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Politics : Bush-The Mastermind behind 9/11? -- Ignore unavailable to you. Want to Upgrade?

To: sea_urchin who wrote (9144)	12/5/2004 8:48:18 PM
From: Raymond Duray	Read Replies (1) \| Respond to of 20039

Re: I was under the impression that the steel in the box-columns was enclosed in concrete. Is that not so? The heavy (4 inch thick) steel columns in the sub-basement parking levels were encased in concrete, to the best of my knowledge. However, above that level the means of fireproofing the structural steel columns was a spray-on asbestos containing foam that was very friable. Most of the columns were additionally segregated from the occupied portions of the building by a two-hour rated assembly consisting of two layers of "Type X" gypsum wallboard mounted on steel stud framing. Here's a good description of the actual structural engineering of the WTC towers. tinyurl.com