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Politics : Moderate Forum -- Ignore unavailable to you. Want to Upgrade?

To: TigerPaw who wrote (16239)	3/30/2005 4:56:21 PM
From: Raymond Duray	Read Replies (1) \| Respond to of 20773

TP, Re: As I understand the innovation of the Twin Tower design is that the center of the building was not load bearing That is not correct. In structural engineering, unlike electrical engineering, there is a concept called "tributary load". Thus we examine the large open floor plan of the WTC Towers and we find the centerpoint of the span of the floor trusses. Half of the load of the floors is carried by the exterior columns and the other half is carried by the central core columns. Additionally, as you can see from the photos, the central columns carry themselves and the service core, including the stairways, elevators, mechanical risers, etc. So most of the static and live gravity loads are carried by the central core. The central core is the main load bearing element of the building even before you begin to analyze and plan for the dynamic loading imposed by earthquake, plane impact or the wind. As is almost always the case with hirise construction, wind loading is the most severe load to be calculated. In the case of the WTC towers, the wind load design value was 140 MPH. What this meant was that there was a great degree of stiffness introduced into the core columns by means of diagonal bracing, providing a vastly stronger mesh of construction than would be required merely for a gravity load. What I dispute regarding the "official story" (a real fairy tale) is that the extremely strong central core could or would collapse in a circumstance where the building "pancaked". There are some tantalizing pieces of evidence that the core was demolished. For instance, demolition contractor Mark Loiseaux, among others, noted finding melted metal, presumably A36 structural steel in the deep subbasements weeks after the collapse of the buildings. There is, quite simply, no reasonable explanation or any explanation of this at all in the Kean-Zelikow report. One of dozens of curious omissions in that report. Let me know if I can provide you with any more structural analysis from the skeptic's community. The most famous of these items resulted in one clear-eyed engineer being dismissed not for flying off the handle, but rather for getting too close to the truth: septembereleventh.org There are many conspiracy theories floating around about the collapse of the WTC towers and 9/11 in general, but the only conspiracy theory that is totally debunked is the so-called "official story". commondreams.org