9- Building Construction- Steel Construction Flashcards
The primary two metals alloyed in steel are ____ and _____.
Iron and Carbon
Common structural steel has less than _____% carbon. In contrast, cast iron has a carbon content of _ - _%.
Structural steel- less than 3 tenths of 1%
Cast iron- 3-4%
Steel is relatively expensive, but ____ and other qualities enable it to be used in smaller quantities than other materials.
Strength
One inherent disadvantage of steel is:
The tendency to rust when exposed to air and moisture.
The ductility of steel allows it to be shaped by _____, as opposed to molding like concrete or cutting like wood and stone.
Rolling
The rolling process consists of repeatedly passing ingots of steel heated to ____F between large rollers until the intended shape is achieved.
2,200*F
____ _____ _____ is used for members that have a thin cross-section, such as floor and roof decking and wall studs. These studs can be used either for interior non-load bearing partitions or for exterior bearing walls.
Cold Rolled Steel (CRS)
Steel _____ as it is heated.
Expands
The __________ of steel strength at elevated temperatures is the characteristic most significant to the fire service.
Deterioration
______ ____ structural members with less mass require less heat to reach the failure temperature.
Unprotected Steel
Structure fires typically do not generate temperatures hot enough to melt steel; however, some fire do create temperatures in excess of ____F, which is hot enough to weaken steel to its yield point.
1,200*F
A steel column encased in 3” of concrete with a siliceous aggregate would have a fire resistance of ___ hours.
Four
___ ______ materials (SFRM) are efficient and inexpensive. The most commonly used are mineral fiber or expanded aggregate coatings such a vermiculite or perlite. The degree of fire resistance provided will depend on the material and the thickness of the application.
Spray-Applied Fire-Resistive Materials (SFRM)
Most fire-insulating materials can be applied in specific thicknesses to achieve different fire-resistance ratings. The applied fireproofing can vary from __ - __ inches to produce a fire-resistive rating of one to four hours.
7/8” - 1 7/8”
Cementitious materials have densities ranging from __ to __ pounds per cubic feet.
15 to 50 lb/ft*3
_____ can be used as an insulating material either in the form of flat boards or a plaster.
Gypsum
Intumescent coatings are applied as a paint. They have an applied thickness of __ to __ inches, which is less than the thickness of the spray-applied materials.
0.03 to 0.4 inches
A commonly used method of protecting a steel floor or roof assembly is the ____ _____. This is a suspended, insulating ceiling tile system that acts as a thermal barrier to protect the steel that supports the floor or ceiling above.
Membrane Ceiling
____ _____ provide a structural member that can carry loads across greater spans more economically than beams can.
Steel Trusses
*frequently used in 3D space frames known as delta trusses because they resemble the greek letter Delta
In basic steel trusses, open web joists are mass produced and are available with depths of up to __ feet and span up to ___ feet.
However, they are more frequently found with depths less than __ feet and spans of __ feet.
Depths up to 6’ and span up to 144’
Frequently depths less than 2’ and spans of 40’
Steel rigid-frame buildings with inclined (or gabled) roods are widely used for the construction of one-story industrial buildings, farm buildings, etc. The top of the rigid frame is known as the ____ and the points where the inclined members intersect the vertical members are known as the ____.
Crown ; Knees
Steel arches can be constructed to span distances in excess of ___ feet.
300
A property of a given column, known as its ____ ___, is used in combination with the condition of the column end to determine the load that can be safely supported without buckling.
Slenderness Ratio
The higher the numerical value of the slenderness ratio, the ___ likely it is that buckling will occur. In general, columns used for structural support in buildings should not have a slenderness ratio greater than ___.
More ; 120
Columns that are erected so they cannot rotate at their ends have ____ tendencies to buckle than columns that are free to rotate at their ends.
Fewer
A common floor design in steel-frame buildings uses a lightweight concrete with a minimum thickness of __ inches supported by corrugated steel decking. The corrugated steel is, in turn, supported by open-web steel joists.
2
Light-gauge steel joists are produced with depths of __ to __ inches and can be spaced __ to __ inches apart depending on the span and the load to be supported.
Depths of 6 to 12”
Spaced 16 to 48” apart
The fire resistance rating may be eliminated for roof construction located more than __ feet above the floor below for some occupancies.
20
The following 3 connection types increase the mass at the point of connection to make it the last item to fail within a structural system:
-Rigid Connections (used in the beam and girder type of frame)
-Steel Connections (steel webs known as gusset plates)
-Knee Joint between the roof and wall (gabled rigid-frame stuctures) **this connection has greater mass than other similar places
