CE EXAM 2 WOOD
What is meant by a structural panel span rating of 32/16? What types of wood products are rated this way?
A structural panel span rating of 32/16 allows for the use of different wood. A rating of 32/16 states that the panel maybe used as roof sheathing over rafters spacing 32 inches apart or as subflooring over joist spaced 16 inches apart. The long dimension of the sheet must be placed perpendicular to the length of the supporting member. Types of wood products that are rated this way are plywood, composite, or OSB.
What method of slicing is used for structural plywood panels? What is a common method for hardwood veneers destined for fine architectural woodwork?
the method of slicing for structural plywood panels is called rotary slice. Common method for hardwood veneers destined for fine architecture woodwork is sliced veneer.
What are the two basic requirements for type IV Heavy Timber Construction in the international building code?
the wooden structural members must meet certain minimum size requirements and its exterior walls must be constructed of noncombustible materials.
non-load bearing wall
wall can only carry it own weight in a concrete or steel structural frame.
Shear Connection
web of the beam is joined to the column
a sample 80-foot long 2 by 4 weighs 10 pounds. After drying in an oven, it weighs 8 pounds. What was its moisture content before drying? In its original condition, was it adequately seasoned for use as structural framing member.
In its original condition, it was not adequately seasoned for use as a structural framing member because a structural framing member must be seasoned to 15% or below. MC = ((weight wet - weight dry)/weight dry)*100) MC = ((10-8)/8)*100) MC = (2/8)*100 MC = 25%
Moment Connections
flanges of the beam are joined to the column.
What are the advantages of using structural composite lumber rather than solid lumber?
structural composite lumber makes use of wood materials that are rapidly renewable and if not used, might be treated as waste. They also provide many of the benefits of glue-laminated wood which include, structural strength up to three times that of conventional solid material, dimensional stability, availability of large sizes and long lengths, and consistent quality.
Importance of Mortar?
-Cushions masonry units -ensures uniform bearing -seals joints between units -minimizes the flow of air and water
Purpose of Joint reinforcing in CMU
-Resist shrinkage -increase compressive strength -resist seismic forces
Give three advantages of wood-plastic composites in comparison to solid lumber.
-more consistent material quality - freedom from defects and distortion - superior resistance to moisture.
Ingredients of mortar?
-portland cement -aggregates -hydrated lime -water
Name three wood species that have naturally decay-or-insect-resistant heartwood.
-redwood -cedar -black locust
Why are nails the most common fasteners used in wood construction
-they are inexpensive, - require no predrilling of holes - can be installed extremely rapidly.
load-bearing
Bears the load of the entire structure
What is one common use for softwood lumber? What is on for hardwood lumber?
Softwood lumber is most commonly used for building framing and hardwood lumber is most often used for furniture.
In the tree, what are springwood and summerwood cells? How do they differ?
Springwood Cells: - favor rapid growth due to plentiful of ground water and cooler air. - cells are larger and less dense compared to summerwood. Summerwood Cells: - Growth is slower due to the heat of summer and scarcity of water. - summerwood is stronger and stiffer than springwood.
Glue laminated Structures
Strength up to three times that of solid lumber longer lengths resistance for water and moisture consistent quality
Discuss the changes in moisture content and the effect of these changes on a piece of dimension lumber from the time the tree is cut, through its processing, and until it has been in service in a building for an entire year.
growing wood holds a quantity of water that can vary from 30% to as much as 300% of the oven-dry weight. After a tree is cut, this water begins to evaporate. The free water leaves the wood through evaporation and the wood now contains 26 to 32 percent moisture held in the cellulose of the cell walls. As the water bound begins to evaporate as well, the wood starts to shrink, causing the strength and stiffness of the wood to increase. Therefore, as the moisture content decreases, the strength, shrinkage, and stiffness increases.
What are the differences between plainsawn and quartersawn lumber? What applications are appropriate for each?
plainsawn: - annual growth rings within the board varies along its width, with large portions of the boards wider face dominated by a grain pattern in which annual rings are oriented close to the parallel with the face. - more affordable and produced faster Quartersawn: - the annual growth rings run more consistently perpendicular to the piece's wider faces. - less appropriate in applications such as shoring an exterior siding but are also more expensive due to the greater amount of waste generated through the process. - reserved for hardwoods such as furniture, shoring, interior trim, during which the expenses are justifiable.
Why are screw preferable to nails for fastening wood?
screws create a greater clamp force between joined pieces and have greater holding power. They are inserted with greater precision and can be backed out and reinserted if it needs adjustment or remounting.
Name three softwood species and three hardwood species.
softwood: -alpine -balsam -douglas Hardwood: -beech -birch -black walnut
