Posted by Ples E. Schnitz on September 22, 2001 at 16:28:26:In Reply to: WTC Collapse posted by Malachy Larkin B.Arch. Architect. on September 21, 2001 at 04:49:45:
I don't believe the defensive attitude shown herein, at least from my standpoint, is due to any dislike of columns. It stems from second guessing the works of engineers and architects under hediously anomolous events. Loads are loads and vertical resistance to loads are vertical resistances regardless of where they may be placed within a structure. Internal colums to beam connections would have also been under shear and just as subject to rapid oxidation failure as those along the perimeter. The important thing to remember here is that when engineered, the problems to overcome were tremendous wind loads and since NYC is on the Atlantic, a run away hurricane is not out of the question. The structure was basically an exoskeletal(you've heard mention of the "tube" frame design) system which has been proven to be the safest structure where the main threat is high wind or tsunami. This system moves and concentrates the resisting members to the exterior of the frame to resist extreme lateral loads.
This design prevails along the Pacific Rim and theatre. I don't believe it was any "short-cut" to construction time or desire to increase leasable space for according to BOCA colum areas are calculated into rentable areas. In fact, the restriction on glazing is a shortcoming in amenities forced by this design that far out weighs the spatial disruption of a few interior columns. Now, if this building had spontaneously collapsed under normal conditions, then I would be leading the pack to change our ways! The fact that the buildings have performed so well, even foiling an earlier attempt by bomb, leaves no room in my mind for re-evaluating our entire approach to high-density architecture. You would argue that the engineers should have anticipated an airplane crash. They did, and the building did take such an inertial moment quite nicely. I would respond to you that a small asteroid impact, by all logic, is inevidable,but statistically improbable. We have to use some common sense in developing our structures within the knowledge of empirical data, otherwise we would begin to bleed from the ears thinking of all possible effects from all possible events that could damage a building. When you calculate wind loads or snow loads for your designs do you then say yes, but what if the moon were to crash upon the roof of my building whilst it was fully loaded with snow during an 80 MPH wind during an earthquake? I'm not trying to be facetious-but think about it.Ples the "Grumpy"
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