New pedestrian bridge collapses in Miami...

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For that kind of construction approach to work it seems to me that the span has to be engineered and built to withstand both it's own weight (dead weight) unsupported, and also the live weight of the construction workers and materials needed to erect the mast and connect the cables. I'm betting that the span was under-engineered for the unsupported construction live weight, or not built to spec (poor materials or method).
 

strangenh

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Isn't part of engineering knowing that your over-complicated product is going to be used by idiots?
Sure, but there's idiots and then there's idiots. Materials screwups, implementation screwups, inspection screwups, the potential for failure is greater than can be planned for unless we're winding up with 50X overengineered 50X $ projects.
 

strangenh

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Everyone interested in how crap like this happens should go out and get a copy of Petroski's To Engineer Is Human: The Role of Failure in Successful Design to get an idea of how civil engineering approaches failure, learns from failure, and engineers to avoid failure. There's no perfection on this mortal coil.
 

TLB

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Kevin_NH

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Here's the official story on the "missing" tower and cables at FIU:
USAToday said:
The central column and cables that appeared in the design of a collapsed pedestrian bridge in Miami were decorative and not needed to support the span, federal investigators and bridge designers said Friday.

Bridge engineers had questioned why the column designed to rise above the bridge deck to a height of 109 feet wasn’t erected before a large section of the bridge deck was hoisted into place Saturday.

...the column...was not needed for a truss bridge.

Cheryl Stopnick, an outside spokeswoman for FIGG Bridge Engineers, which designed the bridge, said the structure was “truss bridge with above-deck truss elements.”

...the cables designed to fan out from the column weren’t needed to support the bridge deck, he said.

“As I understand it, these were cosmetic,” Accetta said. “They were not structural members.
Both FIGG and MCM have had issues with their bridges collapsing on past projects.
 

silversquirrel

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Actually it's a code word for useless eaters of all forms.

When things are "simple" - it's pretty easy to figure out who isn't pulling their weight by doing actual useful work. As things get more complex - it gets easier and easier for people to become leeches on the system thru all sorts of obfuscation and deceit. Everything is so damn complicated - that nobody can figure out what the hell is really going on. This effect permeates thru the society on a personal , familial, community - and governmental level.

Since - no matter what anybody tries to tell you - actual work is still required to keep society running - and the people who do actual work figure out they're being used as pack mules sooner or later , what you get is a critical mass of leeches that sooner or later collapse the society.

This is the basic idea behind Ayn Rand's "Atlas Shrugged".

It's actually been happening for a while now. For at least the last ten years I've been seeing numerous instances of people making comments on the internet and in my personal life that basically amount to " f*** this shit - I'm out of here" . These were productive people who just said screw it and gave it all up to go live in a cabin in the woods or sit on a beach somewhere.

In the past I've said it myself when people tried to use that whole "Fellow Americans" thing on me. Screw my "fellow Americans". They've been screwing me for decades. I don't feel guilty at all about returning the favor.
Or the other Ayn Rand book, Fountainhead.
Architect creates something his way on the condition it be built exactly the way he intended. Random parisite hijacks or otherwise bastardizes the project. Architect takes it personally, and literally blows up the construction site.

Ok, so one my of favorite old movies, with Gary Cooper as the Architect. Not really anything to do with the bridge in miami.
 

vicorjh

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“As I understand it, these were cosmetic,” Accetta said. “They were not structural members.

For cosmetic purposes, we tension, tune, and test all artistic features.
 

enbloc

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I wonder how many pedestrians were killed crossing at the light before the bridge collapse...
 

Kevin_NH

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I wonder how many pedestrians were killed crossing at the light before the bridge collapse...
About one a year.

Cheryl Stopnick, an outside spokeswoman for FIGG Bridge Engineers, which designed the bridge, said the structure was “truss bridge with above-deck truss elements.” ...the cables designed to fan out from the column weren’t needed to support the bridge deck, he said.
. . .
As I understand it, these were cosmetic,” Accetta said. “They were not structural members.
For cosmetic purposes, we tension, tune, and test all artistic features.
How do you tension, tune, and test the cables and column, when those components weren't built yet?

They were tensioning the internal ties of the truss bridge with above-deck truss elements, not the column and "suspension" cables that didn't yet exist.

Here's our favorite Canadian YouTuber with his description of a "truss bridge" and a theory for the failure during de/re-tensioning:
 
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Salyeica

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Better to have fallen now than with 10 vehicles underneath and 40 pedestrians crossing the span, I suppose...
 

Boris

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I remember that as "Build something even a moron can use and only a moron will use it"
that bridge was probably up to task but but I think that they misquoted it and let morons design it or build it or install it, may be all of those.

Engineering math is hard and racist, all formulas are made by white men. We need engineering so all folks can have good jobs designing bridges and use all those formulas invented by un-white lesbians to defy patriarchy.
 

calsdad

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i don't do twitter but this lady was linked in an article....she seems to be there shooting cell phone vids around the clock.
Monique O. Madan (@MoniqueOMadan) | Twitter
Wow. That woman has some crazy eyes shit going on.

and meanwhile in other related LOL news ............ in the " that didn't take long " Department: ( this goes out to the " we need to have building codes because we can't have the libertarians running things!!! " crowd....) :

State played key role on FIU bridge, despite efforts to distance itself after collapse

State played key role on FIU bridge, despite efforts to distance itself after collapse


TALLAHASSEE
In the hours after the collapse of the Florida International University pedestrian bridge that killed six on Thursday, the Florida Department of Transportation
quickly attempted to publicly distance itself from liability, calling its role “limited.”
 
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calsdad

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If you design something to be "idiot proof" they'll then design bigger idiots to negate your new design.
You're correct - to a point.

But at least some of the reason why the Germans lost WW2 - is that their engineers complicated the living shit out of everything they designed. They therefore made their weapons harder to produce , easier for the slave labor workers to sabotage by not making stuff correctly in the first place - and then harder to fix in the field. When you're a Wehrmacht soldier whose under attack by hordes of Soviets - you don't want to have to pull out some stupid technical manual to fix your broken tank. You want to pull out a sledgehammer and bash something back into place to make it work - and then keep going. Under the "understanding" of the engineers who design things - a lot of the time the "users" are idiots who don't comprehend their wonderful creation. But when your product fails out in the field - because somebody didn't follow your long detailed laundry list of instructions on EXACTLY how to use what you designed - who is really the idiot? The person who didn't follow your instructions to the letter - or the engineer who was living in la-la land and didn't understand how his wonderful design was REALLY going to get used out in the field?

You can't design to accomodate every single idiot in the world - because people are correct: they will just invent a bigger idiot. At a certain point idiots have to be held liable for their idiocy. But there is also such a thing as dealing with the real world and not overcomplicating the shit out of everything when complication serves no purpose.
 

headednorth

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Me thinks this bridge collapse is a metaphor for and foreshadowing of society in this country. Shortcuts were taken. The job was done poorly. Safety was not a primary objective. A company was hired that has had multiple collapses in recent history. And no one is taking responsibility for the mess, leaving tax payers on the hook for the cost.

Society will collapse under its own weight, just like this bridge.

Yeah, we're f*cked in this country.
This was a theme in Atlas Shrugged.
 

richc

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There's a waitress in a local pub with those eyes. I always figured she was nuts.

One night we went with my son and his buddy for dinner. My son's buddy sees her and freezes. Calls her a level 5 stalker. He dated her once and was not interested. Said she was relentless, and frightening, in her pursuit of him.

Kid was truly scared. Eyes are a window into the soul...

:)


Wow. That woman has some crazy eyes shit going on.
 
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If you watch the dash cam in slow mo you can see the bridge fails exactly where they are adjusting the tension on the steel reinforcement. Then most of the destruction you see is a result of the bridge falling and hitting the ground. What is actually amazing is a portion of the bridge on the right, a couple trusses, actually survive the impact. That shows the design is quite resilient.

The youtube video analysis is interesting. There could certainly be something to the theory that the end that ultimately failed was installed flexing down, because that end of the bridge was lifted further in from the end. Then once in place, they might have tried to invert that flex, and arc that bridge section slightly up. I wonder if they were using the crane to pull that point up as they adjusted the reinforcement and they just stressed the structure too much.

Hindsight is 20/20 but such an adjustment or lift should not have been done with people under the bridge but rather with the lift structure still under it. But of course they had that big celebration planned for reopening the road--can't be the guy that cancels that! Just like no one wanted to scrub the Challenger Space Shuttle launch.

Just my speculation--I look forward to reading the NTSB analysis.

Also, you can always spot the photo-op people on a job site--they're the ones with the vis vests with the creases, un-scuffed hard hats. Those folks were noticeably absent when the one worker was cranking on the part that failed.
 
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