrams, flexural deflec their students to purchase the National Design
tions, and axial forces in truss members. A Specification for Wood Construction from the
more rigourous course in structural analysis, Publications Department of the National Forest
though desirable as a prerequisite, is not essen Products Association, 1250 Connecticut A venue
tial. N.W., Washington, D.C. 20036.
Chapter 5 (Connections-Nails, Screws, and
Bolts) is intentionally in an unconventional po JUDITH J. STALNAKER
sition. The authors realize that most books ERNEST C. HARRIS
cover connections after member design has Denver, Colorado
Contents
Preface I vii 3. Production and Grading of Sawn
Lumber I 33
1. Introduction I 1
3-1. Lumber Production I 33
1-1. Evolution of Timber Design I 1
3-2. Standard Sizes of Lumber I 33
1-2. Material Properties I 2
3-3. Finish Designations I 35
1-3. Types of Construction I 2
3-4. Cutting Patterns I 35
1-4. Hybrid Construction I 7
3-5. Drying I 37
1-5. Timber Bridges I 7
3-6. Lumber Grading 38
1-6. Notes to Students I 9
3-7. Types of Grading I 39
References I 10
3-8. Definitions I 40
3-9. Modem Grading Rules I 41
3-10. Example of Visual Grading of
2. Wood Structure and Properties I 11
Beams and Stringers I 41
2-1. Wood as a Structural 3-11. Grading Stamps I 42
Material I 11 3-12. Caution to Designer and
2-2. Problems in Use of Wood for Builder I 43
Structures I 11 3-13. Board Measure I 43
2-3. Advantages of Wood as a Example 3-1 I 44
Structural Material I 11 References I 44
2-4. Classification of Wood I 12 Problem I 44
2-5. Wood Structure I 14
2-6. Juvenile Wood I 17
4. Loads and Allowable Stresses I 45
2-7. Wood Axes I 18
2-8. Properties of Interest to the Part I. Loads I 45
Structural Designer I 18 4-1. General I 45
2-9. Factors Affecting Strength 21 4-2. Dead Loads I 46
2-10. Moisture Content I 21 Example 4-1 I 46
Example 2-1 I 22 Example 4-2 I 47
Example 2-2 I 23 Example 4-3 I 48
2-11. Specific Gravity I 23 4-3. Vertical Live Loads I 49
2-12. Time-Dependent Behavior of Example 4-4 I 50
Wood I 24 Example 4-5 I 52
2-13. Strength-Reducing Example 4-6 I 52
Characteristics I 26 Example 4-7 I 52
2-14. Thermal Properties of Example 4-8 I 52
Wood I 29 4-4. Wind Loads I 52
References I 30 4-5. Stability Under Wind
Problems I 31 Loads I 54
ix
x CONTENTS
4-6. Load Combinations I 55 References I 97
Example 4-9 I 55 Problems I 98
Example 4-10 I 57
6. Selecting Sawn-Timber Beams I 101
4-7. Seismic Loads I 57
Example 4-11 I 60 6-1. Introduction I 101
Part II. Allowable Stresses 60 6-2. Design for Flexure-Laterally
4-8. Allowable Stresses I 60 Supported Beams I 101
4-9. Establishing Basic Allowable Example 6-1 I 104
Stresses I 62 Example 6-2 I 104
4-10. Design Allowable Stresses I 64 Example 6-3 I 105
Example 4-12 I 66 Example 6-4 I 105
Example 4-13 I 67 Example 6-5 105
Example 4-14 I 67 6-3. Design for Flexure-Laterally
Example 4-15 I 67 Unsupported Beams I 106
Example 4-16 I 68 Example 6-6 I 108
Example 4-17 I 68 Example 6-7 I 109
Example 4-18 I 69 Example 6-8 I 109
4-11. Reliability-Based Design I 70 6-4. Design of Beams for
References I 71 Shear I 109
Problems I 71 Example 6-9 I 113
Example 6-10 I 113
Example 6-11 I 114
5. Connections-Nails, Screws, and
Example 6-12 I 114
Bolts I 74
Example 6-13 I 115
5-1. Connection Design I 74 Example 6-14 I 115
5-2. General Principles I 74 6-5. Deflection I 115
5-3. Nails and Spikes I 76 Example 6-15 I 118
Example 5-1 I 79 Example 6-16 I 118
Example 5-2 I 80 Example 6-17 I 118
Example 5-3 I 80 Example 6-18 I 119
Example 5-4 I 80 6-6. Design for Bearing I 119
Example 5-5 I 80 Example 6-19 I 121
Example 5-6 I 80 Example 6-20 I 121
5-4. Staples I 81 Example 6-21 I 121
5-5. Lag Screws I 81 6-7. Floor System Design I 121
Example 5-7 I 84 Example 6-22 I 122
Example 5-8 I 85 References I 125
Example 5-9 I 86 Problems I 125
5-6. Wood Screws I 87
7. Selecting Sawn-Timber Compression and
5-7. Bolted Connections I 87
Tension Members I 129
Example 5-10 I 92
Example 5-11 I 92 7-1. Wood Columns I 129
Example 5-12 I 93 7-2. Column Design I 131
Example 5-13 I 95 Example 7-1 I 134
Example 5-14 I 95 Example 7-2 I 135
Example 5-15 I 95 7-3. Round and Tapered
5-8. Bolts Loaded at an Angle to the Columns I 135
Bolt Axis I 96 Example 7-3 I 136
Example 5-16 I 97 Example 7-4 I 136
CONTENTS xi
7-4. Spaced Columns I 136 8-13. Three-Hinged Arches I 181
Example 7-5 I 139 Example 8-14 I 182
7-5. Built-Up Columns I 140 8-14. Glulam Columns I 183
Example 7-6 I 141 References I 184
7-6. Beam Columns I 141 Problems I 186
Example 7-7 I 143
Example 7-8 I 144 9. Bolts, Timber Connectors, and Special
Example 7-9 I 145 Weldments I 190
Example 7-10 I 145
9-1. Bolt Groups Subject to
7-7. Columns or Beam-Columns with
Moment I 190
Initial Curvature I 146
Example 9-1 I 191
7-8. Tension Members I 147
9-2. Connections with Moment-Bolts
Example 7-11 I 147
in Tension and Shear I 193
7-9. Combined Tension and Bending
Example 9-2 I 194
149
9-3. Stitch Bolts I 195
References I 149
9-4. Joist and Beam Hangers and
Problems I 150
Framing Anchors I 195
9-5. Special Weldments I 196
Example 9-3 I 199
8. Glued Laminated Members I 152
Example 9-4 I 201
8-1. Glulams I 152 Example 9-5 I 203
8-2. Advantages of Glulams over Sawn 9-6. Shear Plates and Split
Timbers I 153 Rings I 204
Example 8-1 I 154 9-7. Shear Plates I 205
8-3. Glulam Production I 155 9-8. Split Rings I 206
8-4. Standard Widths I 158 Example 9-6 I 206
8-5. Limits of Curvature I 159 Example 9-7 I 207
8-6. Allowable Stresses and Example 9-8 I 207
Modifications I 159 Example 9-9 I 208
Example 8-2 I 161 9-9. Spiked Grids and Grid
Example 8-3 I 162 Plates I 209
8-7. Suggested Design 9-10. Nailer Plates and Toothed
Procedure I 162 Plates I 210
Example 8-4 I 162 9-11. Drift Pins and Dowels I 210
Example 8-5 I 163 References I 211
Example 8-6 I 164 Problems I 211
8-8. Biaxial Bending I 165
10. Timber Trusses I 213
Example 8-7 I 165
8-9. Cantilever Beam Systems I 166 10-1. Wood Truss Types 213
Example 8-8 I 168 10-2. Light-Frame Trusses,
Example 8-9 I 168 Analysis I 216
Example 8-10 I 170 Example 10-1 I 219
8-10. Curved Glulams 170 10-3. Light-Frame Trusses, Member
Example 8-11 173 Design I 221
Example 8-12 174 10-4. Light-Frame Trusses, Connection
8-11. Tapered Glulams I 177 Design I 223
Example 8-13 I 180 Example 10-2 I 225
8-12. Members Both Tapered and 10-5. Bracing and Erection of Light
Curved I 181 Frame Trusses I 228