reply to post by hackbart
Looks like a window blowing out, due to over pressure, to me.
This would happen as the building collapsed and the internal volume of the building decreases.
Originally posted by JustInCase101
reply to post by 911fnord
p.s no one died in wtc7 so who cares no one lol.
edited for ps
[edit on 1-1-2009 by JustInCase101]
The design was a "tube in a tube" construction where the steel reinforced, cast concrete interior tube, was surrounded with a structural steel framework configured as another tube with the load bearing capacity bias towards the perimeter wall with the core acting to reduce deformation of the steel structure maximizing its load bearing capacity. All steel structures with the proportions of the WTC towers have inherent problems with flex and torsion. Distribution of gravity loads was; perimeter walls 50%, interior core columns 30% core 20%.