Ch 10 Lightweight Steel Roof and Floor Collapse Flashcards
Steel starts to distort and lose strength during a typical structure Fire where flames reach how many degrees? Pg 143
1000 to 1100 degrees
It requires more than how many degrees to melt steel? Pg 143
2400 degrees
Three common methods to protect steel from the heat of fire are? Pg 145
•best method to protect steel is Encasement of the steel with concrete.
•The installation of a fire retarding ceiling between the occupancy and the steel above.
•the most popular, but least effective, method, applying a spray on fire regarding (SFRM) material over the entire surface of the steel.
Four factors determine the speed with which unprotected steel will fail during a fire? Pg 151
•temperature of the fire
•the load stress
•the steel thickness
•fire size
There are two common types of roof deck used a above the fluted steel deck of a bar joist roof or C beam support system? Pg 153
lightweight insulation or a precast concrete plank.
What strategy should be considered in an unprotected Type II steel building?
p. 149
Horizontal ventilation and defensive exterior attack
Which of the following is NOT cited as a reason the spray-on fire retarding material fails to protect steel from the heat of a fire? p. 147
Cleaning strips the steel of its adhesive properties
Where should the firefighter place his feet when cutting vent holes in a flat roof? p. 142
Roof side of the cuts
Up to what distance apart can open-web steel bar joists be spaced? p. 151
8 feet
What is the roof designed to support?
p. 152
Rain load
What is done to increase the strength of steel? p. 143
Bend it into shape
How much of its load carrying capacity will steel lose at 1,100 degrees Fahrenheit (593 degrees Celsius)?
p. 152
40 percent
Which is the best method to protect steel, from the firefighter’s point of view? p. 145
Encase it in steel
What size floor or roof beam is created with the C-beam? p. 143
20 foot
What causes spalling in concrete?
p. 145
Expansion of moisture in the concrete into steam
What may fall on firefighters operating under a membrane
ceiling if the suspension system is not properly constructed? p. 146
Ceiling
Which is often the cause of failure of the C-beams in the early stages of a fire? p. 150
Size-up misjudgment
What is being replaced in modern lightweight construction by the bar joist truss and C-beam? p. 143
Solid I-shaped beam
What temperature must be reached for steel to melt? p. 143
2400 degrees Fahrenheit (1 315 degrees Celsius)
Which property of the spray-on fire retarding material has become more important that previously thought?
p. 148
Adhesion
Up to what distance on center were wood joists spaced in the past? p. 151
24 inches
Which is the most popular but least effective method to protect steel from the heat of fire? p. 145
Applying a spray-on fire retarding material
Which material is NOT included in the
spray-on-fire-retarding material?
p. 146
Asbestos based liquid
What characteristic of large-size steel allows it to transfer the heat of a fire to a cooler interior region of
the steel? p. 153
Heat sink
Which of the following is NOT a factor that will determine how fast unprotected steel will fail during a fire? p. 151
Building size
Which of the following does steel NOT do during a fire? p. 143
Melt
What temperature can a typical structure fire reach? p. 145
1700 degrees
Which shape does the spray-on fire retarding material have problems adhering to? p. 148
Round
