chapter 9 Flashcards
steel construction
what have largely replaced wood beams and trusses
steal ones p. 239
2 primary metals alloyed in steel are
iron and carbon
common structural steel has less than what of carbon
3 tenths of 1 %
cast iron has a carbon content of
3-4 %
higher carbon content of cast iron makes things
more brittle
what has been completely displaced by steel in modern building
cast iron
how does cast iron tent to fail
by fracturing from impact loading rather than by yielding
strongest building material
non-rotting, resist to aging, dimensionally stable
consistent Quality
expensive
ARE basic properties of ?
STEEL
inherent disadvantages of steel is
tendency to rest when exposed to air and moisture
ways to ‘’’ from rust `painting w/ rust inhibiting paint
coating the martial w/ zinc and aluminum
adding alloy element that resist rust
protect
adding molybdenum to steel will
strengthen it
adding vanadium to steel will x2
strength and toughness
adding manganese to steel will resistance of
resistance of steel to abrasion p. 240
mixture of 2 or more metals fused to and dissolve into each other to enhance properties
alloy
lower carbon content of steel compared to cast iron results in a material that is
ductile
the ductility of steel is allows for it to be shaped by
rolling
what steel can be used for members that have thin cross sections, such as floors and roof decks and wall studs
cold rolled steel ( shaped after its cools below its recrystallization temp)
a measure of a metals ability to be drawn, hammered thin or rolled into shapes without breaking
ductility
common structural steel
astm a 36p. 241
expansion for slender members such as beams and colums can be determined through a property called
coefficient of thermal expansion
steel unable to push lateral constraints will
weaken, bow or buckle and fail
the speed of ‘’ depends on several factors including:
type of steel
mass of steel
load supported
type of connection used to join members
intensity of exposing fire
failure
steel is a good conductor of heat b/c its a
hvy material
density of steel is around ‘’ PER CUBIC FT
490 per cubic ft
what members of steel can be expected to fail early when exposed to fire
bar joist or slender trusses p. 242
no matter its mass, steel is not inherently
fire resistive
usually way to protect steel from fire is
adding insulting material
steel colum incased in 3 inch of concrete will have a fire resist of
4 hours
coating used to increase fire resistance rating of Structural components
spray applied fire resistive material p. 243
fireproofing can vary from ‘’ in thickness to produce fire resistants
7/8 to 1 7/8
what has not be used in SRFMS since 70/s
asbestos
cementitious materials are produced in various formulations ingredients include:
pc
g
p
v
portlan cememt , gypsum, perlite and vermiculite
what can be used as an insulting material either in form of flat boards or plaster
gypsum
process that heats a substance to a high temp but below melting point
calcined
process of driving free and chemically bounded water out of gypsum( water turns to steam upon exposure to fire and in doing so absorbs the heat )
calcination
gypsum board is available in 2 types
regular and type x
gypsum with no special additives is
regular
gypsum with additive is ( to resist fire)
type x p. 244