Total Building Collapse from a Single Column Failure

[JSanderO]

Discussions in this thread are crossing several areas - legal, structural engineering past practice, possible better standards for future engineering and allocation of accountability to name just four.

Lets look at the legal issues first.

These discussions have arisen because Sander has some concerns about possible design weaknesses in the WTC Towers which may have contributed to the scale of the disaster. I accept that Sander has grounds for concern but the challenge is to getting those concerns in focus and determining what remedial action, if any, the US community should take.

So starting with the legal issues Mark F has pointed to a key factor:
I don't think any of us are forgetting Mark but the reminder is appropriate. Certainly Sander has focussed on the accountability of designers. Let's just explore some legal realities.

Legal remedies fall into two classes:

1) criminal law where the guilty party has contravened a requirement of the community expressed as a statute law. Murder is one crime and that is why I took strong objection to Sander using it as a (false) analogy to the WTC design situation. Murder requires INTENT and it is ridiculous to suggest that those who designed the WTC Towers intended to kill occupants either by the building trapping them in a fire or by collapsing. So forget crime and criminal remedies.

2) civil law where one party is alleged to have "injured" another party. Where "injured" has a broad meaning - actual bodily injury, loss of property or loss of money. even loss of opportunity. Successful civil actions usually result in the award of "damages" - a monetary sum to compensate for the "injury" caused" - whether or not the original injury was bodily injury.

So that is the "Legal Basics 101" setting.

Now "Torts 102" is the area relevant to where Mark's quoted statement intersects with Sanders concerns.

IF << note the "big "IF" - IF there was any action against the original designers it is conceivable that it would be for negligence. Sander has several times referred to "product defect liability" and it is a broadly analogous situation. (And it happens to be one where the evolution of US law has led the "common law" world over recent decades.)

At most, in a cilil action, the negligence alleged by the designers would only have the status of "contributory negligence". I wont pursue the details further because1) it gets too complicated; AND 2) I've forgotten most of it

BUT remember the very big "IF" at the start of this section.

Given the scale of the maliciously caused disaster I do not see any Western style government allowing such an action. Even if existing statute law, case law and precedents permitted it I would anticipate immediate blocking action by Government. The reasons go to the foundation premises of risk and insurance policy and law. They are too far off track for here.

So bottom line - whatever value Sander sees in 'accountability' with or without sanctions - there is no chance of criminal reparations and the possibilities for civil action are very limited - probably non existent.

The remedied for what may have been weak in WTC design lie in the evolution of design. Not individual or corporate sanctions applies retrospectively. I'll leave that for a technical post.

Let's do more IF's...

Suppose a class action suit was filed by the victims' families for wrongful death. (I am not a lawyer). The suit would name all the parties they plaintiffs believed had contributed to the death of the loved ones. These plaintiffs might include. AA, AA security, PANYNJ and the designers/engineers/contractors/DOB and so forth.

The defendants would file motions to have them removed from the case for X, Y, Z reasons. The judge would decide and if the were not dismissed... the case would proceed to discovery and trial unless the defendants offered to settle.

No?

 

[Newtons Bit]

Redundant? How so?

You may have noticed multiple columns being ripped from the building by the plane impact. Losing a single column without a collapse is redundancy in structural engineering.

 

[JSanderO]

You may have noticed multiple columns being ripped from the building by the plane impact. Losing a single column without a collapse is redundancy in structural engineering.

You're not serious?

All structural elements are working at about half their design strength. So yes there is redundancy in every beam, column, bolt and so forth. No one designs a product using material at their yield stress.

Lots of structures suffer serious damage or loss of a column... as well they should.

However, the Twin towers did not have an excessive FOS in the steel and in the core had only 24 columns carrying half an acre of floor area... which is about 1,600 SF per column.

A typical 25' x 25' bay system each column supports 625 SF of floor. Looks to me from this quickie calculation that the Twin towers went with about 40% of the columns of a typical grid frame. And to me that's kinda like putting all your eggs in one basket so to speak.

So sure the could take the loss of a few columns as expected... but each subsequent column failure was a march larger blow to the chance of staying up.... Kinda.

The facade was a structural membrane and less like a collection of columns. Although the membrane was made of box sections and spandrel plates bolted together in a vertical stagger pattern. There were no diagonal braces as the panels acted like vierendiel trusses. So this WAS an effective strategy for dealing with a plane impact.

Not so with the core.

 

[Justin39640]

The lot I refer to was from the land fill from the bathtub. The WFC and Battery Park City were built on it. The lots to the north of WFC diagonally across the intersection of Vesey Street was vacant and was vacant on 9/11/2001. it was used for a parking lot.

Why the developers chose to build a complicated structure over Con Ed is something that needs to be explained. It certainly made from a very complex frame w/ huge transfer trusses and all manner of odd ball framing. WHY? It seems as a no brainer to the developer to purchase the vacant lot and build a simple frame. WHY didn't he?

What was the "lot" being used for in 1982?

Explanation: "Hey guys, look. I see 40+ floors of revenue in Downtown Manhattan in a complex we already own."

There was nothing wrong with 7WTC until a building fell on it. No one should be held responsible for engineering a building that collapsed because of that.

You'd be really surprised what you'll find inside and under buildings in NYC.

Collapse immediately? How would that be? You don't think the building could be knocked over by a plane do you?

Don't be ridiculous. The planes didn't do enough damage by themselves to overcome the redundancy. If they had, you would have seen a similar collapse progression. Just a lot sooner.

The towers collapse because of what happened AFTER the planes hit. Do you understand that?

OF course I do. Hence the building had tons of redundancy to survive the impacts.

If you want to raise a stink, look into the egress issue. Then again, how can you hold anyone responsible for not foreseeing this type of event 20 to 40 years prior?

 

[JSanderO]

What was the "lot" being used for in 1982?

used as a parking lot in 1982

 

[Justin39640]

used as a parking lot in 1982

I'd like to reiterate: There was nothing wrong with 7WTC until a building fell on it.

ETA: There was nothing wrong with the bigger building until radical Muslims crashed a giant airliner into it at full speed.

 

[ozeco41]

Let's do more IF's...

Let's not.

There is no basis for criminal action and it is good to see that you have walked away from those obnoxious suggestions.

Likewise the possibility of civil action at this late stage is remote.

This thread has your OP and post #2, the first response, summarised the status well:

Isn't this a rewritten question of NIST said that this was the straw that broke the camels back and how universal it would be that a single straw actually could break a camel's back?

...a doubly appropriate summary given that the OP had at least two strawman premises to some unsupported claims.

Why not discuss the OP? OR the directly related technical issues which several members have identified.

 

[ozeco41]

I'd like to reiterate: There was nothing wrong with 7WTC until a building fell on it.

ETA: There was nothing wrong with the bigger building until radical Muslims crashed a giant airliner into it at full speed.

Exactly.

And even now NO ONE is likely to design buildings to fully withstand suicide attack by hijacked aircraft.

 

[ozeco41]

...If you want to raise a stink, look into the egress issue.

...and (I would) add in firefighting systems redundancy.

Those were the two causes of the post impact deaths.

 

[jaydeehess]

[qimg]http://conleys.com.au/smilies/clap.gif[/qimg][qimg]http://conleys.com.au/smilies/clap.gif[/qimg]
...and (I would) add in firefighting systems redundancy.

Those were the two causes of the post impact deaths.

Indeed one aspect of the tower fires was the severing of water supply to sprinkler systems. IIRC there was a large tank at roof level but as soon as the pipes were severed it drained all but uselessly at the break(s).

Not sure how one would make such a system redundant. Possibly a pressure sensor that automatically shuts a valve above the break. If the supply is for 20 storeys and the line is broken 10 storeys below the tank, the water gets supplied only to those floors above the break. Not ideal but still works to slow/prevent vertical spread of the fire.

logicically a loss of pressure sense would shut valves at every floor, then begin opening them one after the other beginning at the uppermost floor. As soon as opening one results in pressure loss again, that one recloses and sprinkler systems on floors above that closed valve are primed and operational. Would take about 2-5 minutes I would estimate. Again not ideal but fairly inexpensive and would keep the system partially operational as opposed to useless. A more ideal system would have a tank on every floor supplying water to the sprinkler system of the next lower floor. That would be as close to perfect as I could see possible but rather prohibative in expense and loss of rentable space.

 

[jaydeehess]

I'd like to reiterate: There was nothing wrong with 7WTC until a building fell on it.

ETA: There was nothing wrong with the bigger building until radical Muslims crashed a giant airliner into it at full speed.

Even after another building fell on it, WTC 7 was standing, and would continue to stand, if not for the 8 hours of large area office fires that were not fought, and could not be fought, due to massive infrastructure damage in lower Manhattan plus the large loss of FDNY personel and equipment. I mean really, are we to expect buildings designed to survive no fire fighting effort whatsoever?

** hilited "expect" since yes, some buildings have indeed withstood massive fires that could not be suppressed. (of course they were also in original condition when the fire began). These structures were not designed to specifically fully withstand such abuse though.

 

[ozeco41]

"expect" and "intend" are two measures which we see getting lost sight of in these discussions as we merrily pursue truther defined red herrings - single issue out of context claims or false premises PLUS truther imposed reversed burden of proof. Leading to a lot of futile "discussion".

So we see simple facts being "forgotten" - like steel buildings are vulnerable to fire and all design of steel buildings is premised on "get the people out" by gaining time to start fire fighting. "Save the building" at best a second priority.

Both "expect" and "intend" - when used as design criteria - set minimum targets. There is nothing remarkable about targets being exceeded. And probability says that some targets may not always be reached - arguments based on exceptions are therefore also sus.


OR simple facts like there is almost certainly no such thing as "single column failure" almost certainly no such thing as "single column failure causing..." Neither of those happened to WTC7 and neither of those is either always true NOR never true - it will always be situation specific.

And those two sentences re-answer the OP yet again.

 

[batvette]

There's a lot of technical stuff way over my head here, but the OP's question is moot simply by the testimony of the firefighters on the scene- from debunking911's compilation on the "pull" statement by Silverstein:

So we go there and on the north and east side of 7 it didn’t look like there was any damage at all, but then you looked on the south side of 7 there had to be a hole 20 stories tall in the building, with fire on several floors. Debris was falling down on the building and it didn’t look good.

... Then we received an order from Fellini, we’re going to make a move on 7. That was the first time really my stomach tightened up because the building didn’t look good. I was figuring probably the standpipe systems were shot. There was no hydrant pressure. I wasn’t really keen on the idea. Then this other officer I’m standing next to said, that building doesn’t look straight. So I’m standing there. I’m looking at the building. It didn’t look right, but, well, we’ll go in, we’ll see.

...We headed toward 7. And just around we were about a hundred yards away and Butch Brandies came running up. He said forget it, nobody’s going into 7, there’s creaking, there are noises coming out of there, so we just stopped.

(from the site author:)This proves there was a big hole on the south side of the building. From the photographic evidence and these quotes which aren't meant to be technical, I suspect there was a large hole in the center of the building which may have gone up 10 stories connected to a large rip on the left side of the building which continued up another 10 or more stories. Together they would make "a hole 20 stories tall".

but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse. You actually could see there was a visible bulge, it ran up about three floors. It came down about 5 o’clock in the afternoon, but by about 2 o’clock in the afternoon we realized this thing was going to collapse.

Firefighters using transits to determine whether there was any movement in the structure were surprised to discover that is was moving.

http://www.debunking911.com/pull.htm

So again the simplistic nature of the OP question is absurd. I'm sure if any truthers were here the only thing they'd get out of my post is that "THE NIST IS THEREFORE WRONG AND THEIR ONE COLUMN THEORY IS A LIE" but that's typical, reduce your knowledge to zero and build on it from there.
(and I'm sure most of you have seen these quotes) Just reminding us all what a sick building this was observed to be 3 hours before that column failed.

 

[Newtons Bit]

You're not serious?

All structural elements are working at about half their design strength. So yes there is redundancy in every beam, column, bolt and so forth. No one designs a product using material at their yield stress.

Lots of structures suffer serious damage or loss of a column... as well they should.

However, the Twin towers did not have an excessive FOS in the steel and in the core had only 24 columns carrying half an acre of floor area... which is about 1,600 SF per column.

A typical 25' x 25' bay system each column supports 625 SF of floor. Looks to me from this quickie calculation that the Twin towers went with about 40% of the columns of a typical grid frame. And to me that's kinda like putting all your eggs in one basket so to speak.

So sure the could take the loss of a few columns as expected... but each subsequent column failure was a march larger blow to the chance of staying up.... Kinda.

The facade was a structural membrane and less like a collection of columns. Although the membrane was made of box sections and spandrel plates bolted together in a vertical stagger pattern. There were no diagonal braces as the panels acted like vierendiel trusses. So this WAS an effective strategy for dealing with a plane impact.

Not so with the core.

One of the things that amuses me about the gibberish above, other than it being one giant straw man, is that JSanderO thinks there's a "typical 25'x25' bay system" in steel buildings. There's not. Bay sizes are dictated by architectural requirements and can vary from "very short" to 60ft with typical construction.

25'x25' is also less economical (from a steel weight perspective) than longer bays thanks to A992 steel.

 

[Animal]

One of the things that amuses me about the gibberish above, other than it being one giant straw man, is that JSanderO thinks there's a "typical 25'x25' bay system" in steel buildings. There's not. Bay sizes are dictated by architectural requirements and can vary from "very short" to 60ft with typical construction.

25'x25' is also less economical (from a steel weight perspective) than longer bays thanks to A992 steel.

Yes....30 and 40 ft bays are much more economical.

Have done 60 ft bays as well, but they tend to have issues with too much deflection under heavy snow load. A 1" deflection can (and did) cause issues with interior finished

 

[JSanderO]

One of the things that amuses me about the gibberish above, other than it being one giant straw man, is that JSanderO thinks there's a "typical 25'x25' bay system" in steel buildings. There's not. Bay sizes are dictated by architectural requirements and can vary from "very short" to 60ft with typical construction.

25'x25' is also less economical (from a steel weight perspective) than longer bays thanks to A992 steel.

The twin tower long span erector set assembly using inexpensive truss joists was sure economical... and absent moment connections came apart like a cheap car table ( the same way it went together).

Of course the engineer accommodates the architectural requirements.

 

[LSSBB]

The twin tower long span erector set assembly using inexpensive truss joists was sure economical... and absent moment connections came apart like a cheap car table ( the same way it went together).

Of course the engineer accommodates the architectural requirements.

It's often a good idea to Just Say No to Frank Lloyd Wright...

 

[Newtons Bit]

The twin tower long span erector set assembly using inexpensive truss joists was sure economical... and absent moment connections came apart like a cheap car table ( the same way it went together).

You keep saying this, but provide absolutely no evidence to prove it.

 

[Justin39640]

The twin tower long span erector set assembly using inexpensive truss joists was sure economical... and absent moment connections came apart like a cheap car table ( the same way it went together).

Of course the engineer accommodates the architectural requirements.

They would have stood another hundred years if brainwashed ******** didn't crash airliners into them. The design worked and helped save many thousands of lives.

If everyone got out of the towers and only empty buildings collapsed, would you still be pissed?

 

[JSanderO]

They would have stood another hundred years if brainwashed ******** didn't crash airliners into them. The design worked and helped save many thousands of lives.

If everyone got out of the towers and only empty buildings collapsed, would you still be pissed?

You don't know that. There were reports of a fair amount of rust on the frame.