Collapsing model

Originally posted by bsbray11
So, yeah. Seriously, Smith and LB, you guys are demonstratably wrong. Check out parts 3 and 4 of the challenge. I would request you reconsider what you have suggested.

Hey leave me out of this, all I said is that the challenge thinks that toothpicks, cards, and pancakes, if they meet all five challenges, would be considered accurate representations of the tower by 911 research.

All I did was answer Lumos question.


BTW Lumos, where is this selective quoting? Msdos clearly posted all five challenges in his post.

bsbray - No I am still fairly undecided, you have to excuse me but I don't actually want it to be a conspiracy on this one - if it turns out to be 100% true then the consequences for us all are pretty dire! lol
If there are explanations which do not involve complete involvement of the authorities past turning a blind eye or being unprepared, then I'm pretty keen to find them. Some people might think that is odd, but I'm sure most can see where I'm coming from.
Does the model not show that a small mass can destroy a larger one though?

Originally posted by gordonross
The tower steel members were numbered and each piece could have been examined and the highest temperature it reached in the fire could have been verified. With that information much of the current debate would be irrelevant.
Instead we are left with a Nist report which has as a key part of its initiation sequence, a force, the very presence of which is disputed, [Lamont & Lane] followed by a collapse which they fail to properly investigate, discuss or explain.
Gordon.

Absolutely right, in the NIST report they have a rather insignificant number of columns all together with only a handful (if that) from fire damaged areas. You would have thought they would have been provided with more and they would have been selective enough to make sure they had a large number from the fire damaged areas - but they didn't.
I can understand them wantiungt oclear the area quickly, but given the circumstances and the severity of the situation you would have thought more care would have been taken to ensure that a definitive answer could be given, as in the plane crash. If it's possible to work out a toilet leaked and shorted out some wires from the wreckage of an airliner, thnen I'm sure they should have been able to give a definitive answer to what happened to the WTC.
It poses the question cover-up or cock-up?

Step 3: Build a structure as required by CHALLENGE #2 which, in the collapse process, will throw pieces outward in all directions such that at least 80% of the weight of the materials ends up lying outside of the footprint, but their center of mass lies inside the footprint.

I'd like to know how they came up to that 80%... I suppose that at WTC 1 and 2 that was at most about 50%, because I haven't seen any core columns outside of the footprint.. Well I might be wrong.



Footprint was a size of one toilet paper sheet..

About this big and position:



Some of stuff falled to floor, so i quess the center of mass is kinda close to footprint.

Umm... "at least 80% of the weight of the materials ends up lying outside of the footprint" means that it isn't enough that object's mass center is outside of footprint.

But I'll maybe continue working at those requirements. WTC-like collapse (where floors fall straight down and walls fall outside) would be good. I suppose it can be achieved when using polystyrene as floors.

Also notice that msdos is sexy.

Well video was kinda low quality... maybe that had a part on it.

Re: selective quoting

LeftBehind, I was referring to the exclusion of points 4 and 5 of the 911research challenge from your quote. Clearly, those are of utmost importance, as they disqualify any house of cards.

PS: msdos464, please answer my questions about the accurate representation of an actual building vs. your almost metastable construction. The energy required to fatally destabilize one of your floors is close to none. Also, regarding scaleability, I think it's mostly a matter of which parameter scales how. Linear, squared, cubic? Take your steel beam example: height - linear. Column cross-section - squared.




[edit on 28-2-2006 by Lumos]

PS: msdos464, please answer my questions about the accurate representation of an actual building vs. your almost metastable construction.

Do you mean this question:

There's only very little energy expense in this collapse: some friction between the cards and toilet paper/cd floors, little deformation of the cards and a bit of lateral KE towards the cards. Nothing gets shattered, nothing gets pulverized, nothing massive gets catapulted outwards. So, where's the analogy?

Analogy to what? Real buildings? There isn't... I build that card house mostly as reply to posts like this:

So the big question is: how far could 13 light floors get unto 97 heavier floors before being stopped dead in their tracks?

Common sense would hold that they wouldn't get very far.

At my building all floors were equally built, so they were equally strong.. each floor can support atleast the mass of 10 floors. Nevertheless that "building" collapsed from top to bottom... So - it isn't impossible.

That's what I wanted to demonstrate. Bigger building with polystyrene floors could do the trick.

Originally posted by AgentSmith
Does the model not show that a small mass can destroy a larger one though?

In certain circumstances, yes. Those circumstances mainly relating to there being no lateral resistance.

Originally posted by msdos464
I'd like to know how they came up to that 80%... I suppose that at WTC 1 and 2 that was at most about 50%, because I haven't seen any core columns outside of the footprint.. Well I might be wrong.

"They" is Jim Hoffman. It's from an interview he did and he actually says 80-90%. I'd say he's getting those figures from images like this:



The numbers may be exaggerated, but probably not by much. I'm glad you remember the bit about the center of mass still being within the footprint as well, since I'd forgotten that that was a part of the challenge. That requirement recreates the radial spread of damage. When the WTC fell, the debris was being ejected in all directions outwardly, radially, rather than mostly falling to one side as one might expect. That should be duplicated.

Originally posted by Lumos
PS: msdos464, please answer my questions about the accurate representation of an actual building vs. your almost metastable construction. The energy required to fatally destabilize one of your floors is close to none.

I think that has everything to do with the lack of lateral stability. If a card were even to be shifted a little in any direction, it would fall from those lateral forces rather than the weight of the cards from above.

If you were to hold a card straight up and drop a whole deck on it from a couple inches above, it would still stand as long as it had that lateral strength. If you didn't hold it, it would be hard to get the card to stand in the first place. That's where all of the instability comes from.

If challenge #4 can be met then we'd be good on that point.

Originally posted by msdos464
At my building all floors were equally built, so they were equally strong.. each floor can support atleast the mass of 10 floors.

Which is a purely vertical load. Your cards did not collapse from vertical loads, but from lateral loads on the sides of the cards.

So it's possible, but only when there's little to no lateral resistance. The WTC Towers were built to withstand hurricanes, so you're going to have to have to be able to carry some strong lateral loads in addition to being able to maintain vertical loads.

So if the cards, or the beams buckled, what was their lateral stability?

How much “lateral resistance” did the building have once the floor slabs connections with the exterior walls were broken?

Originally posted by HowardRoark
So if the cards, or the beams buckled, what was their lateral stability?

How much “lateral resistance” did the building have once the floor slabs connections with the exterior walls were broken?

With the WTC, an average of 75% of the columns would have had to have fallen on any particular floor to initiate a global collapse. Show that this ever occurred and then it will be relevant.

To show that that occurred, you will also have to show that steel was sufficiently heated so as to become equivalent to over 60% column loss in addition to the initial >15% loss of the impact damage.

Practically, you'll have to show that a majority of steel columns were glowing in broad daylight for what you're suggesting to have been the case.

Originally posted by bsbray11
With the WTC, an average of 75% of the columns would have had to have fallen on any particular floor to initiate a global collapse. Show that this ever occurred and then it will be relevant.

Where did you get this from? Please provide backup when you make statements like this.

Originally posted by bsbray11
To show that that occurred, you will also have to show that steel was sufficiently heated so as to become equivalent to over 60% column loss in addition to the initial >15% loss of the impact damage.

No. As I have repeatedly shown you in the other threads, all that was necessary was for the floor joists to fail. Once they began to sag, the exterior columns lost stability. The stability of the exterior columns from buckling is totally independent of their temperature. You continue to ignore this and try to divert the threads every time I bring it up.

Originally posted by HowardRoark
Where did you get this from? Please provide backup when you make statements like this.

In 2004 NIST has gave safety factor ratings for the core and perimeter columns (2.25 and 5, respectively), which were subsequently used, along with load ratings, to determine how much weight a floor could withstand on average before failure (at an average of 82 psf for floors 94-110 in WTC1, about 3,306 tons dead + live load -- assuming 200,000 ton buildings -- with safety factor ratings determining 11,075 tons would be needed on average for a single floor's failure), and how many columns would have to fail for a floor to no longer be able to withstand its loads (perimeter columns would've been able to hold 200% of their design load by the ratings, the core 135%, and failures to meet the design loads would require 80% perimeter failure and 55% core failure, or a proportionate average of 75% total column failure on any given floor whereas NIST asserts the core columns carried 60% of the total loads).

The figures are further detailed in this paper. NIST further states in this presentation that the WTC were only subjected to about 25% of their design live load capacities and about 1/5 of the design capacities of the perimeter columns. So, I guess that would just be that much more mass that would be required for the first floor to fail.

As I have repeatedly shown you in the other threads, all that was necessary was for the floor joists to fail. Once they began to sag, the exterior columns lost stability.

This would still have to amount to around 75% column failure. For ther perimeter columns alone, it would've taken more than that.

You haven't shown me anything to suggest this ever happened, and you can't, because it didn't. You need to show a majority of columns buckling on the the first floor to fail, before their failure, and then you further need to provide evidence that this was from the heating of the trusses.

Right now it's just a very crude and unsupported theory among many others.

[edit on 28-2-2006 by bsbray11]

all that was necessary was for the floor joists to fail. Once they began to sag, the exterior columns lost stability.

Leaving aside the floor joists for the moment, do you appreciate that the maximum force that the floors could possibly exert on the exterior columns, without significant movement of the core is limited to the mass of the floor transmitted through the remaining connections. This acts about the same moment as the 56 000 tonne mass [BZ] of the upper floors. Do you believe that the horizontal resolution of the floor mass, limited to only a few hundred tonnes at most, would be sufficient to affect the columns or do you believe that there was significant movement of the core.
Gordon.

How much “lateral resistance” did the building have once the floor slabs connections with the exterior walls were broken?

Sorry didn't realise this post was from the same author. Could you please give me a link or thread title for where you have detailed this previously,
Gordon

Originally posted by gordonross
How much “lateral resistance” did the building have once the floor slabs connections with the exterior walls were broken?

Sorry didn't realise this post was from the same author. Could you please give me a link or thread title for where you have detailed this previously,
Gordon

www.abovetopsecret.com...


www.abovetopsecret.com...


www.abovetopsecret.com...


I went over this in another thread also.

The cliff notes version is this:

The impact knocked the fireproofing off the floor trusses (at the ceiling height).

The fires quickly heated up the exposed trusses to the point of failure.

The floors sagged, depriving the exterior columns of lateral stability, and effectively lengthened the columns.

The columns were thus more susceptible to buckling failure.

Originally posted by HowardRoark
The impact knocked the fireproofing off the floor trusses (at the ceiling height).

I have been leaving these 911 threads alone because the loss to the FDNY was just too much, and I get a little excited and my blood pressure goes too far up so I try and not to comment.

Howard my life is dealing with fire. It can transform anything given enough fuel and O2. Ive seen it destroy a lot of structures, but I cannot buy that those buildings fell like they did on 911 due to fire.

You said in your above quote "The impact knocked the fireproofing off the floor trusses" and this is what brought me out to comment. The way those buildings were built, you cannot knock the fire proofing off the oppisite side of the elevators. No way buddy, it didnt happen that way, just have a few of the columns not fail and it wont fall like it did. You have to know that Howard. Look at flight 175, I bet it didnt even knock off all of the fireproofing on the side of the building the aircraft penetrated.

There just was not enough fire there Howard... I have seen house fires burn more intense than those buildings did. Let alone the fact that the fireproofiing especially on flight 175 could have exposed all 47 columns.

Originally posted by HowardRoark
The cliff notes version is this:

The impact knocked the fireproofing off the floor trusses (at the ceiling height).

Were any real-world tests conducted to quantify the projected loss of fireproofing from the impact, or is what you posit based on NIST computer-produced sliding-scale guesses, as was the case with the fires? Please describe the testing method. Can you also please explain, in your own terms, why in recent years the effects of fireproofing on steel composite structures has been gradually re-evaluated and deemed to be exaggerated, and furthermore why the U.K's globally respected Arup Fire Engineering openly stated that NIST's conclusions regarding the role of inadequate fireproofing in the collapse of the WTC towers was patently wrong?

The fires quickly heated up the exposed trusses to the point of failure.

Please provide evidence, both physical and computational, to support your statement. Temperature excursion tests conducted on the affected truss steel, and an energy assessment of the fires encompassing heat dissipation faithful to the actual conditions will suffice.

The floors sagged, depriving the exterior columns of lateral stability, and effectively lengthened the columns.

Please provide evidence of sagging floors and explain how weak joist connections, weak enough to facilitate "runaway global collapse" of the entire structure with negligible resistance, were simultaneously strong enough to hold so as to pull entire sides of the building inwards. Also please explain, in your own words, what effects thermal expansion of the joist assemblies would have on the tension forces acting on the exterior columns as a result of any sagging floors.

The columns were thus more susceptible to buckling failure.

Have you produced load-redistribution and appropriate DCR re-calculations to show that buckling of the exterior columns to the extent observed would exceed the redundancy of the entire structure? If so, please repeat them here or provide a direct link to where you have posted it before.

[edit on 2006-3-1 by wecomeinpeace]

Originally posted by bsbray11

Originally posted by msdos464
I'd like to know how they came up to that 80%... I suppose that at WTC 1 and 2 that was at most about 50%, because I haven't seen any core columns outside of the footprint.. Well I might be wrong.

"They" is Jim Hoffman. It's from an interview he did and he actually says 80-90%. I'd say he's getting those figures from images like this:

...

The numbers may be exaggerated, but probably not by much.

Well first we should know how big was the core's part of the tower's mass. I believe, that most of the outer walls ended up outside of the footprint, but core didn't (because tower didn't fell). We don't even know how many percentages of floor's concrete was pulverized! (atleast I don't..), so it's hard to estimate how much stuff was left inside the footprint.

BTW, WTC towers continued like 10 - 20 meters underground, right?

Originally posted by HowardRoark
The stability of the exterior columns from buckling is totally independent of their temperature. You continue to ignore this and try to divert the threads every time I bring it up.

But, the stability of the exterior columns depends on floor joists not failing. Which is in direct proportion to the temperatures talked about previously. In your senario, the columns buckled from the gain in length due to floor joists failing. The floor joists failed due to strength loss from temperature. Hence, temperature has a direct affect on the buckling strength of the columns.

Originally posted by msdos464
BTW, WTC towers continued like 10 - 20 meters underground, right?

Yeah, there was a deep concrete foundation to support the weights of the buildings.

I see a WCIP post!

Yay,

huzzah to wcip

Sorry, am I getting in this right.. Do you see the WTC buildings as having been a solid object with no significant weakpoints?