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HOT > Ch. 21 Structural Collapse > Flashcards

Ch. 21 Structural Collapse Flashcards

1
Q

Structural collapse is ________ on the fireground.

A

One of the most feared occurrences

Large percentage of multiple-casualty incidents

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2
Q

Resistance to collapse per classes of construction:

A 
Most resistant to least resistant
Class 1 fireproof
Class 4 heavy timber
Class 3 ordinary/standard brick and wood joist
Class 5 wood-frame
Class 2 noncombustible
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3
Q

Which class of construction has:

  • up to 4 hr fire resistance
  • skeletal framework, poured concrete or steel I-beams
  • collapse is usually rather localized
  • load being supported generally remains in place
  • supposed to provide resistance to collapse to allow time for evacuation and fire control
A

Class 1 (greatest resistance to collapse)

1-4-3-5-2

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4
Q

Most severe collapse hazard in Class 1 bldgs is:

A

Poured-in-place concrete bldgs under construction

  • fire involves wooden formwork
  • pancake collapse
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5
Q

Second best construction type, as far as resistance to collapse is concerned:

A

Class 4, Heavy timber

  • generally 12 x 12 columns and brick walls
  • manual FFing long since shifted to exterior operations before danger of collapse
  • exception is bldg has been scene of numerous repeated fires in same area
  • advanced fires, apparatus removed (1 1/2 times collapse zone)
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6
Q

Third most collapse resistance:

A

Class 3, ordinary or standard brick and wood joist

  • more prone to burn through than collapse
  • flr/roof sheathing burn through long before floor joists fail
  • FFs could be working underneath, unaware due to hung ceilings or smoke
  • distinct danger=high floor loads and concentrated loads =roof-mounted AC
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7
Q

Fourth category in order or resistance to collapse is:

A

Class 5, wood frame

  • dimensional lumber more prone to deck burn through
  • only standard construction~doesn’t apply to lightweight truss-construction
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8
Q

Least resistant to collapse:

A

Class 2

  • large quantities of unprotected steel
  • steel expands –> 100 ft expands 9.5 in. at 1000F
  • at 1500F - lose its strength, will drop its load or twist/sag
  • steel cooled, contract back to 100 ft while retaining distorted shape
  • steel would shrink, end of beams no longer resting on original supports, collapse occurs
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9
Q

Hierarchy of structural components:

A

BCGBF

  • Bearing walls
  • Columns
  • Girders (support beams)
  • Beams and joists
  • Floor or roof decking
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10
Q

Protected steel or concrete supporting system resist _____ collapse rather well.
These are called _______ since most of their weight is carried in the frame or skeleton.

A

Total

Framed structures

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11
Q

Collapses that occur in framed structures are usually ________.

A

Very localized

only area between two supporting members

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12
Q

Structures with most of weight on bearing walls?

A

UNFRAMED structures

failure of vertical member more serious than horizontal

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13
Q

Wooden structural elements burn through at a rate of about:

A

1 in. for every 45 minutes of open-burning time

-fire attack standard 1 1/2 in. joist from TWO SIDES, burn through in less than 45 minutes

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14
Q

One of the most potentially dangerous situations is when columns support a ______ that carries the weights of upper-floor walls and floor joists when a __________ is removed to expand.

A

Girder

Ground floor wall

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15
Q

As little as ______ exerted laterally on a brick wall can topple it like a house of cards.

A

1 psi

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16
Q

Any location where _____ or _____ are stored demand tactics shift towards cautious, defensive operations.

A

Flammable gas

Explosives

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17
Q

Biggest offender at fire operations concerning overloading of floors and roofs?

A

Runoff from hose streams

- also heavy loads - plumbing supplies, snow, etc. with no fire

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18
Q

One factor FFs have direct control over (cause of collapse) is:

A

Cutting of structural members during overhaul

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19
Q

If forced to operate in area where structural weakness is suspected:

A

Use methods and tools that produce little or no impact load or vibration

  • use circular instead of axe or reciprocating
  • can be external sources
  • watch for elevated platforms
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20
Q

Examples of cause of collapse, miscellaneous

A
  • high wind
  • hose streams
  • age of bldg
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21
Q

Indicators of collapse

A

12 of them

  • each indicator separately might not raise SUFFICIENT ALARM
  • when viewed as whole, signs bldg is in danger
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22
Q

Number One indicator-occupancy by problem business

A

Plumbing supply, appliance dealership, printing shops (P’s)
Type of occupancy ALONE not reason to withdraw
-should trigger CAREFUL EXAMINATION for signs of collapse

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23
Q

Of all possible warning signs of collapse, only one more serious than truss construction

A

Structure that contains Explosives (rare and usually over before we arrive)
Number 2 collapse indicator

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24
Q

THE fire problem of 21st century

A

Fire in truss construction

-particle board I-beams deserve same technique

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25
Q

Prime indicators of bldg collapse (overloaded floors)

A
  • heavy equipment
  • water-absorbent stock
  • built up water
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26
Q

Consider withdrawing forces if:

A
  • Heavy fire obvious AND

- Not put out in 20 minutes

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27
Q

It is time to make decision about withdrawing forces when:

A

First members come out with low-pressure alarms ringing

Number 4 - fire more than 20 minutes

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28
Q

20 minutes rule begins

A
  • not on arrival BUT

- when fire reaches open, flaming stage OR flashover AND begins to attack structural elements

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29
Q

20 minute not for lightweight construction, instead:

A

5 minutes

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30
Q

Cracks could mean collapse is imminent or could have been there for 40 years

A

Pay special attention to cracks that are EXPANDING or LENGTHENING

  • indications of movement
  • prompt evac if extensive
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31
Q

Sign roof pulling away from wall

A

Relatively clean wood on ends of beams

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32
Q

One of LAST warning signs BEFORE collapse

A

OBVIOUS sagging of floors or roofs

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33
Q

Sponginess (roofs) calls for:

A

Further evaluation

-natural condition - inverted roof

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34
Q

Too late to reach safety

A

-obvious movement of floors, walls or roofs

35
Q

Sign of partial collapse in remote area of structure

A

Deep rumbling

36
Q

Plaster sliding off of walls and distortion of door and window frames

A 
Subtle movement of structure (plaster)
Result of being pushed over (doors/Windows)
-prevalent in class 5 construction
37
Q

____ is usual means of initiating the withdrawal.

Additional means of communicating for those not equipped or may not have heard is _____.

A

Radio

Turn all audible devices for 30 SECONDS

38
Q

Masonry walls weigh:

A

80-130 lbs. per cu. ft.

39
Q

Ladders or platforms must avoid positioning themselves:

A
  • Any closer to bldg horizontally than they are vertically

- from top of bldg to lowest part of their device

40
Q

Obvious instance where 1 1/2 times height of wall is too short:
(Ch. 21)

A

Collapse initiated by an Explosion

41
Q

“Rafters resting on a truss” collapse zone

A

2 1/2 times the height of the wall

42
Q

If 2 1/2 times collapse zone not possible then:

A
  • flanking positions off to sides of threatening wall OR

- position above wall, as in basket of elevating platform

43
Q

Beware of ____, ____, and ____ that could be brought down by primary collapse

A

Trees, telephone poles, overhead power lines

44
Q

(Elevating platform) When roofs collapse, huge fireball:

A

Some cases 50-60 ft high

-make sure platform isn’t perched directly over

45
Q

5 types of collapse

A

VASUP
V-shape - class 3/5 (overloaded, center support gone, burned away)
A-shape - common in explosions
Supported lean-to - supported each end
Unsupported lean-to - floor/roof joist dangling in mid-air
Pancake - appear to be unstable-not the case, lowest level examined, numerous rescues in class 3/5, locating victims somewhat simpler

46
Q

Individual voids formed by a series of strong objects AND are found in:

A

ANY type of collapse

47
Q

Appears unstable but is not the case:

A

Pancake

48
Q

This type of collapse has a severe danger of further collapse:

A

Unsupported lean-to

-because low end is totally unsupported

49
Q

First priority if FF is trapped or disabled in vicinity of fire:
(Collapse rescue ops, ch. 21)

A

Keep them from burning to death

  • one of first actions is to bring as many streams to bear in that area
  • nothing compares to Tower Ladder
50
Q

Other use of tower ladder at collapse rescue:

A

Boom as tie-off point for hoisting objects (full working load=1,000 lbs)

  • remove extra weight-jettisoning everything
  • brace boom with cribbing/planking
  • only as fixed anchor point
51
Q

The place for the best you’ve got available (rescuing downed members)

A

RIT, specially selected and equipped

-heavy rescue company, paramedic level firefighters

52
Q

5 stages of collapse rescue

A 
Recon - intelligence gathering
Surface victims (accounting for/removal)
Searching voids
Selected debris removal/tunneling
General debris removal
RS3G
53
Q

___ is search while ____ is actual rescue.

A

Void exploration

Selected debris removal

54
Q

During tunneling, ______ could increase chances of success.

A

Two or more approaches

55
Q

If threat of secondary collapse, several options:

A

Rope off area/deny access (not possible if survivors)
Shore up area
Tie off debris to substantial object
Pull debris over where it does no harm

56
Q

Most gruesome task yet

A

General debris removal

57
Q

Critical actions of first-alarm units:

A

Street management

Fire control

58
Q

Street management hampered by:

A

Scope of destruction
Crowd of spectators
Sheer volume of responding personnel

59
Q

First-alarm engine company PRIORITIES at collapse

A

Fire actively burning within rubble (highest priority).
Exposure protection (next).
Extinguishment of burning VEHICLES

60
Q

Collapse operations - first 4 engine ASSIGNMENTS

A

1st and 2nd engines = separate hydrants OUTSIDE the block on SEPARATE MAINS
3rd and 4th engines = similar positions at REAR of structure

61
Q

Frozen Zone for:

A
  • major incidents
  • no non-emergency vehicles
  • reduce vibration (secondary collapse)
  • preserve evidence
62
Q

During collapse operations, rotate personnel:

A

Every half hour or less (30 or less)

63
Q

Causes of collapse
AND
Collapse indicators

A

10
AND
12

64
Q

Building permit usually ensures that ______________ has at least reviewed the design for any obvious weaknesses.

A

An architect or structural engineer

65
Q

Lightweight steel bar joists can lose strength in 5-10 minutes of fire exposure. Thicker pieces take longer to heat up but when they _____________, their failure is just as assured as the lightweight ones.

A

Reach 1,500F

66
Q

Steel usually ____ prior to total failure.

A

Sags

67
Q

It’s ability to be readily cast in a mold and then bolted together in sections made it the first material to be used for _________ .

A 
Cast Iron
Prefabricated buildings (late 1800's)
68
Q

Cast iron has great compressive strength but almost no shear strength, therefore cast iron it was once a favorite material for ______ but unsuitable for _____.

A

Columns and prefab walls

Beams

69
Q

Overloading of floors
Large quantities of material that absorb water, such as ____, _____, and _____. Two effects that threaten collapse: _______ and _______.

A

Newsprint, baled rags, baled cotton

First is weight (absorb their full weight in water)
Second effect is as they absorb water, they swell

70
Q

Collapse rescue operations

SEARCH team should bring

A

Spare SCBA or RIT-pak for each victim

At least one member of SEARCH should be EMT

71
Q

Best chances of locating victim occur when you know which area to start looking. This is part of:

A

Recon or intelligence gathering

72
Q

One difficulty in controlling utilities at collapse scenes is:

A

Controls may be buried under debris

73
Q

Surface victims (2) can be done simultaneous with:

A

Recon (1)
AND
Searching voids (3)

74
Q

Done to take advantage of natural openings remaining in the debris, LEAST labor and time consuming, victims with greatest chance of survival

A

Search of voids

75
Q 
Immediately designate an officer to:
Keep track of who leaves or are removed
-name and where located.
-if time permits, escape route.
Noting any injuries.
If victims transported, what hospital.
A

Victim Tracking Coordinator

76
Q

No matter what type of building is involved, ________ such as ____ and _____ must be forbidden at this stage. Although a MANUAL operation is time consuming, it is _____________.

A

Large, power demolition equipment
-Backhoes and cranes

Necessary as long as you suspect there are survivors

77
Q

Once you get close to the victim, all work should ______________.

A

Proceed with only hand-powered tools, unless object and victim are visibly clear and no injury is likely.

78
Q

Tools that produce no _______ are preferable. Tools that perform a task _______________ are usually preferable to those that do.

A

Exhaust fumes

Without producing showers of sparks

79
Q

Once all of the live victims have been removed, the ______________.

A

Selected debris removal operation should cease

80
Q

This task should also be performed at any fast-moving fire that results in early collapse since there may be persons present who haven’t yet been missed

A

General debris removal

81
Q

Street Management-
It is up to the _____________ of each and every vehicle approaching the scene to take the proper actions to ensure continued smooth access to the site.

A

Officer AND driver

82
Q

_______ should also be kept away from the front of the building. The positions in front of the collapsed structure should be taken by __________. In close proximity but not directly in front of the building should be ___________.

A

Aerial ladders

Elevating platforms (telescoping type-tower ladders)

One or more heavy-rescue apparatus and /or specialized collapse shoring vehicles

83
Q

The ________________ will likely begin triage and initial treatment. Position them ___________, __________ but ___________ and _________.

A

First two or so ambulances

In proximity to the structure
Visible from the scene
Out of way of rescue/firefighting operations
Out of secondary collapse zone

HOT (22 decks)

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