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BC 3rd > Ch. 9 Steel Construction > Flashcards

Ch. 9 Steel Construction Flashcards

1
Q

P. 258

BEHAVIOR of steel under fire conditions depends on: (2)

A
  • the MASS of steel

- degree of RESISTANCE

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2
Q

PROTECTION of steel depends on: (4)

A
  • INTEGRITY of installation
  • protection METHODS
  • MAINTENANCE
  • FAILURE POINTS
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3
Q

Basic properties of steel (4)

A

STRONGEST of bldg material
NON-ROTTING, resists aging, dimensionally stable
Consistent QUALITY
Relatively INEXPENSIVE (strength/forms enable to be used in smaller quantities)

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4
Q

Steel is basically an alloy of:

A

Iron and carbon

  • structural steel less than 3/10 of 1% carbon*
  • cast iron = 3-4% carbon
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5
Q

Composition of steel can be altered:
Molybdenum for:
Vanadium for:
Manganese for:

A

Molybdenum - strength
Vanadium - strength/toughness
Manganese - resistance to abrasion
movama

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5
Q

Lower carbon content of steel results in material that is ____ rather than _____.

A

Ductile
Brittle
-ductile = enables steel to be rolled into variety of shapes
Rolling ingots at 2,200F between rollers

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7
Q

The _____ of steel also allows it to be rolled in the cold state. Known as CRS.

A

Ductility

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8
Q

CRS can be used for _______ partitions or _______ walls.

A

Interior non-load bearing

Exterior bearing

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9
Q

Steels with _____ yield points have _____ ductility.

A

High

Less

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10
Q

Very common steel, A36, has yield point of ______.

A

36,000 psi
yield point reached-pronounced deformation
Breaks at “Ultimate Stress”

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11
Q

Steel possesses 2 inherent disadvantages:

A

Tendency to RUST (exposed to air and moisture)

Loss of STRENGTH (exposed to heat)

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12
Q

Steel protected by rust: (3)

A

Paint
Coating (zinc and aluminum)
Produced using ingredients that resist rust (stainless)

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13
Q

To the fire service, ______________ is its most significant characteristic.

A

Deterioration of the strength of steel at elevated temperatures

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14
Q

Fire typically encountered by firefighters do NOT ___________. However, they DO create enough heat to ____________, resulting in _________.

A

Create temperatures hot enough to MELT steel
Greatly weaken steel
Structural failure

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15
Q

At 1,000F, yield point of steel has dropped from 36,000 psi to _______. At 1,200F, it has dropped to ______.

A

18,000 psi.

10,000 psi

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16
Q

Because temperatures in excess of _______ are regularly encountered in fire, failure of unprotected steel, to a greater or lesser degree, _________.

A

1,200F.

Can be anticipated

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16
Q

Speed at which unprotected steel fails depends on (5)

A 
MASS
INTENSITY of fire
LOAD supported
Type of CONNECTIONS
Type of STEEL
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17
Q

Density of steel

A

490 lbs per cu. ft.

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18
Q

Unprotected steel; members such as ____ and ____ can be expected to fail EARLY

A

Bar joists

Slender trusses

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19
Q

BC 20 ft beam heated from 70-1,000F will elongate _____

A
  1. 4 inches

* HOT 100 ft @1000F = 9 1/2 in. lengthwise*

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20
Q

Heating of steel _____ occur in a uniform manner

A

DOES NOT

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21
Q

Both yielding and thermal expansion take place simultaneously; however the tendency for steel to _____, and therefore ______ is the MORE SIGNIFICANT concern in most fire situations.

A

Yield

Bend or buckle

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22
Q

Cast iron tends to fail by _______________. (Columns and staircases)

A

Fracturing from impact loading

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23
Q

Cast Iron; Firefighter need to be concerned with _____________. It may be a failure of _________.

A

The way the cast iron fronts are ATTACHED to the structures.

These attachment points

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24
Q

Steel shapes can be used to construct a frame of:

A

Columns
Beams
Girders

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25
Q

Large horizontal member used to support joists and beams at their isolated points along their length.

A

Girder

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26
Q

Because steel is _____ but very _____, it is not efficient to use it in the form of _____________ as is done with wood or concrete.

A

Strong
Dense
Solid slabs or panels

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27
Q

Beams and columns connected by (2)

A

Bolting or welding

riveting not practical today

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28
Q

Connections are ________.

Connection of a beam to a column not only _____ but also ________.

A

Very important

Transfers the load
Determines the rigidity of the basic structure

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29
Q

Beam and GIRDER frames can be classified as: (3)

A

Rigid
Simple
Semi-rigid

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30
Q 
Beam and Girder Frame;
Not completely rigid: enough rigidity for some diagonal support
Shear panels or diagonal bracing
Shear panels-reinforced walls
Shear walls-continuous
A

Semi-rigid

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31
Q 
Beam and Girder Frame;
Support a vertical force
Degree of angular change CAN OCCUR if no diagonal bracing
Supported by masonry wall
Also examples of simply supported
A

Simple Frame

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32
Q

Beam and Girder frame;
Connections resist bending forces
No change in angle

A

Rigid frame

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33
Q

Two commonly encountered applications of the basic steel truss are the:

A 
Open web joist (Lightweight steel truss).
Joist girder (Heavy steel truss-take place of beams)

steel truss-opens her web, find the girder

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34
Q

Open web TRUSS constructed entirely of steel, with steel bars used as the web members (round bar used)

A

Bar Joist

  • Closely spaced configurations
  • Supported on masonry wall
35
Q

Steel trusses frequently used in _______, in which case they are known as _________ because __________.

A

Three-dimensional space frames
Delta trusses
They resemble greek letter Delta

36
Q 
Open web joist
Depths up to \_\_\_\_
Spans up to \_\_\_\_
FREQUENTLY FOUND
Depths \_\_\_\_\_
Spans \_\_\_\_\_
A

6 ft, 144 ft.

Less than 2 ft, 40 ft

37
Q

Open web joist made of:

A

2 angles.
2 bars. OR
T-shaped member

38
Q

Open Web Joists.

Diagonals members made from:

A

Flat bars welded to top/bottom OR

Continuous round bar bent back and forth bar joist

39
Q

Gable roof rigid-frame structures must be ___________ to prevent deflections in the direction _______ to the plane of the frame sections.

A

Braced diagonally

Perpendicular

40
Q

Gable roof rigid frame - diagonal bracing accomplished by:

A

Diagonal cross-members: in the plane of the roof AND

In the vertical plane of the walls

41
Q

Steel rigid frames (with inclined Gabled roofs) usually are used for spans:

A

40-200 ft

42
Q

Top of a rigid frame is the ____ and the points where inclined members intersect the vertical members are known as the _____.

A

Crown
Knees
rigid with no rotation

43
Q

_________ used to support roofs on buildings where large unobstructed floors are needed, includes gymnasiums and convention halls.

A

Steel arches

44
Q

Steel arches can be constructed to span distances _______.

A

In excess of 300 feet

45
Q

Two types of steel arches:

A

Girder arches

Truss arches

46
Q

_______ constructed as a solid arch that may be built up from angles and webs with a cross section similar to that of a beam.

A

Girder arch (SOLID)

47
Q

____ is built using truss shapes. May have ______, which allows for slight movement between the two halves due to _____ or _____.

A

Truss arch
Pin connections
Settling or temperature change

48
Q

Drawing steel through a die to produce wire greatly _________ the strength of steel. It is possible to produce wire for use in bridge cables with strengths as high as ________ psi.

A

Increase.

300,000

49
Q

Cables: such slender shapes are subject to _______ and therefore limited to the support of ________ forces.

A

Buckling

Tension

50
Q

Suspension systems can provide large unobstructed areas similar to arches without ________________.

A

The reduction in vertical clearance at the sides of the building
(Cantilever roof-suspension)

51
Q

Possibility of buckling is _______ with steel columns than with columns made of other materials.

A

Greater

-because of small cross-section compared to length

52
Q

Most common cross-sections of columns are: (3)

A

Hollow cylinder
Rectangular tube
Wide flange

53
Q

Possibility of buckling in an individual column is a function of: (3)

A

It’s length
It’s cross-section
Method by which its supported at top and bottom

54
Q

_______ is a number that compares the unbraced length of a column to the shape and area of its cross-section. The higher the numerical value, the ________ likely it is that buckling will occur.

A

Slenderness ratio.
More
womens size increases, she is going to buckle

55
Q

Columns used for structural support should NOT have a slenderness ratio greater than _____.

A

120

56
Q

Slenderness ratio can be modified by the manner:

A

In which the ends are attached to the rest of the structure

57
Q

Very common floor design in steel frame bldgs uses a lightweight concrete with a minimum thickness of ______ supported by corrugated steel decking.
Corrugated steel, in turn, is supported by ___________.
Joists supported by _____ or ______.

A

2 in.

Open-web steel joists.

Steel beams or masonry wall

58
Q

Where floor loads or spans dictate, _____ are used to support flooring instead of lighter open-web joists. _________ are also sometimes used.

A

Steel beams

Light gauge steel joists

59
Q

Steel joists produced with depths of _______ and can be spaced ______ apart.

A

6 to 12 in.

16 to 48 inches apart

60
Q

P. 270 Steel structures

Two factors that affect possible failure:

A

Mass of the steel members
Type of structural connection
-Rigid-intact
-Simple-fail

61
Q

Steel connections, both in case of rigid, with beam and girder and heavy trusses, use ______, which _________ the connection, _______ the steel mass and _______ it’s possibility of failure.

A

Gusset plates
Strengthen
Increases
Decreases

62
Q

In gabled rigid-frames structures, the ______ between the roof and wall will be the strongest/last part to fail.

A

Knee joints

63
Q

Large beam and girder frame made of repeating sections, adjacent sections tend to be mutually supporting. Provides _____.

A

Degree of redundancy

64
Q

Steel column encased in _______ of concrete with a siliceous aggregate would have a fire resistance of ______.

A

3 inches
4 hours
increases weight and cost

65
Q

Most commonly used insulating materials are ______, _____, and _______. Some of these insulating materials are applied by spraying and are known collectively as __________________.

A

Gypsum
Spray-applied materials
Intumescent coatings
Spray-applied Fire Resistant Materials (SFRMs)

66
Q

Gypsum can be used as an insulating material either in the form of ________ or _________.

A

Flat boards

Plaster

67
Q

Two types of gypsum board:

A 
Regular
Type X (additives)
68
Q

Gypsum consists of approx. _________ water.

A

21%

69
Q

Gypsum can be used to protect both _____ and _______, providing fire resistance ratings from _________. Gypsum board is used in ___________ to attain higher fire resistance ratings.

A

Columns
Beams

1-4 hours
Multiple layers

70
Q

Spray-applied Fire-Resistive Materials (SFRMs) are _____ and _______. The most commonly used SFRMs are _____ or ______ such as ____ and _____.

A

Efficient
Inexpensive

Mineral fiber or expanded aggregate coatings
Vermiculite
Perlite

71
Q

SFRMs - Degree of fire resistance depends not only on: (2)

A

Material

But also thickness

72
Q

SFRM.

Applied fireproofing can vary from ____ to _____ to produce a fire resistive rating of __________.

A

7/8-1 7/8 inches

1-4 hours

73
Q

SFRMs - relatively soft and easily dislodged, not suitable for exterior use

A

Low-density mineral fiber materials

74
Q

SFRMs - densities greater than 20 lb/cu. ft., can endure conditions of limited weather exposure and higher humidities such as parking facilities

A

“More durable”

75
Q

SFRMs - use magnesium oxychloride have densities ranging from 40-80 lb/cu. ft.

A

High-density

76
Q

SFRMs cementitious - densities of _______

A

15-50 lb/cu. ft.

77
Q

Intumescent coatings will __________ when exposed to the heat of a fire. An intumescent coating will _____________ when heated, and will expand ________ it’s original volume.

A

Undergo a chemical reaction
Char, foam AND expand
15 to 30 times

78
Q

Intumescent coating applied thickness of ________, which is _____ than the thickness of spray applied materials. Because they have appearance of paint, ______ to visually establish fire-resistive coating has been applied.

A

.03 - .4 inches
Less

Difficult

79
Q

Intumescent and mastic are relatively _______ but they are frequently the most ___________.

A

Expensive

Aesthetically pleasing

80
Q

VERY COMMONLY used method of protecting steel floor or roof assembly is ____________.

A

Membrane ceiling

81
Q

The most common method is to use ______ in a __________ suspended by ______.

A

Mineral tiles
Steel framework
Wires

82
Q

FREQUENTLY used in systems that make use of __________.
Use of membrane ceiling can provide a floor and ceiling assembly or a ceiling and roof assembly with a fire rating of ______.

A

Open web joists

1 to 3 hours

83
Q

Ceiling materials are _______ rated independently. A ceiling is always rated as part of a ___________ assembly, so it is not accurate to speak of the fire resistance of a ceiling alone.

A

Never

Floor and ceiling

84
Q

_______ is one of the two methods of providing fire-resistive construction, such as Type ___, ____ and _____. The other method is ________.

A

Protected steel
IA, IB, IIA

Reinforced concrete

85
Q

Examples of permit reductions:

A

Eliminating fire-resistance of roof construction if ceiling is MORE THAN 20 ft above floor.
Reduction of required fire resistance when an automatic sprinkler system

BC 3rd (9 decks)

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