Flashcards in Dunn - Chapter 15, 16 & 17 Deck (28):
What are the three ways that a wood frame building can collapse during a fire?
a) 90 degree angle
b) Lean over
c) Inward-outward collapse
How is a 90 degree angle wall collapse signaled?
By the corners of the falling wall splitting apart from the remaining walls.
How is a lean-over collapse indicated?
By the burning structure SLOWLY starting to tilt or lean to one side.
Which collapse is the most dangerous?
The inward-outward collapse is the MOST DANGEROUS because it is sudden, it gives no visible warning signs prior to failure and unlike most other building failures, it may involve the collapse of two, three or four walls SIMULTANEOUSLY.
What are the corner safe areas?
They are the four flanking zones around a burning wood frame building.
Which type of wood constructed building presents the GREATEST firefighting danger?
Braced-frame wood constructed buildings.
If a fire weakened the bearing wall studs of all three floors AT THE SAME TIME, what would occur?
The GROUND floor wall studs would fail first.
What are the four most widely used methods of wood-frame construction over the past 200 years?
a) Braced frame
b) Balloon frame
c) Platform frame
d) Lightweight wood frame construction
Braced frame construction
Sometimes called "post & girt" construction.
Vertical timbers called "posts"
Horizontal timbers called "girts" (found at each floor level)
Connected together by MORTISE & TENON joints.
What is an indication of "balloon frame" construction?
The unobstructed opening b/t each stud in the exterior wall, extending from the foundation sill to the attic cap, is an indicator of balloon construction.
The MOST widely used method of wood-frame construction.
Platform construction is SUPERIOR to balloon or braced frame construction because there are no concealed wall voids that extend for more than one floor.
L/W wood truss construction
It is INFERIOR construction
It suffers floor and roof collapse.
What is the danger of L/W wood truss construction?
The danger is early floor and roof collapse of the truss floors and roofs.
What are the three contributing causes of wood-frame building collapse?
1) Fire destruction of bearing walls,
2) The mortise & tenon joint of a braced-frame wooden building
3) The overload of an exterior wooden wall.
During a fire in a building under construction that is exposing the crane, what should the size of the collapse zone be?
A collapse zone EQUAL TO the height of the crane must be set up.
What is "Spalling" collapse?
The failure of the outer layers of concrete, caused by the rapid heating of moisture inside the concrete.
In some "fast track" construction projects, one concrete floor is poured every?
How many days does it take for concrete to reach its MAXIMUM STRENGTH?
When do most serious fires in a building UNDER CONSTRUCTION and the MOST SERIOUS floor collapses occur?
They occur during a fire in the formwork.
Worker shanties in buildings under construction are required to comply with what regulations?
a) Non-combustible construction
b) At least 30' from the building under construction
c) Cannot be grouped together.
What is the recommended strategy to extinguish fires in formwork supporting floors?
The use of outside aerial master streams.
All F/F's should be removed from the building during this operation.
What is the major cause of fire extension of a framework fire in a cast-in-place building under construction?
They will also be blown around and dropped down onto exposures and smaller building causing incipient fires.
Where is the destructive pressure of a large caliber stream the greatest?
In the area where the water leaves the nozzle.
What is the most serious collapse danger of a LCS?
The large volume of water it discharges into a burning building.
When a LCS strikes a BRICK WALL in smoke......
It makes a "SPLATTERING" sound made by the stream striking the wall.
When a LCS strikes the sidewall of a WOODEN building....
A "DRUM" sound is made by the stream striking the wall.
When a LCS stream enters a window......
The sound of the LCS is REDUCED and only a distant rumble is heard.