So say 9/11 happened and the planes rammed into the towers but they didn’t collapse like they did on the day. What would have happened? Would they have had to be demolished anyway? Could they have been repaired?
I thought the impacts of the airplanes sheared all the water pipes. If they hadn’t collapsed, how would the NYFD been able to prevent the fires from consuming most of the buildings?
It’s not really a hypothetical question because of the construction method used and the nature of the damage. It was built like a tube inside a tube where the outer tube was held in tension by the floor joists. Take out the joists and the outer walls punch out from the weight above. What doomed the buildings was the insulation on the steel. It was not the manufacturing brand but method of adherence. While the structure of the building was designed to take the impact of an airplane nobody took into account what would happen if the insulation was blown off during impact.
The steel beams in the Empire State Building are insulated in a cement-like compound that apparently stays on better since the building survived the impact of a B-17. It was also built with a lot more steel. If you were to compare the 2 buildings you would see the difference in interior space. The WTC buildings were much more open.
The short end of this question is that the buildings were too heavily damaged to survive. Once the steel joists were heated and failed it was a done deal. The buildings were coming down. Ironically, had it been a wood structure it would have probably stayed up longer (but not survived).
Magiver, that’s a very informative post but it doesn’t answer the OP’s question at all, which I think is an intriguing one.
Suppose some facet of the steel support structure had been made differently so that the building would NOT have come down, but would simply have had the top floors burn out. What then would have been done? Would they have had to demolish it anyway?
It would have been a sticky wicket indeed. I have a hard time believing that one could prove the buildings were safe enough to go up 70 floors and start rehabilitating. Getting the equipment up there, not to mention the repair steel, doesn’t look very easy at all.
Bringing them down would probably be the way to go. Of course, providing the demolition crew is willing to go into it. Whether they could protect #7 well enough to save it during a controlled demo is another question, I rather doubt the footprint of destruction would have been that much smaller with a controlled demo.
If the buildings had not collapsed, the fires would have raged a lot longer and would likely rendered the buildings unsalvageable even if the structure remained. (A lot of the people who died in the collapse would have just died in the fire instead, so I don’t think the survivor could would have dramatically increased either.) Controlled demolition would probably have eventually been the only option although I don’t know how that would have been accomplished.
I know what you’re saying but it’s like asking what would have happened if the Hindenburg hadn’t been painted with rocket fuel. The hydrogen would have still burned at the same rate if ignited.
If the question is: “would the WTC be rebuilt if less damage occurred?” Well, that question has already been answered twice. On Feb 26, 1993 a truck bomb blew a hole in the basement that took out multiple floors. It caused a half billion dollars damage. There was also the fire on Feb 13, 1975 which burned 65% of the 11th floor (1,300 deg F fire did not damage trusses so the insulation worked well when intact).
Right, the building dropped in a fairly controlled manner to begin with.
Which leads me to this thought;
If they were brought down as the conspirators would have us believe (detonated), why would they choose to bring them down in a controlled manner? Why not just load up one closet on the tenth floor with a thousand pounds of TNT and let 'er rip?
Minor note, the kinetic energy of the bomber that hit the Empire State Building was far less than the KE of the fully-fueled jet that was flown into the WTC at ~600mph. This definitely had a big effect on the outcome.
I do agree with your conclusion though, those floors were heavily damaged and trying to go up, fight the fires and then rebuild would have been very difficult. The top floors, above the impact zone, would be waiting to fall down and start the catastrophic collapse that took place.
Even so, the Empire State Building was constructed in a much more dense fashion than the WTC towers. In 100 mph winds, the top floor of th ESB won’t deviate more than .75 inches. It is one tough building.
Was the jumbo jet really doing 600mph? I thought it was going much slower so it could be sure to hit the target?
My wag is if they stood, the damaged floors and the floors above that would have to be removed, and if desired rebuilt.
As for the pipes being destroyed, it would seem like the FD would use the pipes up to the floors they could and use hand lines from that point up. I don’t know about the water pressure issue though, would booster pumps be needed, or could the pumpers, and for that matter the fireboats, produce enough pressure that could pump water up that high without bursting the hoses and standpipes.
Big-city skylines are full of this question: When the day comes that we no longer want (say) the Sears Tower, and want to replace it with an even taller building, or the citizens of Chicago went collectively bonkers and decided they’d much rather have a park on that location, how do we safely and effectively remove tall buildings?
You can’t just have Controlled Demolition show up and shoot the building - it’s too tall. The current record for a building intentionally dismantled by explosives is 23 stories. Besides, it’s right in the middle of many other buildings that are to be kept intact. The shock waves from the explosions and collapse will shatter windows for quite a distance.
About the only safe method would be to unbuild the building, working in reverse order of its construction. Strip out the interiors - walls, ceiling tiles, floor coverings, electrical and plumbing, etc. and haul it all out. Jackhammer the poured concrete floors. Then take out the windows and start cutting the structural steel apart, floor by floor, until you’re at ground level.
This would be bad enough in an intact and structurally sound building, but unfathomable in a damaged building. In the case of WTC, on the presumption that the structure was intact enough to let the building remain standing with huge holes in it, are the elevators still operable to haul out the debris? No? You’ll either need to put in a new elevator, or cut holes in the floors to set up a chute system to carry debris to a level that has working elevators. You might also want to have the architechts engineer some bracing to patch up around those holes so the thing doesn’t collapse while you’re working on it.
As for the OP’s question, on the assumption that the buildings didn’t collapse, they’d be repairable to some extent. If it doesn’t fall down, it can be fixed. Decisions would have to be made quickly to either repair the damage and restore to September 10 condition, or dismantle everything above the damage and wind up with shorter buildings.
Frankly, any repair would probably be economically unfeasible, given the number of floors that were directly hit, the fire damage (smoke, soot, etc) above that point, and water pouring down through the rest of the building.
As a point of comparison, the 40 story Deutsche Bank Building at 130 Liberty Street, directly across from the South Tower of the WTC, was severely damaged on September 11, 2001, with a gaping hole in the building face toward the WTC site.
After much debate and environmental analysis and testing, it was decided that the building will beabated and deconstructed.
FWIW by way of comparison, here in Philadelphia One Meridian Plaza was badly damaged by a fire about fifteen years ago (eight of 38 floors gutted, three firefighters killed). As 9-11 conspiracy theorists are fond of pointing out, it didn’t collapse (of course, it wasn’t hit by a plane either, nor did the eight floors ignite simultaneously, nor were they doused with jet fuel; but these details are irrelevant in CT Land).
Eventually, after several years of legal wrangling, Meridian Plaza was demolished by being dismantled from the top down–unbuilt, in the manner described by gotpasswords. IIRC, building engineers had declared it unrepairable; the legal wrangling was over who would pay for the demolition. I can’t remember how long the demolition took, but it seemed like forever.
Yes, if I remember correctly the aircraft exceeded Vne (velocity never to exceed). You don’t have to slow down to steer, you have to slow down an aircraft to land. Otherwise you’d need 12 mile long runways and tires made of asbestos. The whole point of the collision was to impart as much damage as possible. I guess if you’re not worried about pulling the wings off you can get away with it at least once.
The true damage was not the impact but the weakening of the metal from heat. If the insulation had stayed on like it did in the 1975 fire the buildings would still be there.
i was gonna offer up the meridian building as an example. ryobserver beat me to it.
the meridian building (as did the wtt) had asbestos fire protection on the steel. the towers had to stop using asbestos somewhere between the 40th and 50th floors (meridian was shorter and missed the asbestos stoppage). meridian did not have an impact and a fire, just a fire. it also had been grandfathered so that only on floors that had a certain percentage of renovation would sprinklers be required. the fire burned until it reached a sprinkled floor.
the survey pictures after the fire were amazing. in some places the steel deformed over 4 feet, huge, huge, warping of the floors. the demo went very slow due to toxic and very hazardous materials. floors would have to be encased as they were demoed, then disposed of properly. the floors that did not have fire damage, did have water damage; and the mold was rather close to what you see in houses damaged by katrina. that building sat for years just incubating icky things.
if the towers had survived somewhat intact, the cost of dealing with the toxins created by the fire and the hazardous materials would make it cheaper to demo than fix. the demo would have to start from the top and work it way down the building. it would probably take quite a few years.
This book covers that in an entertaining manner.
Don’t expect too much technical advice from it, though.
The Landmark Tower in Fort Worth Texas had 30 floors and was imploded on Saturday, March 18, 2006:
Many buildings around it had to be prepared for the implosion, and came out OK. my EWAG is that preparations for buildings around taller future demolitions are doable, but then it would be too expensive to destroy the building that way.
I believe all really tall structures are designed to be unbuilt. Certainly a damaged WTC could have been unbuilt if necessary.
What would have happened that an engineering study would have been done to determine the damage, the new weak spots, and several options would be weighed. One would be to unbuild the building down to the damaged floors, then either repair and rebuild, or just cap the building off at the new height. If there was no systemic damage to the building’s core and foundation, that’s probably what would have been done.
If it was determined that the entire building was not economically salvageable, then a plan would have been created for dismantling it. That plan might have included temporary reinforcing to make it safe, repair of elevator shafts or other means of hauling equipment up, etc.
The Landmark falls short of the record since the Hudson Department Store was 439 feet.