Why aren't the WTC tower construction drawings publicly available?

[Diazo]

I would expect that by 2000, the plans, at least the ones necessary for ongoing operation, had been put into a CAD system. That system was away from WTC or there should be backups. Making copies is easy, it just takes permission and money.

I would have to disagree with this.

I work as a draftsmen, the ones who actually have to do the conversion to the CAD drawings, and I see no reason that they would have.

There certainly would have be CAD drawings of floor spaces and tenant areas that are used for lease agreements and such, but not of the tower itself.

They have the original drawings that they can reference as needed, why would they spend the money to convert them to CAD when there are no significant changes to them?

Remember that this is a high rise with a LOT of drawings, this is not a 2 day project for a single person. That is a large amount of money for them to spend for no real gain.

And if the as-built copy was on site, which is quite likely, then it would have been destroyed in the collapse. This would leave no copies of the actual as-built drawings, just the original For Construction drawings. And who knows how complete those are after this long?

To get back on topic, the real reason is the copyright issue. I just wanted to comment as this does fall within my realm of experiance.

 

[HeyLeroy]

Do you have any idea what the impulse was or do you just think global collapse had to ensue?

A fair idea, yes. Nicepants showed some simple calculations that demonstrated that the collapsing sections would exert a force 39 times greater than at rest, simply by falling ten feet.

Do you realize what that means? A ten-storey section, falling ten feet, would exert the equivalent force as a 390-storey section in stasis. A 20-storey section, falling ten feet, would exert the equivalent force as a 780-storey section in stasis. A 30-storey section, falling ten feet, would exert the equivalent force of a 1,170-storey section in stasis.

I'll reiterate, the Twin Towers each had a one-acre footprint. Are you going to argue that the lower portions would somehow defy known physics and magically arrest those collapses?

Are you going to continue to argue from incredulity?

 

[chipmunk stew]

I would have to disagree with this.

I work as a draftsmen, the ones who actually have to do the conversion to the CAD drawings, and I see no reason that they would have.

There certainly would have be CAD drawings of floor spaces and tenant areas that are used for lease agreements and such, but not of the tower itself.

They have the original drawings that they can reference as needed, why would they spend the money to convert them to CAD when there are no significant changes to them?

Remember that this is a high rise with a LOT of drawings, this is not a 2 day project for a single person. That is a large amount of money for them to spend for no real gain.

And if the as-built copy was on site, which is quite likely, then it would have been destroyed in the collapse. This would leave no copies of the actual as-built drawings, just the original For Construction drawings. And who knows how complete those are after this long?

To get back on topic, the real reason is the copyright issue. I just wanted to comment as this does fall within my realm of experiance.

As a mechanical designer, I do a lot of drafting, too. My company's devices reach nowhere near the complexity of a skyscraper, and yet a good 25-50% of the drawings for some of our older devices are still hand-drawn, dating from the '70s and earlier.

The goal of every engineering group is to make as few documentation revisions as possible because it uses an enormous amount of resources that they'd rather spend elsewhere, and every change carries risks. It's a wasteful and risky business decision to change the format of a drawing unless it adds some clear value to a project or process.

 

[NYCEMT86]

RealCDDeal,


Call these numbers, if you want to see if you can get a copy of them.

212-566-5000 NYC Dept. of Buildings
212-435-7000 PAPD Corporate Headquarters

or contact Yamasaki & Associates


maybe you and the rest of the twoofers can do some real investigative work instead of looking at pictures and making assumptions.

 

[Tony Szamboti]

A fair idea, yes. Nicepants showed some simple calculations that demonstrated that the collapsing sections would exert a force 39 times greater than at rest, simply by falling ten feet.

Do you realize what that means? A ten-storey section, falling ten feet, would exert the equivalent force as a 390-storey section in stasis. A 20-storey section, falling ten feet, would exert the equivalent force as a 780-storey section in stasis. A 30-storey section, falling ten feet, would exert the equivalent force of a 1,170-storey section in stasis.

I'll reiterate, the Twin Towers each had a one-acre footprint. Are you going to argue that the lower portions would somehow defy known physics and magically arrest those collapses?

Are you going to continue to argue from incredulity?

Alright, I guess I have to show you why that calculation is garbage. There is no chance that the impulsive load was thirty-nine times greater than the weight of the falling section. The equation for impulsive loads is the change in momentum/duration of collision. The velocity in a ten foot drop is 25 feet/second. In order to have a 39g impulse the collision time would have to be 20 milliseconds and that is also in the extreme case where the moving mass loses all momentum. This is extremely unlikely in a situation where fire weakening purportedly caused the initial collapse. The beams would not have instantaneously lost all of their strength. There should have been a slow decent if it was due to fire weakening. Many of the beams would also have been intact slowing the fall. I am not arguing from incredulity. I have looked at this myself in the last year and I am a mechanical engineer. If you simply believe the 39g impulse legend, and I did at one time, then it seems you are arguing from naivety.

 

[Gravy]

There should have been a slow decent if it was due to fire weakening.

There was, until enough columns exceeded their yield strength and buckled, causing a rapid chain reaction and global collapse.

Have you done any momentum calculations?

 

[Tony Szamboti]

A fair idea, yes. Nicepants showed some simple calculations that demonstrated that the collapsing sections would exert a force 39 times greater than at rest, simply by falling ten feet.

Do you realize what that means? A ten-storey section, falling ten feet, would exert the equivalent force as a 390-storey section in stasis. A 20-storey section, falling ten feet, would exert the equivalent force as a 780-storey section in stasis. A 30-storey section, falling ten feet, would exert the equivalent force of a 1,170-storey section in stasis.

I'll reiterate, the Twin Towers each had a one-acre footprint. Are you going to argue that the lower portions would somehow defy known physics and magically arrest those collapses?

Are you going to continue to argue from incredulity?

I looked at the calculations you provided a link to and see where he says that is with a 3 inch stop distance. Nicepants was probably using the equation for velocity shock, G = 2 x drop height/deflection. He would actually be wrong about the 3 inches there as it would be closer to 6 inches in order to get a 39g impulse out of a 10 foot drop. However, just take a look at the North Tower's collapse initiation and see if you believe the initial impulse stopped in 6 inches. It appears that there was tremendous deflection, mostly of the upper block, of somewhere around 40 feet or 480 inches. Given all of that deflection, the fall won't even generate 2g's let alone 39. If you think about it and look at it honestly you will see that, even if a collapse was possible it would have been arrested as the impulsive load could not have been great enough to continue the collapse.

 

[Gravy]

It appears that there was tremendous deflection, mostly of the upper block, of somewhere around 40 feet or 480 inches.

Evidence?

 

[Minadin]

I would have to disagree with this.

I work as a draftsmen, the ones who actually have to do the conversion to the CAD drawings, and I see no reason that they would have.

There certainly would have be CAD drawings of floor spaces and tenant areas that are used for lease agreements and such, but not of the tower itself.

They have the original drawings that they can reference as needed, why would they spend the money to convert them to CAD when there are no significant changes to them?

Remember that this is a high rise with a LOT of drawings, this is not a 2 day project for a single person. That is a large amount of money for them to spend for no real gain.

And if the as-built copy was on site, which is quite likely, then it would have been destroyed in the collapse. This would leave no copies of the actual as-built drawings, just the original For Construction drawings. And who knows how complete those are after this long?

To get back on topic, the real reason is the copyright issue. I just wanted to comment as this does fall within my realm of experiance.

I agree completely. We have drawings in my office from as recent as 12 years ago, which are hand-drawn, and none of them will ever likely be converted to CAD files. In many cases, even our rack sets for recent buildings, which are drawn in CAD, will have minor changes noted on them by hand.

 

[Tony Szamboti]

There was, until enough columns exceeded their yield strength and buckled, causing a rapid chain reaction and global collapse.

Have you done any momentum calculations?

I don't see any slow decent in the initial collapses. There are very sudden.

If nine core columns were completely destroyed in the impact do you know how many columns in the central core would have had to lose at least half of their strength due to fire to allow a collapse?

As I said above, to get that number of G's (39) out of the collapse the upper block would have to lose all of its momentum, and also do it with only a 6 inch deflection. You also need to be totally free of any obstructions to get the 25 feet/second velocity, and that is unlikely as all of the beams would have to move instantaneously. The problem is that none of these things are likely and just don't happen like that in the real world.

 

[Tony Szamboti]

Evidence?

The videos of the collapse initiation. If you want to take a look at some photos of it look at Gordon Ross' paper on Dr. Bazant. He shows the tremendous deflection of the upper block.

http://www.911blogger.com/node/9154

 

[R.Mackey]

However, just take a look at the North Tower's collapse initiation and see if you believe the initial impulse stopped in 6 inches. It appears that there was tremendous deflection, mostly of the upper block, of somewhere around 40 feet or 480 inches. Given all of that deflection, the fall won't even generate 2g's let alone 39. If you think about it and look at it honestly you will see that, even if a collapse was possible it would have been arrested as the impulsive load could not have been great enough to continue the collapse.

40 Feet??

No way. That's 5% strain in the eighty stories below impact. Not going to happen.

Besides, you have another problem. If the lower block deforms 40 Feet trying to arrest collapse, then the upper block isn't falling just one story any more. It's falling five. One before contact, and four during. You now have five times as much energy to squirrel away as you did before.

Like I said, Not Going to Happen.

As others have no doubt suggested, go read Dr. Bazant's latest, and then try again.

ETA: Oh yes, those pictures. What floors are those lines drawn on, realcddeal? Be precise.

 

[Gravy]

I don't see any slow decent in the initial collapses. There are very sudden.

Do you dispute the inward bowing of the exterior columns?

 

[Tony Szamboti]

40 Feet??

No way. That's 5% strain in the eighty stories below impact. Not going to happen.

Besides, you have another problem. If the lower block deforms 40 Feet trying to arrest collapse, then the upper block isn't falling just one story any more. It's falling five. One before contact, and four during. You now have five times as much energy to squirrel away as you did before.

Like I said, Not Going to Happen.

As others have no doubt suggested, go read Dr. Bazant's latest, and then try again.

ETA: Oh yes, those pictures. What floors are those lines drawn on, realcddeal? Be precise.

I had the same questions about which floors the lines were drawn on and wondered if there was contrivance. It doesn't appear there is as the lines are drawn below the aircraft impact in both the before and after collapse photos. To make it look worse the bottom line would have to be moved up and then it would be in the aircraft impact zone. It appears the lines are accurate and there was a tremendous deflection of the upper stories at the initial collapse impact. The upper block isn't falling 40 feet more in free fall as it is deflecting. Also, not that it is important to the argument, but remember that each story in the twin tower buildings were 12 feet so 40 feet would be a little more than three stories.

There is a real problem with the amount of impulsive energy to continue the collapse. You won't get another forty foot fall if you don't have the energy to get there. It doesn't appear the lower block did deflect the same amount in those photos.

 

[Gravy]

The videos of the collapse initiation. If you want to take a look at some photos of it look at Gordon Ross' paper on Dr. Bazant. He shows the tremendous deflection of the upper block.

http://www.911blogger.com/node/9154

I think I'm not understanding your terminology. What do you mean by deflection of the upper block, and which tower are you referring to?

 

[Tony Szamboti]

Do you dispute the inward bowing of the exterior columns?

I have said before that I believe that inward bowing occurred due to the central core collapsing first. The core collapse would have pulled the perimeter columns inward via the floor trusses.

 

[Tony Szamboti]

I think I'm not understanding your terminology. What do you mean by deflection of the upper block, and which tower are you referring to?

I am speaking of the North tower. The deflection is the deformation of the upper block as it contacts the lower block. Look at the link I provided to see the photos. You don't have to read the article to see what I am talking about.

The equations for velocity shock or impulsive loads involve deflection. Deflection is in the denominator, so the greater the deflection the lower the shock or impulsive load. This is why the auto manufacturers design your car to crumple in a collision so as to protect you from high shock loads or decelerations. They are absorbing the energy over time and that lowers the number of G's experienced.

 

[Gravy]

I have said before that I believe that inward bowing occurred due to the central core collapsing first. The core collapse would have pulled the perimeter columns inward via the floor trusses.

And the core collapsing wouldn't lead to global collapse, in your opinion?

 

[Tony Szamboti]

And the core collapsing wouldn't lead to global collapse, in your opinion?

Not a continuing collapse. The problems I mentioned above are why a continuing collapse is improbable. Without enough of an initial impulsive load where would the energy come from for that to occur?

 

[Architect]

Catching up on post-sick leave work, hence the relative silence from this source.

Firstly let me clarify the ownership of designers' drawings; in general, ownership and copyright remain with the originator and the commissioning client is licenced to use it for purposes resonably connected thereto. This would include, in my professional opinion, an investigation into structural failure but might not necessarily extend to publication of (say) the detailed drawings or specifications themselves.

In the UK, drawings submitted for statutory consents (notably planning permission and building warrant) will be held on file for a considerable period. Planning drawings are subject to public consultation and hence accessible to all and sundry, however they also tend to be rather outline (RIBA stage C or D normally) and hence of little relevance here.

There is something of a debate regarding access to Building Warrant here under the terms of the various UK FoI legislation and which has yet to be resolved, a process I am involved with on behalf of my professional institute, and for what it's worth I believe local authorities will eventually be obliged to provide public access saving for where there are security considerations. Nevertheless it is important for those of you outwith the construction industry to understand that even Warrant drawings contain less detail than you would expect (RIBA stage D or E, depending upon project type).

In fact there are two sets of drawings which we would have to examine; what's called "Production Information" in the UK (RIBA stage F/G/H) and the "As Built" (stage K/L) drawings as an earlier poster noted. Even on a small project (say £5m) these will run into hundreds covering everything from general arrangement of steelwork, steelwork fabrication, firework, servicing, linings and partitions, and servicing. Do not underestimate their complexity. Our ISO 9001 QA system has an entire manual devoted to how we manage such information amongst a multi-disciplinary design team, never mind how they are developed.

This is before we even get to the specifcation and other contract documents, or performance specification/contractor-designed items.

It would be surprising in the extreme if an archive set of this information was not available to the architects, etc. today. I am mindful, however, that there may be questions over the extent of material archived (in the UK we generally prune files heavily after 10 or 12 years, depending upon legislative regime and liability periods) and longevity of storage medium (microfiche was, of course, popular in the 60s and 70s but has marked shortcomings). Therefore the question as to what Robertson might have been able to make available is more difficult than might be thought.

Now consider a scenario where the drawings are released. We might have the architect's general arragement (GA) drawings, which are no more than a broad schematic. For steelwork we'll have to trawls through hundreds of structural drawings (and calcs). But fireproofing will be dealt with seperately, either by the architect or more probably a specialist sub-consultant. Then suppose that we want to look at how ventilation ducts might have served as a fire path. Out with the mech-eng drawings. But the fire proofing for this may be somewhere else........etc etc.

In short, forensic analysis of construction drawings is hard. Ask any solicitor who's been involved in a professional liability claim for a complex large-scale problem. Conclusions can only be drawn after rigorous expert scrutiny.

As for CAD conversion of drawings, the simple answer is that we'd only do it where we strictly needed to, for example if further work was being carried out and even then only to the location required. Like other posters, we still use hand-drawings rather a lot (ahh, the joy of watching your last Rotring Isograph 0.18 nib break at 7pm on a Sunday night.......)