On Wed, 12 Sep 2001 20:18:35 -0400, you wrote:
>In another post, I speculated the trajectory was planned to take out a corner of the
>building to maximize the probability of instability. Video on TV showed the plane
>aiming about 2/3 across the entry face. Also, the plane was banking, perhaps to dump
>fuel on as many floors as possible. Even so, relatively few floors were initially
>impacted.
>
>> The WTC planes had full tanks and remained buried in the building.
>>
>> I've been designing commercial buildings for twenty years, and I don't
>> know of a way to design a building to withstand that kind of heat.
>> Especially not one 110 stories tall.
>
>There are certain things you can do:
>
>Not put all your structure on the perimeter. Distribute it over the floor space.
>Tennants don't like this, because it breaks up the floors. Tough.
Actually, the buildings were a "core frame" design, with little or no
structure at the perimeter. This design is more flexible in high
winds, a much more likely threat to a skyscraper.
A plane "taking out" a corner of the building would have done little
damage. In fact, the building would likely have been repairable.
>Require fairly tough, layered insulation on major support structures. I suspect 1
>foot of layered firecode GWB and fiberglass (3 or 4 layers of each) would be
>sufficient. The objective here is to delay, preferably for several hours, the
>reduction in yield stress due to the beams heating. The higher the building, the
>more protection required. It could be tapered with height. Had the building not
>collapsed for 4 hours, the death toll to occupants would have been much reduced.
>Walking down 110 stories, even under the BEST of conditions has to take more than an
>hour. Consider people not in the best of condition, high heels, etc.
Actually, many people did in fact walk down the full height of the
building and to safety.
>How about requiring sprinkler pipes running down the major columns from a water
>tank, perhaps from reservoirs every 20 +/- floors? The water could be released by
>fusible links at high temperatures (300 to 400 degrees) to cool the beams.
There was a full sprinkler system in both buildings, which was
destroyed in the crash. But at 1600 degrees, water is useless. It
would simply turn to steam and dissipate.
>It all comes down to a matter of money. Building owners want to maximize their
>return. It is simply a price/safety tradeoff.
Not really, the safety systems in a building the size of the WTC cost
many times the cost of the structure. It's just that no one expected
someone to intentionally fly a plane into the building. Remember,
those buildings were designed in the 60's.
This archive was generated by hypermail 2b29 : Mon Oct 08 2001 - 10:58:58 PDT