Fire Officer Tactics: Structural Collapse (Ch 21)

Question 1

Collapse risk by building type (lowest to highest)

Answer 1

• Class I
• Class IV (heavy timber)
• Class III (ordinary)
• Class V
• Class II

Question 2

Hierarchy of structural components (most to least important)

Answer 2

1. Bearing walls
2. Columns
3. Girders
4. Beams and Joists
5. Floor or roof decking

Question 3

Causes of collapse

Answer 3

• Structural weakness due to faults in design, poor workmanship, improper renovations
• Fire damage to wooden structural members
• Heating of unprotected steel
• Failure of highly heated cast-iron columns
• Explosions of fuels, explosives, or backdraft
• Overloading of floor and expansion of absorbent materials
• Overloading of floors and roof
• Cutting or removing structural members during overhaul
• Vibration and impact load
• Misc (winds, flooding, damaged water mains)

Question 4

Collapse indicators

Answer 4

• Occupancy by problem businesses
• Construction
• Overloaded floors
• Heavy fire burning for > 20 minutes
• No appreciable runoff
• Cracks or bulges in walls
• Water or smoke seeping through solid brick wall
• Roof pulling away from wall
• Roof sagging or feeling abnormally soft/spongy
• Any obvious movement of floors, walls, or roofs
• Noises
• Plaster sliding off walls or plater dust in air

Question 5

Types of collapse

Answer 5

• V-shape
• A-frame
• Supported lean-to
• Unsupported lean-to (cantilever)
• Pancake

Question 6

V-shaped collapse

Answer 6

• Victims on collapse floor not close to center thrown towards center along with debris
• Victims below collapse along perimeters likely to survive

Question 7

V-shape collapse

Answer 7

• Usually occur in Class 3 or 5 buildings
• Least chance of survival directly below collapse
• Highest near the walls

Question 8

Supported lean-to collapse

Answer 8

• Good chance of survival if on lower floor near remaining wall
• People on falling floor also if not crushed by by heavy objects
• Worst near failed wall below collapse

Question 9

Pancake collapse

Answer 9

• Numerous rescues from class 3 and 5 buildings
• Survival depends on strong objects nearby that create individual voids
• Voids difficult to locate

Question 10

5 stages of collapse rescue plan

Answer 10

1. Recon
2. Accounting for and removal of surface victims
3. Searching voids
4. Selected debris removal and tunneling
5. General debris removal

Question 11

Safety precautions during collapse operations

Answer 11

• Shut down all utilities
• Monitor atmosphere
• Prohibit smoking
• Remove all nonessential personnel
• Control spread of fire if present
• Prepare for fire if it isn’t already present
• Maintain constant watch of weakened walls, floors, bld. components (use transit)
• Eliminate vibrations (highways, rail, apparatus)
• Do not cut or remove major supports
• If must cut support, brace and shore, prepare for secondary collapse, remove everyone else
• Frequent rotations (every 30 min or less)
• Maintain communications (between rescuers and with victims)
• Seek expert assistance