I have a theoretical question regarding the collapse of the World Trade Center and didn’t find anything using a search of this board.
First, for the purpose of this question, disregard the element of loss of human life (I said it was theoretical).
From the standpoint of repair and/or demolition, was it favorable that the towers collapsed? If they had not collapsed, could they have been repaired or would they have had to have been demolished anyway? Would repair have been too costly considering the height at which the damage occured and the fact that the building probably would have been uninhabitable for some time due to the damage to the systems. If demolition would have been necessary anyway it seems the costs would have been much higher although more environmentally friendly.
Right now we have the Deutch Bank building that is sitting there vacant and they haven’t figured out what to do with it. It’s not clear whether it makes sense to try to repair it or demolish it.
Anybody have any thoughts, knowledge, links or insight?
Theoretically, if there had been no fire and there had been no collapse, the situation would probably have been a lot worse because of the POTENTIAL for collapse from the structural damage - the area for blocks around would have to be evacuated until the upper floors of the building could be demolished, possibly for a year which would have a huge economic impact. Make no mistake, and speaking as an Architect, the upper floors would almost certainly have had to be demolished. The technique? Look up the old David MaCauley book “Unbuilding” to see how a high rise would be brought down, a piece at a time.
It’s funny you bring this up. About two weeks before the towers collapsed, I looked at them one day (I work only about a block away) and wondered how they would have eventually come down when they got too old to be serviceable. They couldn’t get a crane high enough to start taking down the top. I don’t think a controlled implosion could have done it either.
Any ideas, gsteinma? (And BTW, welcome to the boards!)
Essentially you “unbuild” the building in reverse - a hammer head crane (the kind usually used to erect tall buildings) would be helicoptered in in pieces to the top of the building, where it would be assembled and attached to the building structure. They would use the crane to lower materials, which would be either unbolted or cut away, down to the street. when you build a building, this kind of crane is inched upward with the building structure as it grows. To unbuild, the crane would be inched downward as the structure is removed. The tallest free-standing building ever imploded (on purpose) was the 32-story Mendes Caldeira building in downtown Sao Paulo Brazil in 1975 (See the Controlled Demolition Inc. website).
IIRC, the PBS show about the tower collapses said that if the fire had not overwhelmed the insulation, the buildings would have survived and been reasonably repairable. In short, if they hadn’t collapsed, they would have been fixed.
I saw that same special, the Discovery special, AND read with great interest the recent article (Time or Newsweek, I think) which detailed the last moments of the people trapped on the upper floors (based on cell phone conversations). The building floors were supported by the exterior “skin” stucture and the interior “core” with no other columns. The airplanes in each building took out almost one whole side of the exterior skin, and almost certainly cut through or severly damaged most of the columns in the core (remember the second plane burst through the other side) if not all of them. In the article it mentioned that there were people trapped on the floors above the damage because they could not open the doors to their offices and conference rooms - they were jammed in their frames because the frames were twisting. This indicates that there was at least some structural collapse of the floors beginning immediately after the crashes. I don’t think they would have torn the buildings down completely had they survived, but I think that certainly the upper floors would have had to have been demolished, and rebuilding them would have been a big "economically feasible"question
I doubt the center columns were damaged severly. The reason you saw the plane exit the other side (besides the fact that a bunch of scumbags flew a plane into it) was because the force went around the structural part.
This is what happened during the 1st attack on the WTC about 9 yrs ago. The force of the bomb blew out non structural components basically right around the structual ones.
True but the structural members in the basement where the bomb went off were the thickest, heaviest members in the building because they supported over 100 floors. The members get thinner and lighter as they go up. A 767 has a takeoff weight of 450,000 lbs and you all saw that the second plane dissapeared entirely inside the building when it hit it at over 500 miles per hour - it cut through the building skin (which consisted of steel plate column assemblies only a couple of feet apart - heavier than the interior core columns) like it was made of cardboard. IMHO it would be impossible for the core columns to have escaped unscathed because there was nothing between them and the outside but drywall and furniture, and with 450,000 lbs hurtling at them at subsonic speeds surely they must have at least been bent a little, which would have compromised their structural integrity anyhow.
I read that the core and one stairwell were partially protected because the first plane happened to hit the floor that contained huge (and heavy) equipment that lifted the elevators.
I don’t see how that could have happened. Plane #2 hit at 586 MPH according to radar. There is no way the non-supportive sheetrock walls stopped it from rupturing the core. Certainly the steel skin started shredding the plane immediatly, but I would think it couldn’t have done much past the cockpit and first class, which must have been instantly destroyed by taking most of the force, leaving the rest of the plane to head straight for the core. With the ensuing massive explosion the core must have been torn apart at the impact floors. Because most of the explosion force went straight out the other side probably two of the outer walls were left to support the rest of the floors. I imagine if the planes had hit about halfway down (or up) the building they would have collapsed almost immediatly or within minutes. When close-ups of the south tower were shown on TV it appeared to me to be slightly leaning above the impact floors, which could idicate loss of core support.
I don’t think gsteinma’s idea would have worked. No one would want to put a crane or people on top of severely damaged buildings. Heavy helicopters would seem to be the best solution, until deconstruction could get well past the impact floors to safely rebuild the buildings or the “unbuilding” suggested by gsteinma.
The cleanup may have ended up being cheaper than repairing or unbuilding damaged buildings. But repair of damaged buildings is far more preferable. Far less loss of life in that case.