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WTC Collapse and My Shower Brush

SanderO

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This morning I got an lesson on the mysteries of the twin tower collapses.

I was taking my morning shower. I have a long handled shower brush, actually two, one the long hand broke and so I can't hang it by the little loop and can't reach as far either. But the bristles are still good so continue to use it. It's place it on the ledge/top of the tun which is also use as a shower. Sometimes I use this one and others times not. It's older and the bristles are softer so it's better for scrubbing my face for example.

So I pick up the brush and wet it and then get some soap on it to lather up for scrubbing and do the scrubbing and rinse it under the shower and place it back on the tub ledge and resume with the long handled brush for my back. Lo and behold the brush slips from the tub edge after 15 or 20 seconds and ends up in the tub. How did this happen?

Perhaps some water from the shower head came down upon it exerting just enough force to somehow move it laterally and dislodge it. Possible but I don't think so.

I began to imagine that the forces holding the brush perched on the ledge were not enough to move it in any way. It was just like the glass perched on the edge of my desk. One could say in balance. So if it was perhaps just a single drop which changed everything and caused the brush to slip over the edge. Well for starters the brush was wet, perhaps a bit soapy and slippery and this would lesson the force needed to displace it. But the point is that the static condition was clearly very close to changing and then gravity would rule. The top surface of the tub was also rounded and probably a bit wet and likewise not the best surface to balance or support anything. But this clearly was a situation which WAS stable, looked stable and IS stable all the time... the brush lives in this spot until I use it for showering and then replace it. So wet created a very close to failure condition where perhaps... gravity was able to exert enough force in perhaps the right place to just tip it over to unsupportable and it slipped into the tub.

As I picked it up and placed in back in its home, I realized how much this was like the tops of the twin towers which just before they plunged were teetering just above the stable state and it wouldn't take much to change that into a top dropping. I suppose if I had very detailed video of the brush I would be able to see slight movement before release... the forces at work inside the brush. But I was showering and only had my imagination.

With the towers there was no visible BIG event that preceded the top drops. It was standing tall one sec and then it was descending and then soon after it was gone. Failures are often like that... stable until they are not.
 

Kat Dorman

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I'm surprised the usual suspects have not piled on the ridicule already. Give it time.

Your anecdote has a lot more relevance to the subject of progressive collapse than 99% of the chatter about CD. It goes to the nature of metastable systems and systems which are subject to cascading dynamics, specifically cascading failure. It's funny that I've had soap do the same thing and it sparked some of the same thoughts.

Okay, I'll relate one of my own. I once took a glass baking dish from the dishwasher and set it into the cupboard, not gingerly but certainly gently. Within moments, it explosively shattered into hundreds of small shards scattered all around the kitchen. It's reasonable to assume that it was manufactured with a defect (not apparent to the eye) which imposed large internal stresses. That dish had been around for years, been in the oven/fridge/dishwasher countless times. The internal stresses did not cause spontaneous disintegration during this time. Perhaps it was "wound tight" from the factory, but it was stable - even against significant perturbation - in any sense of the word.

It had already cooled while sitting in the dishwasher. It was probably the mild vibration of setting it down which pushed it over the edge, but even then it didn't shatter immediately. My hand was out of the cupboard when it went. If I'd set it down gingerly, maybe it would have taken several hours to shatter, while I was sleeping. I could've opened the cupboard in the morning to find little pieces of glass strewn and wonder WTF...

Likewise, the enormous gravitational energy of a skyscraper exceeds the energy necessary to disintegrate the structure, so it's also a metastable structure. This is by design. However, the strain potential barrier keeping it within the boundaries of stability is normally quite high, and live/dead/wind loading are far from compromising the stability. If the capacity reduces to the point of demand, however, the knife edge has been crossed. The big fallacy with Szamboti, Chandler, et al clowns, is claiming that the residual capacity of the intact lower section is 100% of design and is such to rapidly bring the upper section / debris back to stability - which is static equilibrium.

In fact, this is where the cascading failure part comes in. Almost every mechanical action serves to erode residual capacity, and almost nothing acts to increase it. The notable exception is the state of full compaction, where things are as squashed as they can get without taking the force up orders of magnitude (like turning carbon into diamond). Otherwise, 100% as built capacity only comes from following the print carefully! This is entropy at work in the large. No accidental configuration of mangled steel and fractured concrete is going to provide the same resistive force as a carefully designed architecture.

Processes in cascading failure are self-accelerating. Tilt causes eccentric loading, which diminishes capacity in itself. Increasing tilt angle also provides an ever-increasing lever arm, which in turn increases the torque and therefore angular acceleration and eccentricity. This is literally a snowballing process.
 

Thoreau72

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That mystery in your shower will no doubt keep you befuddled for days or weeks, eh Sander? :cool:
 

SanderO

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The nature of how a structure experiences a progressive failure is missing from virtually all WTC collapse discussions and debates.

This is it in a nutshell:

The big fallacy with Szamboti, Chandler, et al clowns, is claiming that the residual capacity of the intact lower section is 100% of design and is such to rapidly bring the upper section / debris back to stability - which is static equilibrium.

What we saw was the capacity was being eroded... the reserve strength was slowing consumed by heat.... distortion mechanical failure and so forth. As long as the service loads did not exceed the strength it appears normal. But when it goes... it goes big... and visible failure then rapidly propagate.
 

MaggieD

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I'm surprised the usual suspects have not piled on the ridicule already. Give it time.
I wondered throughout the whole OP: "Who gets dirty enough that they have to use a brush to get clean in the shower?"
 

Thoreau72

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SanderO

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I wondered throughout the whole OP: "Who gets dirty enough that they have to use a brush to get clean in the shower?"
dunno... they sell them so someone must see their purpose... they do stimulate the skin like a loofa and defoliate.
 

the_recruit

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I wondered throughout the whole OP: "Who gets dirty enough that they have to use a brush to get clean in the shower?"

Oh his FACE no less. Who is he? Paul Bunyan? Maybe Sasha Grey? :mrgreen:
 

SanderO

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So many idiots and so little time....
 

the_recruit

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So many idiots and so little time....
Sorry, sorry. Didn't mean to interrupt. Please go on. I think you were saying something about your pet Babe the Blue Ox?
 

SanderO

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No... you misunderstood. But thanks for trying.
 

the_recruit

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Awww, man. Come on, don't be like that. Seriously, I like this thread. I mean that. Bathroom anecdotes and how they relate to the WTC collapse. Great topic! Really!
 

Kat Dorman

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Bathroom anecdotes and how they relate to the WTC collapse.
I do some of my best thinking when I'm taking a ****. How about you?

PS - any comments on metastability and its relation to progressive collapse of large buildings? Want to see some fiber bundle models of collapse initiation?
 

Oozlefinch

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I'm surprised the usual suspects have not piled on the ridicule already. Give it time.
It is just that most of us in here have the ability to use cognitive reasoning, and thus can recognize satire and/or sarcasm.

We do not take anything we read as gospel truth.
 

SanderO

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It is just that most of us in here have the ability to use cognitive reasoning, and thus can recognize satire and/or sarcasm.

We do not take anything we read as gospel truth.
Well... the shower brush incident was real and it did get me thinking about how a system appears completely stable on instant and then unstable the next because it doesn't necessarily take much to tip it from stable.. appearing like the rock of Gibraltar to unstable appearing like a collapsing sky scraper.
 

SanderO

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I do some of my best thinking when I'm taking a ****. How about you?

PS - any comments on metastability and its relation to progressive collapse of large buildings? Want to see some fiber bundle models of collapse initiation?
It's called multi tasking... get out stuff...
 

Menard_K

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Well... the shower brush incident was real and it did get me thinking about how a system appears completely stable on instant and then unstable the next because it doesn't necessarily take much to tip it from stable.. appearing like the rock of Gibraltar to unstable appearing like a collapsing sky scraper.
Your brush was not part of a system that was designed to be stable, also, may I point out
that your brush moved sideways in order to fall, and so you get sideways motion, with very
little perceivable motivation for it. So my question here is WHY did all that rubble on top of
the WTC towers remain right on top, & not shift to one side or another?
 

the_recruit

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Your brush was not part of a system that was designed to be stable, also, may I point out
that your brush moved sideways in order to fall, and so you get sideways motion, with very
little perceivable motivation for it. So my question here is WHY did all that rubble on top of
the WTC towers remain right on top, & not shift to one side or another?
That's been explained time and time again. The structure wasn't capable of withstanding the shear stresses necessary to tip over like a rigid object.
 

the_recruit

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radioman

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Wow, those are some big words. I'm incredibly impressed. You must be wicked smart!
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I've been reading her posts for a few weeks.....she REALLY is wicked smart.

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Originally Posted by Kat Dorman .
. Want to see some fiber bundle models of collapse initiation?

------------
Well....this seems vaguely erotic....I think she likes you.
 

Menard_K

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That's been explained time and time again. The structure wasn't capable of withstanding the shear stresses necessary to tip over like a rigid object.
I never said anything about the whole tower tipping over, I said that there must be somekinda heavy magic involved here to keep the "piledriver" mass on top of the WTC structure rather than have it loose so much mass out the sides that the destruction would have to stop.
 

the_recruit

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I never said anything about the whole tower tipping over, I said that there must be somekinda heavy magic involved here to keep the "piledriver" mass on top of the WTC structure rather than have it loose so much mass out the sides that the destruction would have to stop.
Why would it lose so much mass out the sides? Gravity vector is down, not sideways.
 
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