BC7 Flashcards
dimensional lumbar
available is 8-24 feet in 2 foot increments
tensile strength of wood
comparable to some types of steel on the basis of strength to unit weight
defects in wood reduce this comparison
standard tensile strength is 700 psi
moisture content of lumber
usually 19% or less
amount of moisture expressed as specific gravity
strength of wood
stronger parallell to grain than against
compressive strength parallel to grain is 325-1700 psi
laminated wood
flat strips of wood joined together by glue
glue laminated beams
butt joint-cannot be used with tensile stress
scarf and finger joints- can take tensile stress
thickness of beams ranges from 3/4 to 2 inches and lengths up to 100 ft
have structural integrity of solid wood under fire
glum beams
heavy timber construction with greater lengths
react like solid beams to fire
heat has no effect on adhesives
structural composite lumbar
SCL-outer and inner fibers of log
laminated veneer lumbar (LVL) sheets of veneer peeled from outer portions of log used in I beams and joists 1 3/4 to 3 1/2 inches thick
parallel strand lumbar (PSL) made from veneers not as uniform as LVL 2-8 ft in length strongest of the three heavily loaded columns and long spans
Laminated strand lumbar (LSL) made with strands up to 12 inches in length short span beams and columns
thermoplastic composite lumbar
made from wood fiber and polyethylene or polyvinyl chloride
boards like sawn lumbar
not intended for structural framing
outside decks and railings
resistant to weather
flame spread rating of 80
melts like plastic
plywood
4-8 feet
made from rotary sliced layers from rotating logs and glued together
direction of the grins is aligned at right angles to each other
used for
sheathing
concrete framework
webs of composite beams
hulls of ships
non veneered panels
oriented strand board (OSB) 3-5 layers of wood particles
oriented the same direction in each layer
stronger than other 2
used in sheathing and sub flooring
particleboard- not used for structural
can be used for lateral force resisting diaphragms
flooring in mobile homes
particles range from 1 inch to very fine
single or multilayer 8-40 ft
waterboard- similar to particle board but larger wafer like pieces
composite panels
insulation and structural support
structural insulated panel (SIP)
outer OSB panels and foam inside
inside is expanded posystyrene or polyerythane
inner core up to 1 ft
studs are not used
r value
measure of the ability to insulate
exterior insulation and finishing systems (EIFS)
code requires foam includes a facing that serves as a thermal barrier such as gypsum wallboard
noncombustible materials used for insulation
glass wool and rock wool in batts or blankets
fiberglass
older vermiculite
loose forms of insulation
granulated rock wool
mineral wool or glass wool blown into stud spaces or manually packed
cellulose fiber and shredded wood treated with water soluble salts
