WOOD - Materials for Civil and Construction Engineers - page 439

QUESTIONS AND
PROBLEMS

10.1 What are the two main classes of wood? What is the main use of
each class? State the names of two tree species of each class.
10.2 What is the difference between early wood and latewood? Describe
each.
10.3 A simple lab test for specific gravity on two samples of lumber indi-
cate that sample A has and sample B has Based
on this information alone, which wood sample would you choose as a
structural member for your construction project. Briefly explain why.
10.4 Discuss the anisotropic nature of wood. How does this phenomenon
affect the performance of wood?
10.5 Briefly describe the chemical composition of wood.
10.6 The moisture content of wood test was performed according to
ASTM D4442 procedure and produced the following data:
Weight of specimen in the green
Weight of oven-dry
Calculate the moisture content of the given wood.
10.7 What is the fiber saturation point? What is the effect of the fiber sat-
uration point on the shrinkage of wood in the different directions?
How does this phenomenon affect the properties of lumber?
10.8 A stud had dimensions of and a
moisture content of 150% when it was prepared. After seasoning,
the moisture content was reduced to 7%. If the tangential, radial,
and longitudinal directions of the grains are on the same order as
the dimensions indicated above, what are the dimensions of the sea-
soned stud if the moisture-shrinkage relation follows Figure 10.5?
10.9 A wood timber with a diameter of 1 inch has a moisture content of
5%. The fiber saturation point (FSP) for this wood is 28%. The
wood shrinks or swell is 1% in the radial direction for every 5%
change in moisture content below FSP.
a. What would be the percent change in the wood's diameter if the
wood's moisture is increased to 43%?
b. Would the wood swell or shrink?
c. What would be the new diameter?
10.10 Wood is cut at sawmills into a variety of products, with different sizes
and shapes for engineering applications. What are these products?
10.11 Construction lumber can be cut from the tree using one of two
methods or a combination of them. Name these two methods and
show a sketch of each. What is the main advantage of each method?

G = 1.12 G = 1.03.

condition = 266.7 g.

specimen = 152.1 g.

38.1 mm * 88.9 mm * 2.438 m