The Truss Failure Theory
Theory Invented to Sidestep Problems With Column Failure Theory
The FEMA-endorsed truss failure theory purports to explain the collapses of the Twin Towers with an account of a series of events that supposedly initiated the collapses. It was apparently invented to address the most obvious shortcoming of the column failure theory: that the temperatures of the fires were not nearly high enough to weaken the columns enough to cause them to fail.
NOVA and Dr. Eagar Team Up to Sell the Truss Theory
One of the principal promoters of the truss theory is Dr. Thomas Eagar, a professor of materials engineering at MIT. He co-authored an article in JOM and gave an interview to NOVA , which appears on their website. Though he probably can't claim credit for the truss theory, he might be credited for the zipper theory, which purports to explain the failure of all of the trusses on a floor in quick succession:
The graphics for the NOVA article are interesting for what they leave out.
The animation, which shows the beginning of the unzipping chain reaction,
doesn't show the cross trusses, which ran perpendicular to the falling trusses.
- The animation implies that the floors simply rested on the trusses. In fact the tops of the trusses were bolted to the corrugated steel pans underlaying the concrete floor slabs.
The core is depicted as a stack of slabs, rather than a bundle of columns.
How interesting that an article purporting to explain the collapses
omits the most basic element of the tower's
The building that the plane is flying into at the same roll angle as the
North Tower hit has prominent horizontal ribs and barely visible vertical lines.
So much the better for pancaking!
- The size of the plane relative to the tower would be correct if the plane were a 747, which has over twice the mass of the 767-200 thought to have hit the tower.
Also absent from the article are any actual pictures of the buildings being leveled. How thoughtful of them to replace those unpleasant exploding clouds of dust with nice clean computer animations.
Having been promoted by a trusted popular science television program, the truss theory is accepted by the vast majority of Americans who have bothered to wonder about how the towers collapsed, despite more and less obvious flaws in the theory.