Some Misunderstandings Related to WTC Collapse Analysis

[Tony Szamboti]

Jeffrey, As I understand your sketch entitled Top Drop Cartoon, the load supported by the compromised core columns was slowly transferred to the perimeter columns via the hat trusses. As the perimeter column exceeded their designed load capacity, they began to buckle and slip pulling the core columns down. The core detaches from the hat trusses. After that I am a little vague. But somehow this leads to a cascading collapse which Major Tom calls ROOSD, which stands for Runaway Open Office Space Destruction. Am I correct in interpreting your cartoon?

Basically you are getting the gist of the diagram. It's meant to show what happens as the core columns are weakened. When the lose capacity the 12 floors of the core ... and there were only 2 elevator chafts in the core at that height... were hanging from the hat truss. And this include part of the weight of the floors outside the core as the 24 perimeter core columns support about 45% of the outside the core floor loads. When the core lost capacity all of the loads were moved over to the facade columns which buckled and in so doing there was lateral translation and the facades slipped past each other 2 side passed outside and 2 inside. But surely the facade wasn't able to carry the floor loads alone including those inside the core up there. This mass.. became the ROOSD mass driving through the inside of the tower down to the ground.

This disagrees with the NIST analysis I take it--although the details escape me? And has this thesis been discussed in the requisite journals? I gotta say that anon posters over at randi don't cut it when it gets down to it. OK, now I will stare at the diagram some more.

Jeffrey's scenario in his cartoon has never been proposed by anyone who has published anything because it is fully impossible and a certain fiction, as the hat truss outriggers were not capable of transferring 12 stories of core load to the perimeter (the exterior columns that Jeffrey calls the façade).

The outriggers were A-frames meant to transfer antenna wind loads to the perimeter to gain a larger lever arm than just that provided by the core. They were about 10% of what would have been needed to transfer 12 stories of core load to the perimeter and would have failed in bending immediately when the core load was applied to them.

The truth is the outriggers did fail when the core load was applied to them and that is why the interior did go down first, as evidenced by the antenna drop before the exterior roofline, which had to wait for the core to pull the perimeter columns in at the 98th floor causing them to buckle and fail. It wasn't because they were overloaded from the top the way Jeffrey wants to say. That was impossible and it can be guaranteed that Jeffrey has no analysis showing the outriggers could take and transfer the core load he claims.

Additionally, the core load was not capable of overloading the perimeter even if it could be transferred by the outriggers. The perimeter columns only had 20% of their capacity used and they supported at least 50% of the building load. So if the core load was placed on them they would only be loaded to 40% of their capacity. Jeffrey's cartoon has no basis in reality and was certainly not the cause of failure for the perimeter. They did buckle but it was not due to overloading from the top as he claims. It was due to pull in creating extreme eccentricity (which columns cannot tolerate) by the failed and falling core.