WTC7 collapse on Sep 11-2001

Jocksereire wrote: »

How can anyone seriously design a building for a plane impact and NOT consider the fire potential and the fuel carried by the plane?

The technology and mathematics to model fire effects in buildings didn't exist at the time.

Ergo, we can say with surity that the effects of fire were not modelled at design time.

As it is, there is uncertainty about quite what was modelled. Some say it was a model of a slow-flying, mostly-out-of-fuel 707. Others say that it was a fast-flying, fully fuelled 707.
Some say it was a design issue. Others say it was a calculation performed post-design which happened to give the desired answer.

What we know for sure is this:

1) Whatever modelling was done has been lost. Thus, it is impossible to verify what was modelled and if that modelling was correct
2) Nothing was modelled which could not have been modelled at that time. This includes fire effects.

NIST themselves say "The initial jet fuel fires themselves lasted at most a few minutes" hence any fire after a few minutes is what? Nothing more than an office fire.

The nature of how both start and spread is completely different, and this has an effect on things.

This is why its not exactly "nothing more than an office fire"...but you'd know that, given that NIST explain the details in that report you're familiar with.

Also for the person who believes that total collapse was inevitable after initiation can you tell us why?

In a nutshell - because there was nothing above ground-level with sufficient resistance to stop 10+ stories of mass falling.

Jocksereire wrote: »

Ok lads. Firstly both planes fuels tanks were one third full so saying that the 767 held more fuel than a fully loaded 707 is incorrect.

Not what I said...

What I said was...The 757's are bigger, heavier, faster and hold more fuel. (should have been 767's, which are even bigger, heavier and faster)

Basically the mass of the plane was greater and therefore was going to cause more damage than was originally allowed for. The amount of fuel was only going to make this worse.

I'm not a structural engineer but from using my own eyes I can see that buildings brought down by controlled demolition have been set to fall in a similar way. So I know it could collapse this way. The weight of the tops of the buildings falling would have a similar effect to blasting out floors and letting the builds own weight take it down in controlled demolition. So just by making simple comparisons you can see it could have easily happened as the official reports says (Towers 1&2). I have no way to know for sure if that’s what actually happened, I’m just not assuming there’s a big conspiracy because I’d like there to be one.

Jocksereire wrote: »

ok thanks for clearing that up for us all. Dropping weights on your feet, of course.

Right i really dont want to discuss this all again lads im sorry, i shouldnt have replied to any posts in the first place but i find myself getting hooked every time. Mainly for the reasons N_O points out. im tired of going round in circles.
All i want to see is a reinvestigation.
I take it from the silence to my question that none of you think a reinvestigation is necessary and you believe the 911 comission report is true?

for me this is a great shame but who really gives a toss

I have no way to know if the official report is correct or not. But after reading a lot of stuff about the whole event I don't really see the point for reinvestigation. Some questions cannot be answered, the building are gone. I don’t doubt they may have covered up some of what they learned. But at the end of the day the likelihood is we'd get to learn that the American government were even more incompetent than we thought, what would that help? Too many people do not want to believe things happened the way the report says. For me the conspiracy doesn’t stack up, I find many many more questions in the conspiracy than I do in the official report. I can’t be sure either way but my opinion is the official report is within reason believable.

Jocksereire wrote: »

so they built it to withstand a plane crash and did not take into account the fuel?? I disagree with you here.

Both you and I can turn up no shortage of quotes attributed to the relevant people to show that there was some design studies regarding a plane-crash scenario.

I can also provide quotes, from the same people (e.g. from Leslie E. Robertson saying that they did not take the ensuing fires into accoun:

To the best of our knowledge, little was known about the effects of a fire from such an aircraft, and no designs were prepared for that circumstance. Indeed, at that time, no fireproofing systems were available to control the effects of such fires.

There is already uncertainty about what exactly the crash-scenario studied was (as I've pointed out). Those most closely associated with it claim it was a low-speed, low-on-fuel, lost-in-fog situation, like what happened with the Empire State Building. Others claim that it was high-speed, fully-fuel laden. I'm not too concerned in those details (I'll address why shortly), but what we can say is that the existnece of this study is accepted despite there being no copy of the study known to exist because numerous involved parties have verified that yes, a study of some sort was done, and yes they (the parties commenting) were involved, or can verify that others were involved.

Those self-same people say that they are unaware of any studies done to process the ensuing fire and - like the study they do remember - there is no actual copy of such a study.

We have people saying "no, we didn't do that", and we have no study to prove them wrong.

On what basis, therefore, can one reasonably conclude that the study must have been done, or that its reasonable to assume it was done?

But lets assume you're right for a second. Lets actually go with the idea that the study was done and it said that the ensuing fires would not collapse the building. What proof is there that the study was correct? There is none.

fact is according to NIST it lasted at most a few minutes....twist it all you want its still only an office fire afterwards

I'm not questioning that the fuel byurned off in a few minutes. I agree that it should have, and that it did. The point I was making is that I would distinguish between "a fire fueled only by office materials" and "only an office fire". In an office fire, you have a point of ignition, followed by a "spread pattern". As the fire progresses, it will consume material in an outwards pattern...the fire is at its strongest at the perimeter, and will die down in the interior (on account of having burned all the available fuel) sooner.

In the cases of WTC 1 and 2, the jet fuel meant that there was no single point of ignition. Thus, the spread of fire and its ensuing burn-pattern were completely atypical for "only an office fire". The materials available to burn....here we are again in agreement....they would be exactly the same as in any other office building which catches fire.

not sure what youre saying here. are you saying a discussion on a 707 compared to 767 is pointless?

In effect, yes.

The building withstood the impact. I believe we - and everyone else here - all agree on this. It was not the impact alone which caused the buildings to fail. You say so, I say so. NIST says so. Everyone interested (except no-planers) says so.

So what is the relevance of discussing the differences?

Its relevant to look at the design of a 767 with respect to modelling the impact. The design of a 707, and the differences between them...what can it possibly tell us?

The building design may have been built to withstand nothing larger than a Cessna. It may have been designed to withstand an asteroid impact. It doesn't matter because when the design was put to the test, we know that only the outcome is relevant...and we know that the outcome was that the impact did not knock either tower.

Incorrect there was. coming from someone who always looks for evidence to back their claims up ....."in a nutshell" is shocking and hypocritical to say the least

In my case, at least, it was more a case of "running for a train, so no time to address the point in detail". I'm sure you have an equally valid reason for your equally-lacking-in-detail comments, so lets move on to supplying that missing detail rather than flinging mud, shall we?

The tower's construction consisted of multiple mutually-reinforcing design concepts. The main box-columns primarily gave vertical support. However, they in turn relied on the weight of the supported floors to keep them in place...and both the floors and the central columns relied on the curtain wall to give additional lateral stability. The curtain wall, in turn, relied on the floors for vertical stability.

Now...if one floor fails, where does its weight go? It (obviously) lands on the floor below. Ignoring the extra energy that momentum adds, we know that the box-columns and outer wall aren't being asked to support any more weight. So there's no problem...right? Well...maybe, but we need to look at that...

They may only need to support the same weight, but they are being asked to support a different weight distribution. Just think about that for a second. If you can suspend a 20kg from your left hand with your left arm outstretched, and you can do the same with your right arm....does that mean you can suspend 40kg from one arm, leaving the other free?

When failure occurred, it was ultimately because the support-mechanism for one floor failed, resuling in a lower floor being asked to carry too much weight, resulting in its collapse. This was exacerbated by additional factors - e.g. the collapse pulled the curtain (the 'perimeter columns') inwards, further weakening the load-bearing capacity of the floor immediately below the point of failure and weakening the support for all floors above the point of failure, which was sufficient (when added to the existing damage) to cause that entire chunk to collapse.

Once that happened...game over. There was no way for the lower section to "catch" the upper section.

There's been plenty of math looking at this. Some says there wasn't enough energy to "override" the proven load-bearing capabilitiy, but doesn't address that the load-bearing capability is dependant on load distribution.

Jocksereire wrote: »

Dr. James Quintiere?

I didn't get a chance to address this point yesterday.

Dr. Quintiere's is indeed calling for a peer-review of NISTs work. I'm not aware of his stance on teh reviews already carried out as part of the project, but either which way...lets look at his case as he's beyond a shadow of a doubt qualified to offer an opinion.

Dr. Quintiere maintains that two aircraft crashed, one into each of the towers. He maintains that the damage from impact coupled with the effects of the ensuiong fire caused the buildings to collapse. He has not criticised the manner in which NIST obtained their evidence, nor the evidence itself.

Where his criticism lies is that he believes NIST did not consider the full range of possibilities as to how damage-and-fire could have led to collapse. He believes they underestimated the amount of combustible material which fed the fires, which in turn led to an underestimation of the fire intensity, which in turn led to a sligthly different collapse mechanism.

Quintiere's concern is that there are additional lessons to be learned, concerning the behaviour of office fires and their containment. If I remember correctly, his figures (which use 3x mroe combustible material...quite a difference) show that the damage and fire combined would cause collapse even if the fireproofing was not damaged.

Quintiere may also have made suggestions that the fireproofing wasn't damaged to the extent claimed, or that his model allows that it may not have been, or something to that effect.

He supports the idea of a peer review of NISTs work (which is not an independant investigation of the events of the day), because he believes that such a review would resolve the question of whether it was damage-and-fire-as-per-NIST, or damage-and-fire-as-per-Quintiere. His reason for doing so is, to my understanding, that his model would require more stringent fireproofing standards.

Unfortunately, even in his own work, Quintiere doesn't go into much detail about why he believes the figure of 20kg/m3 is too low, and why the figure of 60kg/m3 is more credible. NIST, if I recall correctly, did explain how they arrived at their figure.

What's important to remember here is that Quintiere is arguing that the fires were worse than NIST claimed. He agrees that the buildings still collapsed from damage-and-fire. He agrees with much of what was done and why. He agrees broadly with the findings, but thinks that there is important nuance in the detail that merits a peer review. If anything, his argument is that NIST took an overly conservative view of the effects of the fire and damage, and although they still concluded that the building should collapse, their detail is not entirely accurate.

I think Quintiere has a point worth following up on. I think that - to a point - its fairly academic as to whether he or NIST are correct (in the sense that both agree that big frickin' planes impacted big frickin' buildings, resulting in big frickin' fires, and culminating in big fricking' collapses)...but rather that if his model stands up to analysis that it should also be used as a guide for future building codes.

Where I would draw the line, however, is suggesting that Quintiere is right before a peer review (or other third-party review of the issue) is carried out. I most certainly wouldn't agree with suggesting that Quintiere is right and that we can ascribe motive as to why NIST is wrong.

I take it from the silence to my question that none of you think a reinvestigation is necessary and you believe the 911 comission report is true?

There are unquestionably areas of the 911 investigation which bear further scrutiny. There was suggestion of some testimony (FAA or Air Force..can't quite remember) being deliberately misleading or downright wrong, which I'd like to have looked at. There's Quintiere's call for a peer-review, based on what Iv'e described above. But in such cases, I support the specific allegations being looked at to see if they have merit. If they have merit, then the specific areas should be looked at to find out if the allegations are correct. Only then, if the allegations are correct, and the ensuing conclusions damning enough, do I believe that there is even the remotest of grounds to thing about re-examining the entire thing.

Sadly, I believe that the cries of 911 was an inside job have done more than anything to ensure that no such issues will be re-opened or re-examined. As I've said many times on this forum (and elsewhere), if I wanted to hide somethng from scrutiny, I couldn't devise a better smokescreen to hide the truth than the one which Jones, Avery, Griffin et al have erected and profited from.

cooperguy wrote: »

As a guy who has a BSc in Material Science (well a few months away from it) there was never anything inconcievable about that happening. People have known the structural and mechanical properties of steels for quite a while now believe it or not

One would have to wonder at the thought process that concluded steel-supported buildings could not collapse due to fire but that the steel supporting those buildings needed fire-protection all the same.

Good luck with the BSc.

whiterebel wrote: »

On the subject of WTC7, I can't really see any way anyone can dispute this building was brought down intentionally....

Whereas I can't see how anyone can clam it was. Its pretty-much as Nick put it earlier, I guess.

As to the question of how, didn't Silverstein's company build WTC7?

Nope, They didn't. WTC7 was designed by Emery Roth & Sons, and constructed by Tishman Realty & Construction.

Seeing as all Skyscrapers are supposed to have a finite lifespan, is it inconceivable that it was wired from day one?

Do you mean to ask if it is inconceivable that the building was prepped for demolition from day 1? Yes, it is inconceivable, given what prepping a building for demolition involves.

The only way that WTC7 could have been controlled demolition (prepped from day 1 or not) is if it wasn't standard CD.This is necessary to explain all of the things that are different to every example of CD which can be provided.

However, if it wasn't standard CD, then the entire argument of "It looks exactly like..." falls apart in the first place.

We end up with a line of reasoning which says that it looks exactly like we think something we've never seen would look like!!!

At the same time, we're not allowed even ask what WTC7 collapsiong from damage-and-fire would look like, nor suggest that it could/would look like what we saw.....because we've never seen anything that we can compare it to!!!