Reply To: Engineering Prof releases draft report on 9/11 collapse of WTC Bldg 7 in NYC


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#46919
Gerry
Guest

And there you go blaming the truss seats. The concrete and pan with rebar above the trusses was stronger than them and sagging trusses in the towers do not have the ability to pull the perimeter columns in as observed. In the transverse areas of the towers the long span floor truss system was not connected to the core, but to the short span transfer truss.

This indicates that for the perimeter coolumns to be pulled in on the South face of the Borth tower some 5 – 10 minutes before initiation would require a failure within the core area, thus causing the perimeters to be pulled in. In NIST’s tower analysis the added an imaginary 5kip lateral force to the perimeter column to get them to bend in as observed, for the very reason that the sagging trusses could not do it.

They also omitted bridging trusses in all the one way zones throughout their full tower model along with anchor straps and shear studs along with other reinforcement.

You can observe that the antenna of the north tower tilts before the roofline moves at initiation, confirming a failure initiating event initially confined to the core, not yet having transmitted through the outrigger truss above floor 107 that held the antenna support steels.

The North tower collapsed in about 13.8s total which equates to around 2/3 freefall, total freefall being approcx 9.2s for 1365ft. Still way too fast.

Maybe you should go get that SE to help you out a bit here.