29 Structural & Civil Engineers Cite Evidence for Controlled Explosive Demolition

[Toke]

I like the yardstick and coin video.
Very educational.

 

[Christopher7]

No, I keep telling you that I agree that they both find that there is a phase of acceleration indistinguishable from freefall. The devil is in the details, namely in the accuracy of this measurement. You don't seem to want to understand that this is not an accurate measurement, meaning that we cannot confidently say that there was no energy to bend columns.

What exactly is not accurate? The time? The distance?

No, sorry, you're simply wrong. A horizontal line in a velocity graph indicates a constant velocity (i.e. no acceleration, i.e. maintaining its current velocity), not a constant position, unless it is a horizontal line on the level of zero velocity, which it isn't.

You may be right. I'll check with someone I trust and get back to you.

 

[tfk]

The graphs clearly show a momentary pause. When the line is flat [horizontal] between two or more spots, that wall is NOT moving downward.
http://img34.imageshack.us/img34/5822/graphcompare.jpg

OPEN YOUR EARS. More important, OPEN YOUR BRAIN.

When the line is horizontal on a HEIGHT vs time graph, then the wall is not moving.

When the line is horizontal on a VELOCITY vs. time graph, then the wall IS moving (as long as it is horizontal at a value other than zero).

Is this a HEIGHT vs. time graph, Chris? Or is it a VELOCITY vs. time graph?

You have now been told this exact mistake explicitly about 10x now.

Chris, I am gonna stop beating you about the head & shoulders. You're punch drunk & don't know how bad you're being trounced.

If one of your more knowledgeable twoofer friends had a lick of compassion, they would have thrown in the towel for you, taken you aside and explained things to you. Apparently, they are not that compassionate.

Tom

 

[tfk]

I like the yardstick and coin video.
Very educational.

Yeah, cool no?!

Now, use it to postulate a way (highly unlikely, but possible) that the wall could have come down faster than a free falling object...

tom

 

[Caustic Logic]

How do I know it's bunk? It starts with "X-number of total experts say..." It doesn't work all the time, but usually with twoofers it's a handy shortcut. Try it next time.

 

[H'ethetheth]

A progressive collapse, spreading accross the core would result in the screenwall and west penthouse collapsing in a similar manner. According to NIST, it took 1 to 2 seconds for the collapse of each north south column row to cause the collapse of the next row. There were 6 column rows in the core area under the screenwall and west penthouse.

Horizontal collapse time line:
Time line using data from NCSTAR 1-9 Vol.2 pages 579-585 [pdf 241-247]
-1.3s Column 79 failed [Group 1]

...

6.3s Columns 61, 64 and 67 failed [Group 6]

BTW: There is no explanation for column 66 [Group 8] failing when it did. The debris damage occurred 7 hours earlier and the fires had burned out in that area long before 5:20 PM.

Furthermore, Group 7 was supported in the north south direction by the columns in Groups 6 and 8. It could not fail before Group 8 as the result of "loss of lateral support in the north south direction" as NIST states on pg 612.
1-9 Vol.2 pg 612 [pdf 274]
13. Horizontal Progression of Failure.
"The middle line of interior columns directly behind the initially severed exterior columns buckled before the two north-south lines of columns immediately to their east. The middle line of interior columns [Group 7] lost lateral support in the north-south direction over 11 floors in response to the structural damage that was imposed."

So you're now all the way down to: "There is no explanation for column 66 [Group 8] failing when it did"?
We're talking about a simulation here. A qualitative simulation at that. NIST wants to know what sort of thing most probably went wrong so they can prevent it from happening in the future. They don't need to know if the descent was at 97% of g or at 99.7%. It was as good as unimpeded. That will do. That will give insight into what kinds of things went wrong. Comparing it to the observations (and I have to say, the comparison is absolutely amazing in my opinion) only serves the purpose of showing them they got the general collapse causes right. The causes that they can do something about in the next generation of buildings.

NIST has little hard data on when things happened in the real building and damage estimates were based on photographic evidence from hundreds of metres away. There are bound to be differences, and nobody will ever know exactly where they are or why they occurred, because no one will ever know precisely what condition the building was in when it started to fall. But to NIST, this is of limited concern. They want to make better buildings.

 

[alexi_drago]

You may be right. I'll check with someone I trust and get back to you.

When can something with a non-zero velocity be stationary?

 

[Newtons Bit]

When can something with a non-zero velocity be stationary?

When someone does't know wtf they're talking about.

 

[Christopher7]

So you're now all the way down to: "There is no explanation for column 66 [Group 8] failing when it did"?
We're talking about a simulation here. A qualitative simulation at that. NIST wants to know what sort of thing most probably went wrong so they can prevent it from happening in the future. They don't need to know if the descent was at 97% of g or at 99.7%. It was as good as unimpeded. That will do. That will give insight into what kinds of things went wrong. Comparing it to the observations (and I have to say, the comparison is absolutely amazing in my opinion) only serves the purpose of showing them they got the general collapse causes right. The causes that they can do something about in the next generation of buildings.

NIST has little hard data on when things happened in the real building and damage estimates were based on photographic evidence from hundreds of metres away. There are bound to be differences, and nobody will ever know exactly where they are or why they occurred, because no one will ever know precisely what condition the building was in when it started to fall. But to NIST, this is of limited concern. They want to make better buildings.

Yada yada.

They have columns failing for no apparent reason. That is not science, it's lying!

You did not address the FACT that Group 7 could not fail before Group 8.

That is a blatant lie!

 

[H'ethetheth]

What exactly is not accurate? The time? The distance?

Okay, here we go:

1. He clicks on a pixel that contains the corner of the building. How big is the pixel relative to the distance traveled at that time and the distance traveled per frame?

2. He calibrates the distances by measuring a more or less known distance on the building. IIRC from the 29th floor to the top. How many pixels per floor? What is the baseline for the height number from the NIST report? The floor or the window line? How much distance is between them? And how big are these errors compared to the total calibration height of about 240 ft?

3. What is the distance of the camera to the building? It's far away, but there will be some foreshortening in the picture. It is unknown how much.

4. How many movie frames are there? The approximation of a curve becomes less accurate with fewer points.

5. What is the spread of the points around the actual trajectory? If the positions determined are jittery, differentiating this will make the velocity profile more jittery relative to the magnitude of the velocity, making curve fitting more error prone.

That's all off the top of my head.

You may be right. I'll check with someone I trust and get back to you.

Good luck.

 

[rwguinn]

When can something with a non-zero velocity be stationary?

When the reference frame is moving with the same velocity?
[disclaimer](Valid only when V<<C)[/disclaimer]

 

[Toke]

Yeah, cool no?!

Now, use it to postulate a way (highly unlikely, but possible) that the wall could have come down faster than a free falling object...

tom

No problem, it could have been connected to some floor/horisontal bracing connected further inside the building. If the center of gravity droped at 1G you could get a lever effect pulling down on on the wall adding to its own 1G acceleration.
It is not likely, and would not have much effect.


Personally I don´t belive you can get very accurate measuments from a video not set up for the purpose with the correct equipment. (high speed camera, dots on building?)

 

[H'ethetheth]

Yada yada.

I imagine your fingers are in your ears (or eyes) when you do that?

They have columns failing for no apparent reason. That is not science, it's lying!

I didn't read a percent of the report so far, but I would be satisfied with the explanation that they buckled for unclear reasons, or simply overloading due to load redistribution.
I suspect however that if you ask this question to someone who ran the simulation, they will be able to tell you.

ETA: It would probably suffice to ask an engineer who has read the entire report.

You did not address the FACT that Group 7 could not fail before Group 8.

That is a blatant lie!

1. It could and did in the simulation.
2. No explosives were included in the simulation
3. No one will ever know if it did in reality
4. Whether it did is not important to the outcomes for the new buidling codes

In other words, you have nothing.

 

[tfk]

You may be right. I'll check with someone I trust and get back to you.

"You'll check with someone ..."

Chris, this is the equivalent of 2 + 3 = 5.

And you're going to go "check with someone you trust"...?!!

You should have acknowledged about 200 posts ago that you had no *#&#ing idea what people were talking about. Your obnoxious PRETENSE that you followed the conversation wasted several hours of my time.

Jerk.

tom

 

[H'ethetheth]

"You'll check with someone ..."

Chris, this is the equivalent of 2 + 3 = 5.

And you're going to go "check with someone you trust"...?!!

You should have acknowledged about 200 posts ago that you had no *#&#ing idea what people were talking about. Your obnoxious PRETENSE that you followed the conversation wasted several hours of my time.

Jerk.

tom

Good point. I'm now wondering if he understands the specific meaning of a lot of the words I've used.

Differentiate
Derivative
Trajectory
Simulation
Model
Normal

By God...

 

[tfk]

Yada yada.

They have columns failing for no apparent reason. That is not science, it's lying!

You did not address the FACT that Group 7 could not fail before Group 8.

That is a blatant lie!

Mind boggling, Chris.

You are STILL making stupid, baseless assertions on topics that are as impenetrable to you as quantum physics.

With "I'll check with someone as to whether 2 + 3 = 5", you LOST the right to assert ANYTHING, or to pass judgment on ANYONE.

You don't get to do anything except ASK "what do you engineers think about that?"

That is, unless you've got on MONSTER of a masochistic streak.

tom

PS. Chris, these guys have PhDs in Structural Engineering. Now, tell me again about how they "have columns failing for no apparent reason".

How about "they have columns failing for no apparent reason for reasons that you, Chris, don't understand".

That's be accurate. And, at this point, a lot less embarrassing for you.

 

[Christopher7]

Okay, here we go:

1. He clicks on a pixel that contains the corner of the building. How big is the pixel relative to the distance traveled at that time and the distance traveled per frame?

2. He calibrates the distances by measuring a more or less known distance on the building. IIRC from the 29th floor to the top. How many pixels per floor? What is the baseline for the height number from the NIST report? The floor or the window line? How much distance is between them? And how big are these errors compared to the total calibration height of about 240 ft?

3. What is the distance of the camera to the building? It's far away, but there will be some foreshortening in the picture. It is unknown how much.

4. How many movie frames are there? The approximation of a curve becomes less accurate with fewer points.

5. What is the spread of the points around the actual trajectory? If the positions determined are jittery, differentiating this will make the velocity profile more jittery relative to the magnitude of the velocity, making curve fitting more error prone.

That's all off the top of my head.

Pure denial.
If God said WTC 7 fell at free fall acceleration you would dispute it.

There are enough points to confirm beyond all doubt that WTC 7 fell at free fall acceleration.

If the measurements were not accurate NIST would not have stated unequivocally that WTC 7 fell at free fall acceleration.

The measurements are accurate and you are talking thru your hat.

 

[Christopher7]

Mind boggling, Chris.

You are STILL making stupid, baseless assertions on topics that are as impenetrable to you as quantum physics.

Hogwash! Dispute with facts instead of hand waving with insults.

PS. Chris, these guys have PhDs in Structural Engineering. Now, tell me again about how they "have columns failing for no apparent reason".

They are lying. Group 7 cannot fail before Group 8 because the girders between them were providing north south lateral support to the columns in Group 7.

Loose the personal attack and deal with the facts.

 

[jhunter1163]

If God said WTC 7 fell at free fall acceleration you would dispute it.

Yes, because God doesn't exist.

Hey, someone had to say it.

 

[tfk]

Toke,

No problem, it could have been connected to some floor/horisontal bracing connected further inside the building. If the center of gravity droped at 1G you could get a lever effect pulling down on on the wall adding to its own 1G acceleration.
It is not likely, and would not have much effect.

Not bad...

... for a Socialist.

Personally I don´t belive you can get very accurate measuments from a video not set up for the purpose with the correct equipment. (high speed camera, dots on building?)

Guys that are experienced with video really can do remarkable things. It takes an artisan, not just an engineer.

But an artisan in tech issues is simply someone with a lot of experience who takes a lot of pride in the quality of his/her work. Guys that are that good can get sub-pixel resolution. But we don't need that here. We just need to not make the mistake that Chandler made.

Tom

PS. Of course, if a superb artisan used any of these techniques, ignorant twoofers would say that they were "fudging their data to get the answer that the NWO wanted"...??!!