Posted on 10/05/2001 10:08:02 PM PDT by JohnHuang2
Edited on 04/29/2004 1:59:07 AM PDT by Jim Robinson. [history]
While the article does have a certain "well duh" quotient, there are some significant questions which this type of analysis could answer. Among these, which structural members failed when, how hot they got before they failed, etc. Unfortunately, most of the evidence got rather badly crushed and it's hard to tell what damage occurred before the building started its progressive collapse and what damage occurred after.
One thing I suspect may have hastened the collapse would be the transfer of heat between structural members which were broken by the plane and those which were--including fireproofing--intact. If a large assembly of steel beams and girders is encased in fireproofing except for an exposed portion which is sitting in a raging fire, the fire may be able to heat all of the connected beams--even those not exposed to it--to over 900 degrees causing them to lose half their strength. If that indeed occurred, it would suggest a need for thermal insulation between stuctural support members, rather than just enclosing the support structure as a whole.
Equipment, no. People, yes. If Halon extinguishers go off you've got seconds to get out before being smothered.
I have heard that the full load of fuel was what actually melted the steel and caused the building to collapse. I also heard the heat from the fuel was 2000 degrees, not 1000.
My guess about the reason of the stuctural failure would be that thousands of gallons of burning jet fuel flowed down the elevator shafts into the basement and weakened the supports at that level. Take out the load bearing supports in the basement and you have an implosion effect, take out the supports on the 42nd floor and more likely your columns would fail earlier at the point of impact that other points and the tower would fall to one side like a tree cut down.
I am no engineer but I think this sad event will change the design of skyscrapers in the future.
Haylon works great for an enclosed fire with relatively low heat levels but would not work effectively on jet fuel. The other problem with haylon is that it is no longer manufactured. It's not ozone friendly.
A foam system would have helped, but it would have required massive amounts of foam to have controlled such a large fire that happened in an instant. In addition, any fire suppression system in place in the building would have been partially destroyed by the initial impact.
The design of the building gave thousands of people the time to get out. I doubt that any fire suppression system could have done more than slow the process down by more than a few minutes.
I agree - and what kind of fuel tank capacity did a 707 of that vintage have?? Certainly the 767 has a much larger capacity?
Actually, halon makes it easier to get out by not decreasing visibility like CO2 and dry chemical or making the floors wet and slippery like sprinklers. You would not be smothered by the halon, but you would quickly be overcome by the toxic gasses of incomplete combustion. Halon itself is relatively harmless to humans and does not displace the oxygen in the room.
There are several "clean agent" supression systems available. None are quite as effective as halon and they are not "drop in" replacements. You need to replace the whole system, not just the halon tanks. The halon can then be sold to a recovery company that can resell it to owners of existing halon systems.
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