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Creative Speculation
In reply to the discussion: Cutter Charges in the North Tower... [View all]hack89
(39,181 posts)37. Too many damaged columns further weakened by fire
        the towers were hit by fully loaded 767s at top speed. They had to have inflected significant damage to some core columns. Which meant you have fewer columns supporting the same amount of weight. You then heat those columns until they are weakened - not melted but weakened. The fires were plenty hot and it doesn't take that long before the weight carrying capacity of the columns were degraded.
Once the first column sagged it was all over.  All that massive PE was instantly converted to KE and the collapsed began.  The lower floors were not designed to withstand such massive dynamic loads.
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        so you can tell from that picture that the puff is "exiting out of a single window"?
        zappaman
        Jan 2012
        #4
      
        
        But you haven't found it yet: keep looking. That link proves NOTHING. n/t.
        apocalypsehow
        Jun 2012
        #71
      
        
        There are reports of the air blowing down much further than that during the collapse.
        Bolo Boffin
        Jan 2012
        #10
      
        
        When the volume of a single floor went from 400K cubic feet to zero in fractions of seconds
        hack89
        Jan 2012
        #15
      
        
        "the installation of the charges took place at night and/or on the weekends when people weren't work
        zappaman
        Jan 2012
        #22
      
        
        maybe you and gyroscope can settle this and then get back to the rest of us
        OnTheOtherHand
        Jan 2012
        #29
      
        
        If the core of the tower collapses straight down while the perimeter remains stationary
        hack89
        Jan 2012
        #35
      
        
        The professional building community has been discussing these issues for some time.
        AZCat
        Jan 2012
        #39
      
        
        Hack says that "Buildings are not designed with vertical static loads in mind."
        jesters
        Jan 2012
        #43