Which collapse pattern is formed when single or multiple floors and/or roof collapse, resulting in a layering effect and difficult access in concrete structures?

• A. V shaped
• B. Cantilever
• C. Pancake collapse
• D. A-frame collapse

Answer: (C)

Pancake collapse occurs when floor slabs and the roof drop straight down and settle onto the level below, creating multiple stacked layers of debris. In concrete structures this produces a layering effect—think of several horizontal slabs piled on top of one another—that makes access and search difficult because there are many parallel levels with limited or unstable paths between them. This pattern is distinct from other shapes: a V-shaped collapse forms a triangular wedge with a pointed bottom, a cantilever collapse involves outward tipping of a portion still attached at one end, and an A-frame collapse creates a triangular, upright wedge. The pancake configuration specifically describes the horizontal stacking of floors and roofs, which is why it’s the correct choice for a layered, hard-to-reach collapse in concrete structures.