Structural Engineer Kamal Obeid compares WTC 7 to a beer can

[newton3376]

In this presentation on May 8th Structural Engineer Kamal Obeid compared WTC7 to a beer can (the comment is about 53 minutes into the video).

He said something similar to: "WTC7 is like a big huge beer can with perforations in it so it performs like a beer can in a way when it is failing".

Can someone decipher this for me? I'm not getting the comparison he is trying to make here....is he saying the building should crumble and fall like a beer can?

Or is he saying something else? I'm a bit confused by the "beer can" analogy...

 

[triforcharity]

In this presentation on May 8th Structural Engineer Kamal Obeid compared WTC7 to a beer can (the comment is about 53 minutes into the video).

He said something similar to: "WTC7 is like a big huge beer can with perforations in it so it performs like a beer can in a way when it is failing".

Can someone decipher this for me? I'm not getting the comparison he is trying to make here....is he saying the building should crumble and fall like a beer can?

Or is he saying something else? I'm a bit confused by the "beer can" analogy...

I think the guy tried too many of his own experiments, and drank the beer first to get the empty cans.....

 

[Sam.I.Am]

Well then. If we're going to compare adult beverage containers to buildings then I'd like to know why engineers don't build buildings out of Jack Daniels bottles. I can stand on one and it won't break. That's got to be much stronger than a beer can. I mean I weigh at least 200 lbs (I sound fat don't I?), and an empty bottle can't weigh more than a pound at best so that's a 200 to 1 ratio. Right? Just slap a coat of paint on it where you don't want people to see in...

 

[fourtoe]

I am aware of the beer can experiment but it has more to do with neutral stress and geology:

Jim Fetzer made a better analogy to beer cans when talking about the crushed cars at WTC, "Those cars were crushed like beer cans after a frat party!" or something similar.

 

[fezzic]

I think Mr. Obeid was basically saying that the external framing of 7 WTC was analogous to a beer can.

I don't know if he was using that analogy with the idea that if you put a beer can or soda can on a flat surface and then evenly load the top, by say carefully stepping on the top of the can, often the can will be able to support a very heavy load. Then if you tap or dimple the sides of the can, it will fail catastrophically, often straight down, pancaking to a fraction of its normal height. I don't know if that is what he meant or not.

I poked around to get to that statement in the video and I didn't wait to listen to the rest of his talk.

 

[Oystein]

...
I don't know if he was using that analogy with the idea that if you put a beer can or soda can on a flat surface and then evenly load the top, by say carefully stepping on the top of the can, often the can will be able to support a very heavy load. Then if you tap or dimple the sides of the can, it will fail catastrophically, often straight down, pancaking to a fraction of its normal height. I don't know if that is what he meant or not.
...

Possible! We did that as kids. Often you did not even need to poke or dimple the can while you stand on it. The slightest touch with your fingertip sufficed as collapse initiation event. I guess the support structure was strained to the max, loads fully distributed, and any local variation would lead to buckling and rapid collapse progression, as further load distribution will bring every other support element to instant overload. And so you went straight down at pretty much free fall speed.

I think today's cans are made of thinner material than they used to (and with Europe's recycling laws and Germany's insistence on bottled beer, if you can't have it from a keg, I have not held a beverage can in my hand for years now), so not sure if you still can play the game and not crush the can before you have balanced your entire static load on it.

 

[njslim]

Toga! Toga! Toga!

 

[moorea34]

It's an excelent comparison. I use it also when I want to explain the WTC7 collapse to my students.

When the beer (or cola) can is full, it can sustain a great load...

But when it's empty, if you put all your weight on it and you create a little perturbation lateraly (even a very very weak chock), it "collapses"... quasi symetrically...

It's an instability, called "local buckling", that appears for thin structure compressed.
http://www.ansys.com/solutions/solid-mechanics-technology.asp


For WTC7, the material is not continuous, like beer cans, but the idea is the same since we have internal collapse before the frontage collapse. For the columns, it's a "simple" buckling due a hight slenderness ratio : http://www.uoregon.edu/~struct/courseware/461/461_lectures/461_lecture30/461_lecture30.html

 

[Telltale Tom]

Kamal is one of only 40 structural engineers who support ae911truth.

As he says in the video his focus is on WTC7. You see it is much more difficult for structural engineers to see anything wrong with the collapse of WTC1 and 2.

The beer can analogy is a bit odd if you can find a can with a core and columns in it then it might work for you.

I think he is misled when he says that main girders will deflect in fire and not push against the column. They will do both. As they deflect they push against the column and indeed the deflection can amplify the thrust of the bottom flange against the column.

However he is correct when he says that the collapse sequence video from NIST is not consistent with the actual failure. In the NIST model the internal structure fails and then the perimeter fails like a beer can from the top down. Whereas the floors maintained enough integrity to pull the wall down uniformly with the collapsing internal floors.

Not sure what NIST's explanation/excuse about this is as I have always thought that the WTC1 and 2 collapses were more important.

 

[Newtons Bit]

Kamal is one of only 40 structural engineers who support ae911truth.

And he's a complete 'ing loon who has no idea what he's talking about. A beer can is not a valid analogy for the collapse of WTC7. WTC7 collapsed due to the loss of lateral stability from the floors. You can't represent that with a beer can as it has no "floor" element.

 

[Telltale Tom]

K

However he is correct when he says that the collapse sequence video from NIST is not consistent with the actual failure. In the NIST model the internal structure fails and then the perimeter fails like a beer can from the top down. Whereas the floors maintained enough integrity to pull the wall down uniformly with the collapsing internal floors.

Not sure what NIST's explanation/excuse about this is as I have always thought that the WTC1 and 2 collapses were more important.

I have now done 1 hour research of extensive research to find out the discrepancy between the movie showing the NIST failure method and the actual failure method. If you look at NIST NCSTAR1-9A Figs 4.43 to 4.48. there is a scale, so that all the horizontal movements have been amplified so that you can see what happens. The scale says the movements are between -1m and 1m, thats +/-3.28ft. Although the images seem to appear that the horizontal movements are more like 30ft, they are not. Engineers do that type of scaling so that they can see what happens.... its really annoying to some architects and even some engineers who don't understand that type of thing.

I am sure that next time Kamal and Richard show the movie they will explain that the main reason it looks so different from the actual failure is the scale factor.

Any other ideas?

 

[sheeplesnshills]

Possible! We did that as kids. Often you did not even need to poke or dimple the can while you stand on it. The slightest touch with your fingertip sufficed as collapse initiation event. I guess the support structure was strained to the max, loads fully distributed, and any local variation would lead to buckling and rapid collapse progression, as further load distribution will bring every other support element to instant overload. And so you went straight down at pretty much free fall speed.

I think today's cans are made of thinner material than they used to (and with Europe's recycling laws and Germany's insistence on bottled beer, if you can't have it from a keg, I have not held a beverage can in my hand for years now), so not sure if you still can play the game and not crush the can before you have balanced your entire static load on it.

Yeah it still works fine with US soda cans. Its actually a great example of buckling reducing the strength of a can able to support a 200lb male (me) and instantly failing when tapped on the side. A beam when it buckles has very little strength compared to the original and I can see how a steel framed building could fall surprisingly fast once it has started moving down.

 

[sheeplesnshills]

And he's a complete 'ing loon who has no idea what he's talking about. A beer can is not a valid analogy for the collapse of WTC7. WTC7 collapsed due to the loss of lateral stability from the floors. You can't represent that with a beer can as it has no "floor" element.

A stack of cans would be closer

 

[DGM]

A stack of cans would be closer

I'll work on that tonight for you.

 

[Newtons Bit]

I'll work on that tonight for you.

As if you needed an excuse...

 

[alienentity]

I have now done 1 hour research of extensive research to find out the discrepancy between the movie showing the NIST failure method and the actual failure method. If you look at NIST NCSTAR1-9A Figs 4.43 to 4.48. there is a scale, so that all the horizontal movements have been amplified so that you can see what happens. The scale says the movements are between -1m and 1m, thats +/-3.28ft. Although the images seem to appear that the horizontal movements are more like 30ft, they are not. Engineers do that type of scaling so that they can see what happens.... its really annoying to some architects and even some engineers who don't understand that type of thing.

I am sure that next time Kamal and Richard show the movie they will explain that the main reason it looks so different from the actual failure is the scale factor.

Any other ideas?

I believe Mackey made the same observation a while back.

DGM - I was joking about the stronger center column in the achimspok thread. Just amplifying the red herring of the OP.

 

[newton3376]

And he's a complete 'ing loon who has no idea what he's talking about.

I assumed this was the case....

 

[R.Mackey]

I believe Mackey made the same observation a while back.

I did, as others had, but it turns out it's wrong. The NIST simulation actually does indicate much more displacement. Their color scale, however, maxes out at +/- 1 m displacement. This much displacement basically means "total failure" so they don't bother creating new colors for parts that have displaced even more.

The scale is intended to illustrate the lesser displacements, the ones that actually tell you what's going on with the structure's integrity, rather than try to detail the kinetic behavior of parts that are basically failed and flying around loose.

Thread is here.

And, in case it needed to be said, Kamal is a fool.

 

[Telltale Tom]

Ah so I guess it needs more than an hour of research.

So I guess that NIST's LS-DYNA model underestimates the strength of the connections to the perimeter frame, as the internal floors fail before the outer shell. So it does not represent the actual failure mechanism of WTC7 and what was the point of putting it in the WTC report?

Is this grounds for a new investigation?

 

[dafydd]

I have now done 1 hour research of extensive research to find out the discrepancy between the movie showing the NIST failure method and the actual failure method. If you look at NIST NCSTAR1-9A Figs 4.43 to 4.48. there is a scale, so that all the horizontal movements have been amplified so that you can see what happens. The scale says the movements are between -1m and 1m, thats +/-3.28ft. Although the images seem to appear that the horizontal movements are more like 30ft, they are not. Engineers do that type of scaling so that they can see what happens.... its really annoying to some architects and even some engineers who don't understand that type of thing.

I am sure that next time Kamal and Richard show the movie they will explain that the main reason it looks so different from the actual failure is the scale factor.

Any other ideas?

Ooooh,a whole hour!