Chapter 10- Noncombustible Construction Flashcards
What, then is the difference between noncombustible and fire resistive construction? The answer is simple–the level of fire resistance (fire rating) assigned to the structural __, __, __, and __.
Frame
Walls
Floors
Roof
Many noncombustible buildings are __-__ stories in height, with the maximum height being __ stories for certain types of occupancies. Fire resistive construction, by comparison, is permitted to be of unlimited height.
1-3
12
Although the use of concrete is found in some buildings of noncombustible construction, noncombustible construction relies heavily on the use of __ for its structural system, including the roof and floor framing.
Steel
The use of __ in Type 2 construction is typically limited to __ walls and __ enclosures.
Concrete
Exterior
Shaft
Steel is tremendously strong. Its Modulus of elasticity (a measure of its ability to distort and restore) is about __ million pounds per square inch–far more than any other material.
29
Steel’s compressive strength is equal to its tensile strength. Its __ strength is about __ of its tensile strength.
Shear
3/4
The heat evolved by a fire can be triaged–that is, considered and treated according to priority needs. In reverse priority, this heat can be classified as follows:
- Heat leaving the structure
- Heat being evolved from contents that are burning
- Heat being absorbed by contents or structural elements that will be ignited or caused to fail
The following abbreviations are used for different shaped steel members:
C: channels CB: castellated beams L: angles S: America Standard (I beam) W: wide flange beams and columns WT: structural tees
__ frames are a cousin to the arch and are used to achieve wide clear spans.
Rigid
In the rigid frame, the column is __ at the base and tapers to its __ point at the top where it meets the roof rafter.
Narrow
Widest
This rafter is also tapered so that it is narrow at the __ and wide where it joins the __.
Ridge
Column
Rigid frames can provide clear spans of about __ feet.
100
The better the building is tied together to resist __ load, the more likely it is to suffer __ collapse due to fire distortion.
Wind
Progressive
__ wall panels can be used on any framed building and, in fact, are used on many concrete buildings.
Metal
The use of lightweight galvanized steel studs for exterior walls has surged. Shaped like the letter __, these studs are held in place with __ shaped tracks on top and bottom.
C
U
Steel will expand __ to __ percent in length for each 100 degrees F rise in temperature.
0.06 to 0.07
Recent tests conducted by the National Institute of Standards and Technology (NIST) of a typical basement room fire reached 1500 degrees F in __ minutes, reflecting the presence of today’s heavy plastic fire loads rather than any special significance of basements.
5
In a fire equivalent to the standard test fire, the bar joists generally will fail in about __ minutes.
7
A number of options are open to the designer to deal with these characteristics of steel as they relate to fire risk:
- Ignore the problem
- Rely on inadequate code enforcement
- Take a calculated risk
- Protect (insulate) the steel
- Protect the steel with sprinklers
- Protect the steel with an internal water cooling system
- Locate the steel out of range of the fire
__ and __ on highways provide a good example of unprotected steel that is vulnerable to an occasional gasoline or oil truck fire.
Bridges
Overpasses
In some building codes, steel used to support roofs at a certain distance above the floor (usually about __-__ feet) does not require protection. Atria roofs over __ feet are given this exemption as well.
20-30
55
The lack of fire protection for unprotected steel may reflect a calculated risk taken by the building’s developers and managers. For our purposes, there are three classes of calculated risks:
Financial or economic
Engineering
Forget it
In recent years, the __ roof (composed of ethylene propylene diene monomer (EPDM)) has increased in popularity in Type 2 construction.
Rubber
Another relatively new type of roof is the __ __ (mod bit) roof. In this construction technique, a traditional built up roof is modified by the addition of synthetic polymers to reinforce the roof.
Modified bitumen
(Factory Mutual tests on metal deck roof assemblies have shown that it takes only __ degrees F for __ minutes for heat impinging on the surface of steel decking to start a self sustaining roof fire. This fire is independent of the original fire.)
800
5
Steel structures can be divided into four types:
- Unprotected
- Dynamically protected
- Passively protected
- Passive/dynamic combination protection
Asphalt coating that is combustible and used as a weather protective coating on galvanized steel walls.
Asphalt asbestos protected metal (AAPM)
Plates fewer than 6 inches in width; may be square or round.
Bars
A large hollow column built from steel plates.
Box column
A tee where the end of the cutoff is thickened.
Bulbtee
An upright partition that divides a ship into compartments and is meant to prevent the spread of leakage or fire.
Bulkhead
A wide flange beam that has been cut in half in a zig zag pattern and then welded back together in an offset manner, creating a new, deeper beam.
Castellated beam
Noncombustible material often used for friable construction.
Cement asbestos board
Steel structural component that has a square U shaped cross section.
Channel
Void space made by utilizing deep parallel chord trusses.
Interstitial space
Column made of vertical units connected with diagonal pieces.
Lattice column
Embedded into the surface.
Peened
Concrete panels that are precast and brought to the construction site.
Precast prestressed concrete panels
Beams set at right angles to trusses or roof rafters to provide support for lightweight roofing.
Purlins
Diagonal columns that brace an entire structure.
Rakers
Girders that tie wall columns together in a framed building.
Spandrel girders
Distance between the top of one window and the bottom of the one above.
Spandrel space
Embossed steel; will transfer heat in either direction.
Tin ceiling
A horizontal beam that ties rows of soldier beams together.
Waler
I beams that have flanges wider than standard I beams.
Wide flange shapes
