In collapse patterns, the pattern where floor and roof assemblies collapse on both sides of a load-bearing center wall is called what?

• A. Pancake
• B. Lean-to
• C. V
• D. A frame

Answer: (D)

This pattern is identified by symmetry around a central load-bearing wall. When the floor and roof assemblies fail on both sides of that center wall, they hinge and collapse toward the wall, creating an A-shaped debris profile. The center wall often remains standing, while the sides drop inward, forming triangular sections on both sides.

Understanding this helps you anticipate that the most dangerous area is near and under the collapsed roof lines directly adjacent to the center wall, so approach from the sides and establish a safe collapse zone. This differs from a pancake collapse (floors pile straight down without a central hinge), a lean-to (collapse on one side), or a V-shaped pattern (two-sided collapse away from the center but not forming an A around a central wall).