Wood Handbook- Wood as an Engineering Material.pdf

Abstract

Summarizes information on wood as an engineering material.

Presents properties of wood and wood-based products of

particular concern to the architect and engineer. Includes

discussion of designing with wood and wood-based products

along with some pertinent uses.

Keywords: wood structure, physical properties (wood),

mechanical properties (wood), lumber, wood-based

composites, plywood, panel products, design, fastenings,

wood moisture, drying, gluing, fire resistance, finishing,

decay, sandwich construction, preservation, and wood-

based products

On the cover : (Left to right, top to bottom)

1. Research at the Forest Products Laboratory,

Madison, Wisconsin, contributes to maximizing

benefits of the Nation’s timber resource.

2. Testing the behavior of wood in fire helps

enhance fire safety.

3. The all-wood, 162-m (530-ft ) clear-span Tacoma

Dome exemplifies the structural and esthetic

potential of wood construction (photo courtesy of

Western Wood Structures, Inc., Tualatin,

Oregon).

4. Bending tests are commonly used to determine

the engineering properties of wood.

5. Engineered wood trusses exemplify research

that has led to more efficient use of wood.

6. The Teal River stress-laminated deck bridge is

located in Sawyer County, Wisconsin.

7. Kiln drying of wood is an important procedure

during lumber manufacturing.

8. Legging adhesive (photo courtesy of Air Products

and Chemicals, Inc., Allentown Pennsylvania).

Adhesive bonding is a critical component in the

performance of many wood products.

March 1999

Forest Products Laboratory. 1999. Wood handbook—Wood as an

engineering material. Gen. Tech. Rep. FPL–GTR–113. Madison, WI:

U.S. Department of Agriculture, Forest Service, Forest Products

Laboratory. 463 p.

A limited number of free copies of this publication are available to the

public from the Forest Products Laboratory, One Gifford Pinchot Drive,

Madison, WI 53705–2398. Laboratory publications are sent to hundreds

of libraries in the United States and elsewhere. This publication may

also be viewed on the FPL website at www.fpl.fs.fed.us/.

The Forest Products Laboratory is maintained in cooperation with the

University of Wisconsin.

The use of trade or firm names is for information only and does not imply

endorsement by the U.S. Department of Agriculture of any product or

service.

The United States Department of Agriculture (USDA) prohibits discrimi-

nation in all its programs and activities on the basis of race, color, national

origin, gender, religion, age, disability, political beliefs, sexual orientation,

or marital or familial status. (Not all prohibited bases apply to all pro-

grams.) Persons with disabilities who require alternative means for com-

munication of program information (braille, large print, audiotape, etc.)

should contact the USDA’s TARGET Center at (202) 720–2600 (voice and

TDD). To file a complaint of discrimination, write USDA, Director, Office

of Civil Rights, Room 326-W, Whitten Building, 14th and Independence

Avenue, SW, Washington, DC 20250–9410, or call (202) 720–5964

(voice and TDD). USDA is an equal employment opportunity employer.

Pesticide Precautionary Statement

This publication reports research involving pesticides.

It does not contain recommendations for their use, nor

does it imply that the uses discussed here have been

registered. All uses of pesticides must be registered by

appropriate State and/or Federal agencies before they

can be recommended.

Caution: Pesticides can be injurious to humans,

domestic animals, desirable plants, and fish or other

wildlife, if they are not handled or applied properly.

Use all pesticides selectively and carefully. Follow

recommended practices for the disposal of surplus

pesticides and pesticide containers.

Wood Handbook

Wood as an Engineering Material

Forest Products Laboratory

USDA Forest Service

Madison, Wisconsin

Contents

Preface v

Commercial Lumber

Hardwood Lumber 5–1

Softwood Lumber 5–7

Purchase of Lumber 5–12

Commonly Used Lumber Abbreviations 5–18

References 5–20

Acknowledgments vii

Contributors xi

Characteristics and Availability of

Commercially Important Wood

Timber Resources and Uses 1–2

Species Descriptions 1–3

U.S. Wood Species 1–3

Imported Woods 1–17

References 1–34

Lumber Stress Grades and Design Properties

Responsibilities and Standards for Stress

Grading 6–2

Visually Graded Structural Lumber 6–3

Machine-Graded Structural Lumber 6–7

Adjustment of Properties for Design Use 6–11

References 6–14

Structure of Wood

Bark, Wood, Branches, and Cambium 2–1

Sapwood and Heartwood 2–2

Growth Rings 2–2

Wood Cells 2–3

Chemical Composition 2–3

Species Identification 2–4

References 2–4

Fastenings

Nails 7–2

Spikes 7–8

Staples 7–8

Drift Bolts 7–9

Wood Screws 7–9

Lag Screws 7–11

Bolts 7–14

Connector Joints 7–18

Multiple-Fastener Joints 7–24

Metal Plate Connectors 7–25

Fastener Head Embedment 7–26

References 7–27

Physical Properties and Moisture Relations

of Wood

Appearance 3–1

Moisture Content 3–5

Shrinkage 3–7

Weight, Density, and Specific Gravity 3–11

Working Qualities 3–15

Decay Resistance 3–15

Thermal Properties 3–15

Electrical Properties 3–21

Coefficient of Friction 3–22

Nuclear Radiation 3–23

References 3–23

Structural Analysis Equations

Deformation Equations 8–1

Stress Equations 8–4

Stability Equations 8–8

References 8–11

Adhesive Bonding of Wood Materials

Adhesion to Wood 9–1

Surface Properties of Wood Adherends 9–2

Physical Properties of Wood Adherends 9–6

Adhesives 9–9

Bonding Process 9–15

Bonded Joints 9–18

Testing and Performance 9–20

References 9–23

Mechanical Properties of Wood

Orthotropic Nature of Wood 4–1

Elastic Properties 4–2

Strength Properties 4–3

Vibration Properties 4–25

Mechanical Properties of Clear Straight-Grained

Wood 4–26

Natural Characteristics Affecting Mechanical

Properties 4–27

Effects of Manufacturing and Service

Environments 4–34

References 4–44

iii

Wood-Based Composites and Panel Products

Scope 10–2

Types of Conventional Composite

Materials 10–3

Adhesive Considerations 10–3

Additives 10–4

General Manufacturing Issues 10–4

Standards for Wood–Based Panels 10–4

Plywood 10–6

Particle and Fiber Composites 10–13

Wood–Nonwood Composites 10–24

References 10–30

Finishing of Wood

Factors Affecting Finish Performance 15–1

Control of Water or Moisture in Wood 15–9

Types of Exterior Wood Finishes 15–14

Application of Wood Finishes 15–19

Finish Failure or Discoloration 15–24

Finishing of Interior Wood 15–30

Finishes for Items Used for Food 15–32

Wood Cleaners and Brighteners 15–33

Paint Strippers 15–33

Lead-Based Paint 15–35

References 15–36

Glued Structural Members

Structural Composite Lumber 11–1

Glulam 11–3

Glued Members With Lumber and

Panels 11–12

Structural Sandwich Construction 11–16

References 11–21

Use of Wood In Building and Bridges

Light-Frame Buildings 16–1

Post-Frame and Pole Buildings 16–4

Log Buildings 16–6

Heavy Timber Buildings 16–6

Timber Bridges 16–9

Considerations for Wood Buildings 16–10

References 16–14

Drying and Control of Moisture Content

and Dimensional Changes

Determination of Moisture Content 12–1

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