WTC Visual Explosives ('Squibs')

Originally posted by Fiverz

I asked the engineer about it and he said the only way a building of that magnitude would fall would be with pre-calculated cuts in beams and supports and even detonating small charges weeks ahead of the demo. He explained to me that the reason I couldn't go any closer (hehe I was 17 and anxious to get up and close) was that the structure had weakened so much from all the pre-demo work that any part of it could really fail at any time. He said the actual "demo" was nothing more than clean up to chop the building into small enough pieces to remove economically.

So how come if it takes that much work and structural weakening, of a building of only 34 floors, to demolish it , that the twin towers could fall so easily from one impact high up.Although there is no precedent to 9-11, You would when thinking about it expect them to topple sideways or collapse on itself in a different, far less smooth, manner.

I would think there are technologies that the American government has regarding explosives that we can't even imagine. Small, easily placed divices, with maximum efficiency for bringing down structures.

I at first deemed the demo theories discrediting to the overall 9-11 truth cause..but to be honest I don't think it is impossible at all. Official details like the recovery of a highjackers passport in the burning ruins of the WTC buildings I would say are less believable...Siesmic readings back up an explosion directly prior to collapse too as far as I am aware......I mean apparently WTC7 had undercover CIA offices inside! That building fell into it's foundations also!....with another weak and not fully concluded explanation from FEMA

[edit on 28/6/2006 by earthtone]

Originally posted by Masisoar
Even though it's a bit off subject and belongs in demo threads, the construction of the WTC, as Howard has pointed out sometimes is unique. I even firmly believe you wouldn't need too much demo work on a building that size to bring it down, just have to cause a great enough force from above to take down the rest of the building below.

Just remember the WTC 1 and 2 were tubular. Who knows about the process though of how the building was rigged over what time span, as most of the files pertaining to anything like such were in the WTCs and thus being.. lost.

But let's jump back to the squib subject here, it's indeed interesting.

Just one comment so the thread doesn't get derailed.

I think you're right that without question the towers were of unique construction and would have necessitated a different demo plan. It may have have taken less prep work and charges---or it could have taken more. Who knows? But one thing for sure, it would have taken SOME. and that means the process needed to rig and that process is the same--strip walls--cut beams, etc. You just can't make that reality go away.

Originally posted by Masisoar
Yeah but at that type of air pressure in the building Howard, if it was enough to knock that guy off his feet, wouldn't it cause substantial damage to the windows and cause a lot of blow outs on a global scale rather than just a few isolated incidents on the lower floors?

My 2 cents.

Why? In the example that Howard provided the air pressure was ejecting down a still sealed stairwell possibly concentrating the effect.

In the building overall this may not be true. We'll never know the dyamics involved as it collapsed. Its possible that as the floors pancaked the exterior facade still stood for an instant, but there was no longer a seal between floors and a great amount of the pressure wave could escape upward and over the facade walls ejecting debris and dust along with the pressure creating the "mushroom cloud". This would have relieved much of the pressure and only the weaker window areas may have failed producing only random pressure "squibs".

One thing still puzzles me though. How can anyone look at a controlled demo like the clip posted and see ANYTHING that resembles the process of collapse at the towers?

[edit on 28-6-2006 by Vushta]

An excuse for the windows to be weak is slightly viable, but why would the the air pressure be concentrated in the stairways and not in the rest of the floors provided they have open air with the stairways, the stairways weren't sealed shut, you had masses of people trying to go down them the whole time.

If you have a force that great, of air rushing down through the stairways, and out the lobby area, you're still going to get compression on the floors exposed to the stairway or that are open to anything accessing the upper floors that are collapsing, if its great enough to cause that much ferocity in the lobby, then it would apply too on the floors exposed.

There were shafts that came down the building and up the building to provide air weren't there, and every floor had access to them.. hmmm?

Originally posted by Vushta

Originally posted by Masisoar
Yeah but at that type of air pressure in the building Howard, if it was enough to knock that guy off his feet, wouldn't it cause substantial damage to the windows and cause a lot of blow outs on a global scale rather than just a few isolated incidents on the lower floors?

My 2 cents.

Why? In the example that Howard provided the air pressure was ejecting down a still sealed stairwell possibly concentrating the effect.

In the building overall this may not be true. We'll never know the dyamics involved as it collapsed. Its possible that as the floors pancaked the exterior facade still stood for an instant, but there was no longer a seal between floors and a great amount of the pressure wave could escape upward and over the facade walls ejecting debris and dust along with the pressure creating the "mushroom cloud". This would have relieved much of the pressure and only the weaker window areas may have failed producing only random pressure "squibs".

One thing still puzzles me though. How can anyone look at a controlled demo like the clip posted and see ANYTHING that resembles the process of collapse at the towers?

[edit on 28-6-2006 by Vushta]

The stairway incident shows that there were atmospheric pressures inside the core. There were doorways from the core into the halls which are the only way for that pressure to get from the core to the windows.

In Howards description 3 inch thick pieces of glass were flying through the air in the stairwell. From the start this doesn't make sense because the glass is between 60 and 35 feet from the core wall and the stairs are on the inside of the concrete core wall.

The notion of a "piston and cylinder" type relationship between the floors "pancaking" and the perimter wall is not at all credible. The amount of solidity needed to do that does not exist in the image of the event which shows heavy particulate with considerable velocity expanding horizontally.

That image cannot be a collapse. Collapses are of solid pieces falling in a jumble to the ground whereupon they break further. What we see is completely broken, pulverized or reduced already. You cannot make that reality go away and it can only be created with optimally placed and distributed high explosives.

Altogether meaning that the building was built to be demolished if we see what we see in the above link.





[edit on 28-6-2006 by Christophera]

Originally posted by Christophera
The stairway incident shows that there were atmospheric pressures inside the core. There were doorways from the core into the halls which are the only way for that pressure to get from the core to the windows.

Christophera, I thought that you claimed to be familiar with how buildings are designed and built.

Plenum
From Wikipedia, the free encyclopedia


Plenum spaces in buildings are spaces for air circulation in air conditioning systems.

There are usually two main systems, the supply and return plenum. Toilet exhausts are a separate system.

So Howard, your professional take on this:

Since all floors had access to the main air flow systems that ran throughout the World Trade Center, the same access the lobby had, the same access the regular floor had. And to mention some floors were vented to the stairway that was open down by the lobby.

If there was enough pressure to blow out one window, why not any others? Was the air pressure that air tight throughout the whole system to where there was enough air compression as it collapsed in everyfloor to cause those couple of windows to blow out? Even AHEAD of the collapse? Even as it was getting vented out through the lobby?

Was the building that air tight to allow such pressure? I dun shink so.

The best and most expensive hurricane resistant windows/frames for commercial use today are rated to 140-150psf. That's about 1psi. (source)

Let's imagine for the sake of conservative argument that the towers were all retrofitted with these modern, super-tough windows.

A post of mine on another forum:

Since PV is a constant, if you half the volume, you double the pressure. For example, if you pressurize just one WTC floor worth of air into another, the air pressure across the entire target floor will rise to 29.4psi, an overpressure of 14.7psi. In this instance all of the windows on a floor would easily and rapidly explode outwards, well before this pressure level was reached. Only if the rate of air being released by the ruptured windows was equal to or more than the air being pumped into a floor could the pressure remain at or under 1.0psi breaking only a few windows. If the pressure is unable to be alleviated fast enough by the created aperture, then the overpressure on that floor will continue to rise beyond 1psi, that is, beyond the pressure resisting capabilities of all the other windows, and hence all the windows on the floor would blow out. But since the aperture area of the stairwells, elevator shafts, and HVAC shafts allegedly feeding the air in was much greater than the aperture area of the ruptured windows releasing the air out, and the floors were collapsing at the rate of about 10 per second, this would seem to be impossible.

We can calculate the maximum rate (choked flow) of gaseous release from a ruptured, pressurized vessel using an established gas dynamic equation:



Where,
m = discharge rate, kg/s
Cd = discharge coefficient = 0.62 (assumed ideal, conservative estimate)
Ah = aperture area = 7.26m^2 (assuming 3 windows of a floor were blown. The windows were roughly 3.66m x 0.66m = 2.42m^2)
P0 - vessel pressure = 101352.9279 Pa
p0 = gas density = 1.204kg/m3
gamma = ratio of specific heat = 1.4 for air

Which gives m = 1076.826kg/s

Each floor of a WTC tower was 63m x 63m x 3.66m = 14,526.54m^3 volume. The density of air at STP is 0.001204 g/cm^3 = 1.204 kg/m^3, so that's 17,489.3kg of air on one floor.

1076.826/17,489.3 = 6.16%

So 6.16% of the total air on a floor could be discharged from our aperture per second, and that is assuming the maximum physically possible discharge velocity, which is Mach 1. However, just one single floor's worth of air pressing into another means that there will be a 100% increase in the amount of air in the target floor. Even one tenth of the air from one floor pressing into the other will create a 10% increase in moles of air (ignoring pressure increase related to temperature increase), or 1.47psi rise in pressure, again beyond our super-strong, circa 2006, hurricane resistant windows' capabilities to withstand. Since the rate of floor collapse was about 10 per second, we can see how the "pressure release" theory is unsupportable. If the squibs were a result of some syringe-like pressure effect, every single window in the affected floor would be expected to blow out.

I'm just plugging and playing with the above gas equations and my maths is atrocious, so someone please correct me if I'm wrong somewhere. In fact gas dynamics is Val's area of special expertise, so maybe she can correct me.

Regardless, I believe the reasoning is sound. The maths is just numerical confirmation of that. The syringe squib theory implies that the overpressure on a floor containing 514,188 cb ft of air rose instantly to 1psi, and then suddenly stopped, levelled out, and was alleviated by air rushing out of three or so 2ft x 12ft windows. Intrinsic to this train of thought is also the premise that this amazingly constant just under 1psi of overpressure is still enough to create long jets shooting out 50ft laterally from the building at enormous speeds.

And I doubt the WTC towers had windows that were as strong as I'm assuming.

Were cutting charges responsible for the squibs? Impossible to say. There's a curious difference in character between different squibs, some being constant jets UNlike observable squibs in recorded CD, and some being single puffs very reminiscent of same. It is conceivable that localized explosives triggering off in close sequence could create such streams as one expulsion replaces the next a micro-second later...but I'm just speculating.









[edit on 2006-6-28 by wecomeinpeace]

Originally posted by Masisoar
An excuse for the windows to be weak is slightly viable, but why would the the air pressure be concentrated in the stairways and not in the rest of the floors provided they have open air with the stairways, the stairways weren't sealed shut, you had masses of people trying to go down them the whole time.

If you have a force that great, of air rushing down through the stairways, and out the lobby area, you're still going to get compression on the floors exposed to the stairway or that are open to anything accessing the upper floors that are collapsing, if its great enough to cause that much ferocity in the lobby, then it would apply too on the floors exposed.

There were shafts that came down the building and up the building to provide air weren't there, and every floor had access to them.. hmmm?

Thats a good point, but then we're faced with arriving at an applicable quanity of force.

How much force is need to knock a man off his feet while decending a stairs? We've all seen the weather forcaster foolishly standing out in a hurricane of 130 mph having a difficult time standing. How well would he do if he were decending stairs and not just doing his best to root himself to one spot?
Is it possible that windows rated to withstand hurricane forces could remain intact while a man is unable to stand while decending stairs?

There were shafts that came down the building and up the building to provide air weren't there, and every floor had access to them.. hmmm?

were they clear and functioning or blocked? We don't know.

Originally posted by Vushta
...strip walls--cut beams, etc. You just can't make that reality go away.

How is it possible for you to know with 100% certainty that you would need to cut beams? Sure, in most demolitions beams are pre cut, but how do you know FOR SURE that there is no other way?

Same with "stripping walls". How are you 100% CERTAIN that this would be necessary?

You DEMAND 100% PROOF out of every other poster even though you know it is not possible, demand the same of yourself.

Originally posted by Vushta

Originally posted by Masisoar


There were shafts that came down the building and up the building to provide air weren't there, and every floor had access to them.. hmmm?

were they clear and functioning or blocked? We don't know.

A good point. The shafts would have had fire dampers with fusible links at each floor. It is possible, that the fireballs that blew down the core shafts could have caused some of those links to melt, and thus shut the fire dampers on various floors.


[edit on 28-6-2006 by HowardRoark]

Originally posted by HowardRoark

Originally posted by Vushta

Originally posted by Masisoar


There were shafts that came down the building and up the building to provide air weren't there, and every floor had access to them.. hmmm?

were they clear and functioning or blocked? We don't know.

A good point. The shafts would have had fire dampers with fusible links at each floor. It is possible, that the fireballs that blew down the core shafts could have caused some of those links to melt, and thus shut the fire dampers on various floors.


[edit on 28-6-2006 by HowardRoark]

Fire dampers are meant to block smoke and flames, not pressure.

Are you familiar with the operation of first generation fire dampers? They are only held shut by a weak spring or gravity...

The dampers would have been forced open by far less pressure than would be needed to blow windows out.

This argument is just meant to confuse. Fire dampers made the squibs? whatever.

[edit on 28-6-2006 by Slap Nuts]

And rather, if you see the squib photos, does it look more like air, or something more dusty coming out?

Originally posted by Slap NutsFire dampers are meant to block smoke and flames, not pressure.

Are you familiar with the operation of first generation fire dampers? They are only held shut by a weak spring or gravity...

The dampers would have been forced open by far less pressure than would be needed to blow windows out.

This argument is just meant to confuse. Fire dampers made the squibs? whatever.

[edit on 28-6-2006 by Slap Nuts]

The WTC was designed and built in the late 60’s early ‘70’s, that is hardly “first generation.”

Based on building codes, the fire dampers would have been rectangular steel curtain types.

This type of damper was in widespread use well before the construction of the WTC.

It is designed to block the airflow through the duct. The curtain drops down between two guide rails. Air pressure is not going to force it open again.

So are you saying the fire dampeners blocked air flow to the floors that had the supposed Squibs?

Originally posted by HowardRoark

Originally posted by Slap NutsFire dampers are meant to block smoke and flames, not pressure.

Are you familiar with the operation of first generation fire dampers? They are only held shut by a weak spring or gravity...

The dampers would have been forced open by far less pressure than would be needed to blow windows out.

This argument is just meant to confuse. Fire dampers made the squibs? whatever.

[edit on 28-6-2006 by Slap Nuts]

The WTC was designed and built in the late 60’s early ‘70’s, that is hardly “first generation.”

Based on building codes, the fire dampers would have been rectangular steel curtain types.

This type of damper was in widespread use well before the construction of the WTC.

It is designed to block the airflow through the duct. The curtain drops down between two guide rails. Air pressure is not going to force it open again.

Where is your source for the fire codes in NYC at that time?

Where is your source for the usage of this type of damper in the WTC buildings?

You make statements as if they are fact then link to a Purdue paper?

Show me a document from New York and the WTC.

Originally posted by HowardRoark
The WTC was designed and built in the late 60’s early ‘70’s, that is hardly “first generation.”

Based on building codes, the fire dampers would have been rectangular steel curtain types.

This type of damper was in widespread use well before the construction of the WTC.

It is designed to block the airflow through the duct. The curtain drops down between two guide rails. Air pressure is not going to force it open again.

WRONG HOWARD.

WTC1 and WTC2 were NOT required to have dampers much less the type you INSIST they had.

Installation of combination fire/smoke dampers in HVAC ductwork, which was not required in WTC 1 or WTC 2, may have acted to slow the development of hazardous conditions on the uppermost floors of the building, but would likely not have had a significant effect on the ability of occupants to egress the building due to the impassibility of the exit stairways.

From your best friends at the NIST: wtc.nist.gov...

You always post as if you are posting fact but you are flat out busted this time.

[edit on 28-6-2006 by Slap Nuts]

No, if the the fire damplers were shut, they would have blocked the air flow out into the other floors.

It's all a moot point anyway. The conditions inside a collapsing building can not be determined with any certainty, so there is no point in arguing what air pressure would have been on any given floor. We know that there was massive air movement within the building envelope as well as out the top of the collapse zone. Would this have been sufficent to have caused the "squibs?" Absolutely.

It is impossible to prove otherwise. Therefore you have to accept the possibility that they were simply caused by the movement of air within the building.

Comparing the two possibilities, explosives, or air movement, air movement is by far the simpler and more logical explanation.

Originally posted by HowardRoark
No, if the the fire damplers were shut, they would have blocked the air flow out into the other floors.

It's all a moot point anyway. The conditions inside a collapsing building can not be determined with any certainty, so there is no point in arguing what air pressure would have been on any given floor. We know that there was massive air movement within the building envelope as well as out the top of the collapse zone. Would this have been sufficent to have caused the "squibs?" Absolutely.

It is impossible to prove otherwise. Therefore you have to accept the possibility that they were simply caused by the movement of air within the building.

Comparing the two possibilities, explosives, or air movement, air movement is by far the simpler and more logical explanation.

There were NO FIRE DAMPERS in WTC1 or WTC2 though you stated it as fact above.

The NISt said it so it MUST be fact.

wtc.nist.gov...

Originally posted by HowardRoark
Comparing the two possibilities, explosives, or air movement, air movement is by far the simpler and more logical explanation.

Not really Howard.

I find it illogical that in a universal collapse that the pressure would only blow out a few windows if it was the collapse causing the pressure. The squibs seem illogically localized and in illogical locations to have been caused by collapse induced pressure.

I also find it illogical that pressure would be building up even though the top of the buildings were wide open. Ever squeeze an open beer can?

I also find the distribution of the air pressure/squibs to be illogical given a symmetrical collapse.

Finally, if your damper lie were true, how would the pressure have transfered through the closed dampers to floors far below the collapse zone? You do proclaim them to be "pressure proof".