A pancake collapse is a progressive collapse in which the primary structural element fails and then results in the failure of adjoining structural elements and in turn causes further structural failure.
For example a high rise building collapsing with the floors above it collapsing onto the other floors until it falls down completely.
Pancake collapses are sort of like a domino effect when they fall.
Most pancake collapses occur after major earthquakes when earthquake tremors damage load bearing structures in a building or bridge.
Pancake collapses occur when pillars and other supporting structures in a multi-story building fail as a result of an earthquake or poor construction, causing floors to fall on top of each other.
In some cases, whole buildings can collapse vertically in a few seconds, making it difficult for people inside to escape.
Other types of collapses include.
90° angle collapse. This is the most common type of structural collapse. It is similar to a falling tree.
Curtain-fall collapse. This type of collapse generally occurs with a masonry wall.
Inward/outward collapse. A wall leaning inward may not necessarily fall inward.
Lower floors may have more substantial structural elements, such as reinforced columns and beams, which can provide additional support during a collapse.
Furthermore, being closer to the ground floor can facilitate a quicker evacuation, especially if exits are relatively accessible.
The Surfside Condo Collapse that occurred on June 24th 2021 is an example of a pancake collapse.