Wood Properties and Tree Types
30 Questions
13 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a characteristic of deciduous trees?

  • They have no bark
  • They have broad leaves and shed them in the fall (correct)
  • They have needles
  • They have no leaves

What is the purpose of reducing the stresses in the samples at failure?

  • To determine the elasticity of the wood
  • To determine the strength of the wood
  • To establish the cost of the wood
  • To provide a safety factor of approximately 2.5 (correct)

What is the main composition of wood?

  • Gum
  • Resin
  • Lignin
  • Cellulose (correct)

What is the function of the cambium layer?

<p>To produce new fibers that increase the diameter of the tree (C)</p> Signup and view all the answers

What is heartwood composed of?

<p>Dead fibers (D)</p> Signup and view all the answers

What is the purpose of the bark?

<p>To protect the growing cells from insects (C)</p> Signup and view all the answers

What is the purpose of testing small, perfect samples of wood?

<p>To determine the stresses at failure and the modulus of elasticity for each species (A)</p> Signup and view all the answers

What is the safety factor used to reduce the stresses in the samples at failure?

<p>Approximately 2.5 (D)</p> Signup and view all the answers

What is the purpose of the National Design Specification for Stress-Grade Lumber and Its Fastenings?

<p>To provide grades established for each species of wood with usable allowable stresses for each grade (A)</p> Signup and view all the answers

What is the standard used for testing small, perfect samples of wood?

<p>ASTM D2555 (D)</p> Signup and view all the answers

What is the purpose of the Lumber Classification Standards?

<p>To classify lumber according to appearance, strength, shape, and use (B)</p> Signup and view all the answers

What is the title of the standard that includes basic allowable stresses for clear lumber under long-time service at full design load?

<p>ASTM D245 (C)</p> Signup and view all the answers

What is the primary function of the Southern Forest Product Association?

<p>Providing grading rules for pine species in the United States (D)</p> Signup and view all the answers

Which of the following agencies provides grading rules for Sitka spruce and Douglas fir?

<p>The National Lumber Grades Authority (A)</p> Signup and view all the answers

What is the minimum width required for a piece of lumber to be considered a board?

<p>2 in. (D)</p> Signup and view all the answers

What is the term that includes all finished or semi-finished wood shaped with parallel longitudinal surfaces?

<p>Grading Lumber (B)</p> Signup and view all the answers

What is the primary use of hardwood lumber purchased from local mills?

<p>Construction (C)</p> Signup and view all the answers

What is the minimum thickness required for a piece of lumber to be considered Dimension Lumber?

<p>2 in. (A)</p> Signup and view all the answers

What is the primary consideration for grading factory and shop lumber?

<p>Usable and waste ratio (C)</p> Signup and view all the answers

What is the main difference between boards and dimension lumber?

<p>Usage and application (C)</p> Signup and view all the answers

Why is a smaller safety factor justified for repetitive members?

<p>They are assisted by surrounding members (A)</p> Signup and view all the answers

What is the primary characteristic of timbers?

<p>They are used for shoring earthwork or mine tunnels (D)</p> Signup and view all the answers

What is the purpose of stress grading for dimension lumber and timbers?

<p>To assign a grade based on strength (A)</p> Signup and view all the answers

What is the basis for grading boards?

<p>Appearance and defects (B)</p> Signup and view all the answers

What type of defect affects strength and is permitted only in the lower grades?

<p>Shakes (A)</p> Signup and view all the answers

What type of defect is caused by unequal shrinkage during seasoning?

<p>Cup and Crook (D)</p> Signup and view all the answers

Which type of defect is an accumulation of resinous material?

<p>Pitch (C)</p> Signup and view all the answers

What type of defect is a lengthwise separation of the wood caused by seasoning or flattening of cupped lumber?

<p>Checks (C)</p> Signup and view all the answers

What type of defect is a result of bark or missing wood on an edge or corner of a piece of lumber?

<p>Wane (B)</p> Signup and view all the answers

Which type of defect is not permitted in all grades?

<p>Shakes (C)</p> Signup and view all the answers

Flashcards

Bark

The outer layer of a tree that protects the growing cells and has no structural value.

Cambium Layer

A thin, growing layer between the bark and sapwood where new cells are formed, increasing the tree's diameter.

Cellulose

A structurally sound material found in all wood species that provides strength and support.

Heartwood

The innermost part of a tree, consisting of dead fibers, which is darker in color due to resins, gums, and minerals.

Signup and view all the flashcards

Pith

A soft vein of tissue that runs the length of the tree, with no strength.

Signup and view all the flashcards

Deciduous Tree

A type of tree that sheds its leaves in the fall.

Signup and view all the flashcards

Coniferous Tree

A type of tree that doesn't shed its leaves. They often have needles instead of broad leaves.

Signup and view all the flashcards

Dimension Lumber

Lumber used for joists, studs, and rafters, typically smaller in size than timbers.

Signup and view all the flashcards

Timbers

Lumber used for larger construction projects, such as beams or columns.

Signup and view all the flashcards

Boards

Lumber used for various purposes such as floors, walls, and panels.

Signup and view all the flashcards

Fibers

Long, narrow, hollow cells in wood that grow outward, increasing the tree's diameter.

Signup and view all the flashcards

Grading Factors

Factors in grading lumber such as stains, cracks, knots, and other imperfections.

Signup and view all the flashcards

Lumber Grading

The process of categorizing lumber based on strength, appearance, and use.

Signup and view all the flashcards

National Design Specification (NDS)

Published standards which define allowable stresses for different grades and species of lumber.

Signup and view all the flashcards

Modulus of Elasticity

The ability of a material to deform elastically under stress.

Signup and view all the flashcards

Allowable Stress Testing

Testing small, perfect samples of wood to determine their strength limits.

Signup and view all the flashcards

Safety Factor

A safety factor applied to stress test results to account for imperfections and variability in lumber.

Signup and view all the flashcards

Wood Odor

A pleasant smell emitted by freshly cut wood.

Signup and view all the flashcards

Workability

The natural ability of wood to be worked with and shaped in various ways.

Signup and view all the flashcards

Shoring

The practice of using timbers to support underground structures like mines or tunnels.

Signup and view all the flashcards

Cup

A type of defect in lumber that appears as wavy or twisted grain, weakening the wood.

Signup and view all the flashcards

Check

A defect in lumber that appears as a crack extending across the grain, weakening the wood.

Signup and view all the flashcards

Shake

A type of defect in lumber that appears as a separation between the layers of grain, making the wood weaker.

Signup and view all the flashcards

Wane

A defect in lumber that appears as a tapered edge, making the wood weaker.

Signup and view all the flashcards

Split

A defect in lumber that appears as a crack along the length of the wood, making it weaker.

Signup and view all the flashcards

Pitch

A type of defect in lumber that appears as a knot or bulge, caused by a branch.

Signup and view all the flashcards

Pocket

A defect in lumber that appears as a hole or void in the wood, making it weaker.

Signup and view all the flashcards

Crook

A type of defect in lumber that appears as a bend or curve, making the wood weaker.

Signup and view all the flashcards

Study Notes

Wood Characteristics

  • Wood has universal appeal and is generally pleasant to work with, regardless of how it is cut or finished.
  • Wood has a pleasant odor when freshly cut.

Types of Trees

  • Deciduous trees (hardwoods) have broad leaves that shed in the fall.
  • Coniferous trees (softwoods) do not shed their leaves.

Tree Structure

  • Fibers consist of long, narrow, hollow cells that grow outward from the tree, increasing its diameter.
  • The cambium layer is a thin, growing layer between the bark and sapwood.
  • Heartwood is composed of dead fibers and has a darker shade due to resins, gums, and minerals.
  • Pith is a thin vein of soft tissue extending the length of the tree, with no strength.
  • Bark protects the growing cells from insects but has no structural value.

Wood Properties

  • Cellulose is a structurally sound material that makes up all wood species.
  • Allowable stresses for lumber are determined by testing small, perfect samples and reducing the stresses at failure to provide a safety factor of approximately 2.5.
  • Moduli of elasticity are published in ASTM D245.

Lumber Grading

  • The National Design Specification for Stress-Grade Lumber and Its Fastenings includes grades established for each species of wood with usable allowable stresses for each grade.
  • Lumber classification standards have been established for the classification of lumber according to appearance, strength, shape, and use.
  • Grading rules are provided by organizations such as the Southern Forest Product Association and the National Lumber Grades Authority.

Lumber Types

  • Dimension lumber is used for joists, studs, and rafters.
  • Timbers are used infrequently as part of a structure, and are often used for shoring earthwork or mine tunnels.
  • Boards are used for roofs, floors, siding, paneling, and trim.

Factors in Grading Lumber

  • Stains, checks, shakes, cup, crook, wane, splits, pitch, and pockets are all considered in grading lumber.
  • These factors affect appearance and strength, and are permitted to some extent in all grades.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Description

Test your knowledge of wood properties and types of trees, including deciduous and coniferous trees. Learn about the characteristics of wood and how it is classified. Improve your understanding of allowable stresses for lumber and safety factors.

More Like This

Wood Properties Quiz
10 questions

Wood Properties Quiz: Test Your Knowledge

RightFriendship avatar
RightFriendship
Wood Properties Quiz
5 questions

Wood Properties Quiz

PatriMossAgate6783 avatar
PatriMossAgate6783
Wood Properties Quiz
5 questions

Wood Properties Quiz

SatisfactoryMountain avatar
SatisfactoryMountain
Use Quizgecko on...
Browser
Open
Browser
Browser