06 Wood Floor Collapse

Question 1

What is the leading cause of FF death by collapse?

Answer 1

Floor failure

Question 2

The ________________ means, the destructiveness of a collapse depends on the first structure to fail and where this structure is positioned within the building supporting system.

Answer 2

Structural Hierarchy Effect

Question 3

What floor construction is considered lightweight truss flooring?

Answer 3

1. Wood truss
2. Wood laminated I-Beam
3. Lightweight cold-formed steel C-floor beams
4. Open-web bar joists

Question 4

What are the three ways all floors fail during a fire?

Answer 4

1. The floor deck collapse
2. Floor beam collapse
3. A multilevel floor collapse describes a progressive floor failure. Here a floor collapse triggers the subsequent collapse of floors below and of one or more enclosing walls.

Question 5

What happens in a floor deck collapse?

Answer 5

Only the wood deck may burn through and collapse, leaving the supporting joists intact.

Question 6

What happens in a floor beam collapse?

Answer 6

Where several floor joists fail, causing a localized failure of a section of floor within a room. This is a more deadly collapse than floor deck collapse.

Question 7

What happens in a multilevel floor collapse?

Answer 7

A multilevel floor collapse describes a progressive floor failure. Here a floor collapse triggers the subsequent collapse of floors below and of one or more enclosing walls.

Question 8

When does a multilevel floor collapse most often happen?

Answer 8

In burning buildings that have columns and girders supporting floors.

Question 9

Strategies and tactics that can protect FFs from the three types of floor collapse:

Answer 9

1. Floor deck collapse: Sound the floor
2. Floor beam collapse: Use the reach of the hose stream
3. Multi-Level floor collapse: Withdraw FFs

Question 10

A floor can receive a 1-hour rating if it withstands the test fire for one hour without the top surface exceeding an average rise in temp of __________________________.

Answer 10

250 to 325 degrees Fahrenheit

Question 11

Reasons why fire-resistance ratings have little significance with the fire service:

Answer 11

1. There is no test for collapse resistance
2. Length: a 60-foot section will fail sooner than the tested 20-foot
3. Renovations to a floor may negate the fire-resistive rating
4. Workmanship of the test sample vs actual floor
5. Changes of the construction design
6. Requirements for installation are not always followed
7. Real fire may reach higher temperatures than the test fire

Question 12

There are three recurring factors that contribute to floor collapse in a burning building:

Answer 12

1. Vacant Buildings
2. Renovated Buildings
3. Buildings Overloaded with heavy machinery or dense content

Question 13

Vacant Buildings

Answer 13

Maintenance stops and the building deteriorates. Floors weaken as they are exposed to the freeze-thaw cycle of weather changes.

Question 14

Renovated Buildings

Answer 14

Can have floor construction that is not as stable as the older floor. Floor supports (supporting walls or columns) can be removed or changed to lightweight or substandard construction.

Question 15

Overloading of Floors

Answer 15

Merchandise that can absorb water or heavy machinery make floors vulnerable to failure during a fire

Question 16

There are three stages of a fire:

Answer 16

1. The growth stage
2. The fully developed stage after flashover
3. The decay stage (after most fuel is consumed or extinguished)

Question 17

The most dangerous time for floor collapse is?

Answer 17

During the end of the fire, in the decay stage, after it has been extinguished.

Question 18

At most floor failures there are no:

Answer 18

1. Warning signs
2. No time to act and withdraw FFs
3. No satisfactory explanation of the incident

Question 19

A ______________ must be considered for wall collapse after the floors fail.

Answer 19

Collapse Zone