Steel failing in hydrocarbon fires.

[ElMondoHummus]

ElMondoHummus, had they stood, no way would they have been repairable. Too much damage. They would have had to have been shored up and then disassembled.

Actually, you might be right about that. So my "still standing today" line seems to have been a bit hyperbolic. I guess I can cop out by saying their shells might still be standing, uninhabited , but that's a cheap way out. Let me instead amend that by saying they might have stood far longer than they did, and if firefighting efforts would have resumed (much plumbing would've had to have been fixed, I believe), it might have reached the point to where the burnt out structures would have to have been intentionally demolished, and not collapsed on their own. That's actually a better way of putting it.

Then again, who knows? I recall that Arup says that the thermal expansion would've doomed the towers anyway, regardless of SFRM dislogement, so they may have collapsed right when they did anyway. Blech... the ultimate point here is that, regardless of what might have happened otherwise, the NIST study does claim that the failure had multiple causes, and that fireproofing dislodgement and column severing due to impacts, and severely hampered firefighting effects all added up to the collapse. It was more than just the fires burning; it was a combination of all of the damage.

 

[Grizzly Bear]

I know it's shocking to you, but fires, hydro-carbon fires, simply do not harm steel, structural steel high rise buildings.

You see, steel and concrete and specifically designed, engineered, tested and validated, so that in the event of a fire, in the event of a jet crashing, then the building, then the concrete and steel, simply can easily handle the heat and the energy.

You'll have to forgive me if I'm a bit skeptical of this claim when the pertinent sources dealing with this subject contradict your own interpretations.

I'm going to focus on this once more by exposing you to relevant reference material, because... you clearly desire professional resources; here are a few direct excerpts from my own reference material. Your homework will be to obtain the source books and read them:

Source: Fundamentals of Building Construction: Materials and Methods -- Fourth Edition by Edward Allen & Joseph Iano

The above are excerpts from chapter 11.

and

Source: Understanding Structures by Fuller Moore

Chapter 17, page 238

The above material is learned in design based University level courses. As you can see I've referenced this material to a few posters in this section before.

 

[T.A.M.]

now you've gone and done it.

and the reference to people seeing "molten steel" in the debris, in 3....2....1...

TAM

 

[BenBurch]

Actually, you might be right about that. ...

I think it actually would have served the propaganda purpose of the terrorists BETTER had they not collapsed. The constant reminder everybody would have had looking at NYC, like two jagged decaying teeth - much better than for them than the recollection of what HAD been there. And the deconstruction job would have been dangerous and long because there is just no way you COULD have done an implosion on those buildings and not created massive damage and dislocation in lower Manhattan.

They would likely have been taken down to street level, and the underground structures retained. WTC 7 would have been standing and all the other buildings that were destroyed would have been standing still, and there would have been a Memorial Plaza created for the hundreds who died in the wrecks and fires.

And I can't imagine the work could have been done with any safety in less than 5 years.

 

[ElMondoHummus]

I think it actually would have served the propaganda purpose of the terrorists BETTER had they not collapsed. The constant reminder everybody would have had looking at NYC, like two jagged decaying teeth - much better than for them than the recollection of what HAD been there. And the deconstruction job would have been dangerous and long because there is just no way you COULD have done an implosion on those buildings and not created massive damage and dislocation in lower Manhattan.

They would likely have been taken down to street level, and the underground structures retained. WTC 7 would have been standing and all the other buildings that were destroyed would have been standing still, and there would have been a Memorial Plaza created for the hundreds who died in the wrecks and fires.

And I can't imagine the work could have been done with any safety in less than 5 years.

I think you're right about all of that. Instead, the towers have turned into a narrative of heroic rescue efforts, plus American industriousness in working to rebuild the towers. And afterwards, turns cynical with all the issues of design (remember the sturm-un-drang over the design selections?), and cost, but that just serves to buttress my point: The narrative has moved on to what the US does about the site, not what the terrorists did to it to begin with.

 

[Sunstealer]

It's easy to see on Page 111 and 112 of http://www.fire.nist.gov/bfrlpubs/fire05/PDF/f05130.pdf the affect of heat on steel properties. Why do these people think that house and office fires can't reach 600°C by which point structural steels lose approximately half their yeild point and tensile strengths? The data is right there infront of them!

 

[jaydeehess]

I know it's shocking to you, but fires, hydro-carbon fires, simply do not harm steel, structural steel high rise buildings.

You see, steel and concrete and specifically designed, engineered, tested and validated, so that in the event of a fire, in the event of a jet crashing, then the building, then the concrete and steel, simply can easily handle the heat and the energy.

I mean, I'm sure than you can realize that you could not dare design and build a high rise tower, the highest in history at the time, 1972/1973 and bnot expect that there was a chance of a jet striking the tower, right?

The possibilities, even the likelihood was definite, not just possible or potential it was likely to happen

So you design and test and build to accompany that sort of tragedy.

Wow, I did not actually think we would get a truther who so epitomizes the gist of the OP. You fit the bill perfectly and in doing so illustrate the complete technological ignorance of your ilk.

Congradulations and thanks.

 

[ktesibios]

I think it actually would have served the propaganda purpose of the terrorists BETTER had they not collapsed. The constant reminder everybody would have had looking at NYC, like two jagged decaying teeth - much better than for them than the recollection of what HAD been there. And the deconstruction job would have been dangerous and long because there is just no way you COULD have done an implosion on those buildings and not created massive damage and dislocation in lower Manhattan.

They would likely have been taken down to street level, and the underground structures retained. WTC 7 would have been standing and all the other buildings that were destroyed would have been standing still, and there would have been a Memorial Plaza created for the hundreds who died in the wrecks and fires.

And I can't imagine the work could have been done with any safety in less than 5 years.

In the case of the Meridian Bank building fire in Philadelphia, it was seven years before demolition work began.

That time was spent by the city, the owners and the insurers bickering about what was to be done- try to repair and reopen it, deconstruct it to below the fire floors and make a shorter building out of it, or take it down completely- and who would pay for doing whatever was decided.

This was probably a good thing for the three parties' lawyers, but it didn't do the city or its business community any good.

The building had to be reinforced to allow it to be taken down safely; my impression (I worked in Center City Philly at the time) is that the deconstruction, once begun, took only a matter of months.

 

[Dave Rogers]

I mean, I'm sure than you can realize that you could not dare design and build a high rise tower, the highest in history at the time, 1972/1973 and bnot expect that there was a chance of a jet striking the tower, right?

My bolding.

The North Tower (1) was completed in December 1970 and the South Tower (2) was finished in July 1971

Just checking here, professor - you do understand, don't you, that the Twin Towers were designed before being built?

Dave

 

[Architect]

I've never designed a building to resist an aircraft impact in my life.

 

[Toke]

I wonder how thick a rebar concrete wall should be to stop a 120 ton plane at diving speed. And how much office space would be left.

Guess resist does not mean bounce off, but just avoid collapse or critical damage.

 

[twinstead]

Wow. A truther using an argument from incredulity. Who'd of thunk it?

 

[BenBurch]

I wonder how thick a rebar concrete wall should be to stop a 120 ton plane at diving speed. And how much office space would be left.

Guess resist does not mean bounce off, but just avoid collapse or critical damage.

About 1.5 meters.

 

[Holler Hoojer]

I've never designed a building to resist an aircraft impact in my life.

And, of course, there's the corollary: we should, under that criterion, design aircraft to withstand building impacts. Eh?

 

[tsig]

I wonder how thick a rebar concrete wall should be to stop a 120 ton plane at diving speed. And how much office space would be left.

Guess resist does not mean bounce off, but just avoid collapse or critical damage.

You want 3" rebar on 4' centers coated in C4 in case you need to demo the building later.

 

[tsig]

I've never designed a building to resist an aircraft impact in my life.

The towers were not designed to withstand airplane impact. It was more a PR claim made after the towers were built than an engineering reality.

 

[twinstead]

I thought the buildings survived the actual plane impacts fairly well.

 

[Toke]

I thought the buildings survived the actual plane impacts fairly well.

Yes and if not or the heatdamage they might well have survived and been repairable.

I am still curius about what kind of building a plane will just bounce off.
1,5m sounds like you pulled it from a smelly place.

 

[Toke]

Found something!
A nuclear reactor containment building with total thicknes of 2,6m is supposed to stop an airliner. Not as much as I imagined.
Not sure how well that relates to highrise buildings, wind/swaying?
Strenght/weigth rates give some practical limits to how high you can go with what materials.
Thick walls mean less square meters to rent out.
Reenforced concrete is not free, and a plane proof building would cost a fortune.

So professor smartpants building is probably possible to build, i just can´t imagine anyone doing it.

Reactor containment

 

[Holler Hoojer]

I wonder how thick a rebar concrete wall should be to stop a 120 ton plane at diving speed. And how much office space would be left.

Guess resist does not mean bounce off, but just avoid collapse or critical damage.

Google Maginot Line.