In Reply to: It DID withstand the hits sir. posted by JRV on September 11, 2001 at 23:34:02:
From the reports I was reading yesterday it seemed the building structure was compromised from the direct impact. Load bearing members shifting until collapse. I saw no evidence of this.
But PBS did reiterate it was designed to take an impact.
PSB did an excellent piece with a couple doc's in structure engineering from berkeley giving there 2 cents. basically, the steel was annhealed from the intense heat and lost all (most) load carrying capability. jet fuel burns 300-500 degrees hotter than standard combustables and the orginal design is based on a building fire- not jet fuel.
but the structure-other then the hole- bearly fliched. The damn plane went through it. with no fire, no doubt it would have been relativily easy to repair. 3-5 floors would be gutted and repaired within (from the outside appearance) a month. Inside would have been slower.