The Pancake, or Truss Failure, Theory

The truss failure, or floor pancake theory, was

• Endorsed by ASCE/FEMA Building Performance Study, May, 2002
• Popularized by NOVA/Discovery Channel, Professor Thomas Eagar

Since the lightweight trusses undergirding the floor slabs were not visible from the outside, it could be imagined that they became very hot, and softened enough to succumb to their loads.

The failure of some of these trusses would be the first in a rapidly cascading chain-reaction of events resulting in the total destruction of the buildings.