BBC Reported Building 7 Had Collapsed 20 Minutes Before It Fell

This company sells a very inexpensive experiment we can all try. I believe the basic principal can be recreated.

http://www.hasbro.com/jenga/

 

Did you watch the video I e-mailed you, Skip?

The fires were not hot enough to melt steel, much less weaken it to the point of collapse while bringing down the entire 47-column core with it. The plane hitting the building was not even factored into the collapse in the NIST report or by the 9/11 Commission. The primary cause, according to them, was fire, which FEMA even admits in their report has a "low probability" of causing the buildings to collapse.

Would anyone like to explain the explosions that were heard by people in the buildings leading up to the collapses? Several of the firefighters who were there have said that secondary devices were planted within the buildings. Are they lying, or just delusional? Firefighters were reporting bombs going off over their radios. Perhaps they were just hallucinating from all the carbon monoxide? How about the chilling testimony of WTC janitor William Rodriguez, who risked his life saving people from the building. He was one of the true heros of that day and the last person out of the building as it collapsed. Should we ignore his testimony of explosions going off in the sub-levels of the towers and throughout the entire building?

As far as flaws in the steel, I haven't heard about that other than in rumors from so-called debunkers (who in my opinion are full of nonsense and devoid of any facts). There is no evidence pointing to flaws in the steel, which was top-quality, commercial grade steel -- the best quality steel that was around at the time.

 

Is that supposed to be funny?

 

Again, if anyone wants a DETAILED analysis of the collapse of the Twin Towers and Building 7, here are some videos they need to check out:

911 Mysteries: Demolitions

http://video.google.com/videoplay?docid=-6708190071483512003&q=911+mysteries&hl=en

This is the best produced documentary to date providing evidence for controlled demolition in the collapse of the World Trade Center towers and Building 7.

9/11 Eyewitness (Hoboken Edition)

http://video.google.com/videoplay?docid=6498070204870579516&q=9%2F11+Eyewitness%2C+Hoboken&hl=en

While this isn't as well-produced as the former, it offers more detailed insight into the collapse of the towers and WTC-7, including the possible use of thermonuclear devices in the basements of each building.

 

Steel starts sagging by creep at about one-third its melting point, or about 318 C. It loses half its yield strength at 550 C and 90% at 750 C. Its stiffness also decreases similar to its yield strength.

The loss of strength is substantial well below its melting point of about 1500 C. That's why structural steel needs fireproofing to reduce the chance of buildings collapsing. Wood and concrete can actually perform better than steel at elevated temperature. Steel-only structures can fail in an hydrocarbon fire within about 30 minutes if the steel is unprotected.

Fireproofing itself is not perfect. It increases the amount of time required to heat the steel. Structural failures can still occur with fireproofing if the fire burns long enough.

The fireproofing itself has to remain intact. Portions of the fireproofing of the towers were dislodged when the aircraft struck which rendered the steel unprotected. Dislodged sprayed-on fireproofing of the perimeter columns and floor trusses was seen in photos of the towers. People inside the towers also saw drywall littered about the stairwells and floors which served as the foreproofing for the core columns.

 

Not really.

The collapse of the towers WTC1 and WTC2 didn't initiate at the bottom but rather at the aircraft and fire damaged regions. The collapse also started with the upper section tilting toward the side that had the longest span floors between the core and perimeter and which had bowed-in walls.

WTC1 had the longest span floors on the south and north side. It tilted to the bowed-in south side. WTC2 had the longest span floors on the east and west sides. It tilted to the bowed-in east side and the side of the aircraft damage and fires.

That kind of failure mode agrees with sagging of the long span trussed floors due to the heat of the fires. The sagging caused the perimeter walls to bow inward and essentially took away one wall worth of support. It's a drawback of using inexpensive lightweight long span trusses to support long heavy floors. The complex shape of the trusses also makes them more difficult to fireproof, which is usually done with sprayed-on insulation which is vulnerable to spalling in an event such as a jumbo jet impact.

The south wall of WTC1 and the east wall of WTC2 were seen to be bowed inward in photographs and videos from numerous angles about 10 and 40 minutes before their collapse. The bowing worsened gradually with time as the fires burned and the metal weakened. Those in helicopters also noticed it and warned of a possible collapse. Those are the same sides that the upper sections tilted toward at the start of collapse, not surprisingly.

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Shaggie,

Why don't you explain how two 110-storey buildings fell at freefall speeds. The towers fell into the path of most resistance, yet the two towers collapsed at an average of just under 10 seconds. WTC-7 fell in approximately 6.5 seconds, which is the rate of freefall in a vacuum. This is something I have yet to see you debunkers try to debunk because you can't. A progressive 110-storey collapse was calcuated at being approximately 96 seconds.



The ONLY way the towers could have collapsed at the rate they did is if the floors were being blown out ahead of the collapse, which they were as seen in multiple video angles. There are visible explosions with metal beams being ejected hundreds of feet into the air with enough force to lodge into neighboring buildings. How do you explain this with your pancake theory?



Figure 5. Minimum time for the collapse, if nine of every ten floors have been demolished prior to the "collapse."



Figure 7. Minimum Time for a Billiard Ball dropped from the roof of WTC1 to hit the pavement below, assuming no air resistance.

 

Not really.


(c): Note that the top "block" begins to disintegrate
before the damaged zone starts to move downward.

 

The towers didn't fall at free-fall rates. That's another truther myth. The speed for the first four seconds of collapse of the towers can be determined by measuring the top block position. It's not free-fall rate but closer to about 0.6 g to 0.7 g. Some of the videos taken from the ground show that 12 seconds had passed before the collapse front had reached the ground, not the 9 seconds for freefall rate.

As measured using the videos, the south tower fell slightly more quickly than the north because of its larger mass in the larger upper block. That's consistent with the physics of a gravity-driven collapse.

Blowing out the floors with explosives in sequence won't make the towers fall at free-fall rate. That's another truther myth. Momentum has to be transferred from the upper falling block to the stationary floors below to accelerate them as the collapse front traveled downward. That will slow the collapse from free-fall rates.

There was lateral ejection of debris, but if you do the math it was traveling laterally at about the speed of the collapse front or less. The towers were 1365 feet high, so there was time for the debris to reach a few hundred feet laterally even though it wasn't traveling quickly. The lateral speed was on the order of 35 mph. The collapse front was moving much faster than that through most of the collapse.

For ejected debris free-falling for 8 seconds from near the aircraft impact region, it can go laterally 8sec*51.3ft/sec = 410 feet and easily reach neighboring buildings.

The duration of freefall from 363 meters is sqrt(2*363/9.81) = 8.6 seconds.

All of the debris isn't going to go straight down. A pile of falling debris a few stories high accumulated as the collapse proceeded. Some debris will inevitably get pushed outward. The perimeter panels broke easily at their bolted splices and were ejected laterally.

And no, the top block didn't disintengrate, at least not during the first 4 seconds. In general it stayed rigid for the first 4 seconds of collapse. The collapse front is seen moving downward along with the upper block. In some of the videos, it appears that the front didn't move downward as quickly as the top of the upper block. That's not unexpected, though. It takes a few stories of collapse for mass to build up at the front where it can propagate the collapse on its own without help from the upper block.

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The north tower tilted toward the south at the start of the collapse, the side that had a bowed-in wall. The sinking antenna and core is another myth. Initially people thought the collapse started with only the core sinking because the antenna appeared to drop as seen from the north side. If you look at videos from other vantage points, the antenna and upper section tilt toward the south as the collapse begins.

Some of the upper section appears to get crushed at the start of the collapse which is expected, but that doesn't deny the fact that the upper section tilted at the start of the collapse.

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Yeah, it's a "conspiracy myth," but the lies and disinformation of the yellow journalism which is the Hearst-owned Popular Mechanics is the biggest conspiracy theory of them all. You see, even if these towers didn't fall at freefall speeds (which they did), they still fell a hell of a lot faster than the 96 seconds it would have taken with your average so-called "pancake collapse."

To put it simple, the towers fell at a rate of speed that defies the laws of physics.

 

The towers didn't fall at freefall speeds. Measure it using the videos.

Those graphs about 96 seconds for collapse duration are based on an unrealistic assumption which was debunked long ago. 96 seconds would occur if after each impact the upper section came to a complete stop and then started up again. That doesn't occur because the floor that is impacted can't absorb enough energy to bring the falling section to a stop. The columns and other materials can absorb only a small fraction of the energy of the falling mass. Reseachers such as Bazant, Verdure, Kausel, Ulm, and Greening have done a reasonable energy analysis. Their models predict the observed collapse rates well.

Here's a pictorial of the layout of WTC7. The gash that occurred on the south side of WTC7 is in the same place as all the diesel risers. The gash happened in the worst possible place. That's one explanation for how the diesel leaks and fires occurred.



Composite photo of the gash:



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It was the SOUTH tower that tilted, then it mysterously disintegrated (exploding) in mid air before even reaching the ground, while the bottom of half collapsed straight down.

 

WTC7 fell at near free-fall rate because the collapse started near the ground and the mass of the entire building was falling from the start. Unlike the towers, there was no slowing due to momentum transfer because WTC7 collapsed from the bottom to the top. The stories above didn't have to accelerate the next stationary impacted floor below the collapse front.

WTC7 did fall slightly slower than freefall. That was due to the energy needed to crush the next floor above. There wasn't any concrete reinforcement along with the steel columns in WTC7 so there wasn't much material to absorb energy and slow the collapse. If there had been concrete with the coluimns, it would have collapsed at a slightly slower rate.

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I am not going to even debate with you about WTC-7 because it's pretty much a proven fact the building was demolished. We have emergency workers who were on the scene who said it was demolished, who heard the 20 second countdown, and we now have the early BBC press release which blows the cover off this completely. There's no need to make it any more confusing than it is.

 

WTC7 was already a total loss even before the collapse, so conspiracy claims about WTC7 are moot. It would have been demolished if the fires hadn't already caused it to collapse. There was a small chance of saving it just after the collapse of WTC1. The fire and smoke damage that occurred after that would have made it too expensive to repair.

The whole complex and six buildings were already wrecked. It's not as if WTC7 would need to be demolished 8 hours later as part of some conspiracy to get public support to invade Iraq.

The Banker's Trust building had its facade torn by debris impacts similar to WTC7 and is currently being demolished. It isn't worth the cost of trying to clean up the contaminants and do all of the repairs. Banker's Trust didn't have a diesel system like WTC7 which kept fires burning near the ground level all day. It also wasn't suspended over a substation like WTC7. It didn't have a long span bay area like WTC7 had on its east side. There was also a priority to clean up WTC7 because the substation was needed back on line as soon as possible.

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Where was it debunked, and by whom?

You make up lies with nonsense about each section coming to a complete stop, but where does it say this? What are you even talking about?

 

The graph you posted says it. You need to understand the graphs you post.

In that graph (by truther Judy Wood) the collapse has to stop after each impact and start up again. That's where the 96 second collapse duration comes from.

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Time to free-fall through one story height h=3.78 m starting from zero speed:

t = sqrt (2*h/g) = sqrt (2*3.78 m / 9.81 m/s^2) = 0.878 s

For 110 stories and each fall starting from zero speed:

t total = 110*0.878 s = 96 seconds.

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How do you know it was a total loss when all visible damage appeared to be minimal with only a few small fires on the lower floors? In a way it sounds like you're saying the building was damaged so bad they decided to bring it down. Is that what you're saying?

WTC was demolished because of what it housed. Not to invade Iraq. Again, you show how manipulative and disingenuous you are. You know it, too. Most of the public doesn't even know about Building 7, so stop trying to twist things.

It's currently being demolished? Where did you read this? Also, how does this apply to building 7 and what exactly are you getting at? Again, it sounds like in an offhand way you're admitting that WTC-7 was demolished because it was damaged.