Chpt 7 Flashcards
Wood is stronger in a direction ____ to the grain than against the grain
Parallel
The allowable compressive strength parallel to the grain varies from _____ for commercially available grades and species of lumber
325 to 1700 psi
On the basis of strength to unit weight, wood has a tensile strength comparable to
Steel
Wood has a useful
Tensile strength
Typical defects in wood, however, greatly reduce this comparison, so the allowable tensile strength of wood is about
700 psi
It is possible to dry lumber to any moisture content,but most structural lumber has a moisture content of
19 percent or less
Can be defined as lengths of squared would also known as dimensional wood use for construction
Lumber
The grading of _____ permits it to be used more economically by allowing the designer to specify a higher grade where it is needed and a less expensive, lower grade is less critical members
Lumber
Boards have a nominal thickness of_____or less
2 inches
Dimensional lumber has a nominal thickness of up____ or more
2 to 4 inches or more
Laminated wood members are produced by joining flat strips of wood with glue. The beams produced by this method are known as
Glulam beams
The advantage to producing _______ is that sizes and shapes can be produced that are not available from solid pieces cut from logs
Laminated structural members
Three types of joints can be used to join laminated members end to end. These are the _____
Butt joint
Scarf joint
Finger joint
The ____ is easy to produce but cannot be used where tensile forces are to be transmitted along the length of the beam.
Butt joint
The _____ can be used to transmit tensile forces
Scarf and finger joints
Is produced by peeling sheets of veneer from the outer portion of the log
Laminated veneer lumber
Is made from the outer most veneers peeled from a log that are not as uniform as those used in LVL
Parallel strand lumber
Is produced by taking long strands of word up to 12 inches in length and bonding them with a resin in a steam pressing process
Laminated strand lumber
Is the strongest of the SCL products and can be used for heavily loaded columns and long spans
PSL parallel strand board
Finds applications in I joints and beam sections 1 3/4 to 3 1/2 inches thick
LVL laminated veneer lumber
Is typically used for short span beams and columns
LSL laminated strand lumber
Are made up of several thin layers or veneers that are rotary sliced from rotating logs and glued together
Plywood panels
Uses long strand like wood particles that are compressed and glued into three to five layers
Oriented strand board
Is made from wood particles bonded with synthetic resins under heat and pressure
Particleboard
Particleboard is sometimes refered to as
Flake board, chipboard, shavings board
Because it can be manufactured in large sheets,_____ is used for flooring and manufactured and mobile homes
Particle board
Consist of a face and back panel such as plywood or OSB bonded to a central core material
Composite panels
Wood panel products are graded for their structural use in their exposure durability. A great game appears on the back of the structural panel that indicate it’s intended structural application and it suitability for exposure to water. The span rating of_____indicates that the panel may be used as roof sheathing on rafters 3 inches apart or as sub flooring on joists 16 inches apart
The span rating of 32/16
Wood trusses are sometimes categorized as
Light frame trusses
Heavy timber trusses
Split ring trusses
Are made up of 2 inch nominal members that are all in the same plane
Light frame trusses
Pose a special problem for firefighters because the relatively slender wood members used to construct the trust will fail earlier in a fire then the heavier members used in the past
Light frame wood trusses
Are made up of members up to 8 to 10 inches
Heavy timber trusses
A _____ makes use of a short circular piece of steel within and between two adjacent wood members to transfer the load between the members
Split ring trusses
With a ______, a bolt with a thrust washer is run through the split ring to hold the members together
Split ring connector
One serious and fundamental drawback to wood as a building material is its
Combustiblity
Ignition temperature for wood are difficult to measure precisely because the ignition temperature of wood is affected by such variables as the following
Density of wood Size and form of the wood Moisture content Rate of heating Nature of heating source Air supply
Is the thermal decomposition of wood and begins at a temperature somewhere below approximately 392 degrees F
Pyrolysis
The ____ of a fuel is the total amount of thermal energy that could be released if the fuel were completely burned
Heat of combustion
The heat of combustion is measured in
BTUs British thermal units
The severity of the fire is not determined only by the total amount of fuel available. The rate at which a fuel is consumed and, therefore, the rate at which energy is released determines
Fire growth and severity
A greater surface area for a given mass of wood permits a more rapid combining a fuel vapors and air for combustion and, therefore an overall greater rate of burning
Surface to mass ratio
The relationship between surface area and mass is the
Surface to mass ratio
resists ignition and has increased fire endurance when compared with non-treated wood
Fire retardant treated wood
The two main methods of fire retardant treatment are
Pressure impregnation and surface coating
Is used primarily to reduce the surface burning of wood ie the flame spread rating
Surface coating
Most _____ operate by accelerating the formation of charring in the wood when the wood is exposed to heat
Fire retardant chemicals
The chemical reaction of the ______ is intended to occur at temperatures lower than those that are developed in fires
Fire retardant
Is a wood like product produced from wood fiber and poly ethylene or polyvinylchloride
Thermoplastic composite lumber
It’s main application is in the construction of outside decks and railings
Thermal plastic composite lumber
Thermal plastic composite lumber is a combustible product with a flame spread rating of
80
Is very commonly used in frame structural systems
Wood
The wood framing system is most frequently encountered can be broadly classified into two basic types
Timber framing and light wood framing
Because of labor costs and limitations in the basic strength of the wood, most wood frame frame buildings do not exceed
Three stories
Because they are more massive and have a lower surface area to mass ratio, ____ display greater structural endurance under fire conditions than members used in light frame construction
Heavy timber
In modern construction, ____ are used only in rare cases where the designer desires a particular artistic or quaint appearance
Mortise and tenon joints
The glulam beams are used frequently in _____ construction where greater lengths are required
Heavy timber
Is a form of wood frame construction in which the columns and the beans are of dimensions less than those used in heavy timber framing but greater than those used in light frame construction
Post and beam
The most popular form of wood framing is known as
Light wood frame construction
In ____, the exterior wall studs are continuous from the foundation to the roof
Ballon framing
The vertical combustible spaces between the studs in _____ provide a channel for the rapid communication of fire from floor to floor.
Ballon fame construction
In ____ the exterior wall vertical studs are not continuous to the second floor
Platform framing
To prevent the rapid spread of fire through the concealed spaces within combustible construction, building code require
Fire stopping
In a platform frame building, the plate installed on the top of the studs provides an inherit _____ that will act to block the spread of fire from floor to floor within the walls
Fire stop
Building codes require ____ in the attic spaces of combustible construction
Draft stopping
Is installed on the outside of the studs to provide structural stability, insulation, and an underlayer for the siding
Sheathing
A layer of ____ is provided between the sheathing and the siding to act as a vapor barrier
Building paper
A wood frame building, like other buildings, can be provided with an exterior facing of brick. Such construction is termed
Brick veneer
One frequently use rule is that in a brick bearing wall every sixth course of brick is a ____with the ends of the brick facing out
Header course
An ____ enhances appearance and provides a measure of thermal insulation
Interior finish
Where a degree of fire resistance is required, the ____ materials most commonly used are gypsum board or plaster
Interior finish
When the structural framing of a wood frame building, including the floor and roof construction, is provided with protection to achieve a 1 hour fire resistance, the building can be classified as
Type Va
If a wood frame building is equipped an automatic sprinkler system, the code may permit the elimination of the
1 hour structural fire resistance
The combustible voids inherent in ____ provides paths for the rapid spread of fire through a structure
Light wood frame
As urban development moves into rustic wildland areas, a serious problem develops. Fires in the often highly flammable vegetation can rapidly engulf and destroy structures. Structures of light wood frame construction are especially vulnerable. The problem has been particularly serious in the western part of the United States. To protect property in these areas jurisdictions have adopted code requirement to make buildings
Ignition resistant
Is intended to decrease the vulnerability of structures to exposure from wildland fires
Ignition resistance
The distinguishing characteristic of a wood frame building is that the basic structural system is
Combustible
