Lecture 17

Question 1

Wood

Answer 1

Many structural and non-structural applications

Question 2

Where does the term lumber derive from?

Answer 2

Derived directly from logs and applies to wood products (Only solid pieces)

Question 3

Advantages of wood?

Answer 3

High strength-to-weight ratio of lumber. No need for heavy equipment for lifting and hoisting building components. Low cost, Simple

Question 4

What does a tree consist of?

Answer 4

Root structure, trunk, branches and leaves

Question 5

Cambium Layer

Answer 5

Where cell division takes place, between bark and outermost ring

Question 6

Heartwood

Answer 6

Interior dark colored region of tree trunk

Question 7

Sapwood

Answer 7

Light colored region of tree trunk

Question 8

What are the cells added during the wet and dry seasons called?

Answer 8

Earlywood and latewood

Question 9

Two broad categories of lumber

Answer 9

Hardwoods and softwoods.

Question 10

Hardwoods

Answer 10

Stronger than softwoods, flowering trees, hard broad leaves, deciduous, shedding and re-growing leaves

Question 11

Softwoods

Answer 11

Do not bear flowers, hard broad leaves, typically deciduous

Question 12

Isotropic

Answer 12

Having the same properties in all directions (Steel and concrete)

Question 13

Anisotropic

Answer 13

Not having the same properties in all directions (wood)

Question 14

Best direction in lumber

Answer 14

Stronger along the grain

Question 15

Where does the conversion of logs into finished lumber take place

Answer 15

In lumber mills, located close to the forests

Question 16

What are the four basic steps of the log to lumber process

Answer 16

1. Transportation of logs from the forest to the mill
2. Debarking of logs
3. Sawing the debarked logs into lumber
4. Surfacing lumber members smooth

Question 17

Flat-sawing

Answer 17

Sawing of larger diameter log in two directions yield several pieces of dimension lumber and timbers. Or can be in one direction giving primarily dimension lumber

Question 18

Quarter (radial) sawing of a log

Answer 18

More wasteful of wood than flat sawing

Question 19

Drying of lumber

Answer 19

Lumber has to be dried (or seasoned) Seasoning implies a controlled rate of drying.

Question 20

Fiber saturation point

Answer 20

The stage at which all the free water (cavity water) has evaporated and the bound water (cell water) has just begun to evaporate

Question 21

How do you find the moisture content?

Answer 21

The weight of water in wood divided by the weight of oven dry wood multiplied by 100

Question 22

Dry lumber vs Green lumber

Answer 22

Dry lumber (MC < 19%)
Green lumber (MC>20)

Question 23

Surfaced dry (S-DRY)

Answer 23

Piece of lumber (air or kiln) seasoned to a moisture content of 19% or less

Question 24

Surfaced green (S-GRN)

Answer 24

If the moisture content at the time of surfacing is more than 19%