Dunn Collapse Book

Question 1

Masonry Wall Collapse Types

Answer 1

• 90 degree angle collapse is the most common type of masonry wall failure
• Curtain Fall Collapse - often occurs w/ brick veneer, brick cavity or masonry backed stone wall
• Inward-Outward collapse. The Top falls Inward, the Bottom falls Outward

Question 2

Masonry Wall Collapse Zone

Answer 2

• Generally, the collapse zone is a distance equal to the height of the wall
• May be increased to 1.5 to 2x the height of the wall if:
  
  1. A truss roof triggers the wall collapse
  2. An explosion triggers the wall collapse
  3. If ordered by the IC

Question 3

Parapet Wall

Answer 3

• A vertical cantilever wall

- It is unstable because it is freestanding

Question 4

Facade

Answer 4

• Indicates the front of the building

- Can include a parapet wall, marquee, canopy, or cornice

Question 5

Marquee

Answer 5

• A cantilever beam supported at only one end that is connected to a parapet wall
• b/c it is hollow, it is like a swimming pool hanging off the front of the building

Question 6

Canopy

Answer 6

• A cantilever beam that is lightweight and constructed of small pieces of wood or metal
• A canopy is combustible
• A canopy is more of a collapse danger than a marquee
• Most dangerous type is a metal or wood shed suspended over a truck loading area
• FF’s should not stretch hose lines or place ladders on top of a canopy roof

Question 7

Cornice

Answer 7

• Decorative horizontal overhang, projecting outward along the top wall of a building
• Cornices burn and spread fire
• May be constructed of wood or combustible plastic

Question 8

Wall Attachments

Answer 8

• Parapet Wall, Marquee, Canopy, Cornice
• The area beneath a Marquee, Canopy, or Cornice is considered to be inside the building
• If an order is given to withdraw from a building, FF’s must be withdrawn from beneath the Marquee, Canopy, and Cornice as well.

Question 9

Hierarchy of Collapse

Answer 9

1. Bearing Wall - Most Serious
2. Column
3. Girder
4. Beams (Floor & Roof)
5. Deck - Least Serious

Question 10

Attached Two-family houses

Answer 10

• Attached two-family houses w/ a plasterboard or masonry firewall between the houses MUST be considered ONE STRUCTURE
• When ONE HALF of the attached structure becomes unstable and in danger of collapse during a fire, the ENTIRE structure is in danger. Occupants and FF’s MUST be withdrawn from BOTH SECTIONS

Question 11

Steel Characteristics

Answer 11

1100ºF = Failure temperature of steel -will lose 40% of load carrying capacity