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Alert

There will be more on the Florida bridge collapse.

Mar 16, 2018 12:14PM PDT
https://www.reuters.com/article/us-florida-bridge/bodies-cars-still-pinned-by-deadly-miami-bridge-collapse-idUSKCN1GS16M
During the live coverage of the rescue attempts, the newsreader was interviewing visibly upset FL Congressman. He repeated several times that the two companies that built and installed it had impeccable records and were experienced in this newer type of work. He repeated it so often, and in so many of the same words, that it's about all I remember of the coverage.
Not so, says almost every follow-up story.

Discussion is locked

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My #2 daughter is a reinforced concrete engineer
Mar 16, 2018 2:50PM PDT

She works for Maryland SHA. I sent her some articles on it. We discussed it. She said they used "self healing" concrete and while that is supposed to help close cracks, it also makes a weaker concrete, so has to be a bit thicker, or something to that effect.

Just looking at it, I could see a number of design flaws. It did have triangulation added between the top and bottom slabs, but looked to me it wouldn't protect strongly against sideways motions. It's also perfectly flat, whereas most walkovers have a slight arch to them, which directs force toward the foundation bulwarks at each end. It's almost 200' long too! I don't know any slab that without strong metal beams aiding it, would stretch that far on a flat slab and keep it from breaking other than ancient monolithic structures. It weighed almost 1000 tons! It's a walkover, not for heavy vehicles, and even counting for maybe many people being on it at the same time, I think a metal structure with a walk cover of 2-3" concrete, like sidewalks have, would be much better, and safer. There's one on the B&A bike/walking trail that crosses a major highway 100 here in Maryland, (main route from Annapolis to DC) built in that manner, and it's longer I think than the one that collapsed. It's been there for quite a number of years.

With snow on it.
http://saki.iwarp.com/images2016/bridgeOver100_160125.JPG

Here's google street view of it.

Here's another over highway 50 which runs from Annapolis to DC, it's 10 lanes with wider divider in middle than the collapsed one in Florida.

Uhh, did I already mention "arched"?

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Hi James...
Mar 16, 2018 2:56PM PDT

the millenium bridge in London suffered with swaying because of people walking over it. They had to fit dampers to cure it. It's like when soldiers march across bridges, can cause problems.
Dafydd.

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I remember in basic
Mar 16, 2018 3:28PM PDT

It was always "walk at ease" when using a crossover. I've heard of some wooden on steel football stands collapsing from synched stomping. That was always fun when in High School at a game, the sound effect really affected the other players. Maybe that's why it was still wooden although other schools had newer concrete ones. Just not the same effect stomping in synch on those. LOL, More fun was the song everyone sang as the band started playing, when your team won as the other left the field, just to rub it in fully, along with the wave.

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Look up Galloping Gertie, a famous US bridge.
Mar 16, 2018 4:06PM PDT

Should find a video of its collapse. Scary.
Attributed to resonance, from the wind. Much advance warning, which is how it got filmed.

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Good comment and links, James.
Mar 16, 2018 4:00PM PDT

I think this also will jog your memory: Those Gothic cathedrals stayed up, with "primitive" construction, because the roof loading was transferred outward by the design. Not enough? Add flying buttresses.
Even with only people loads an arch is necessary. Out here we see many big rigs - big - on the roads. A loaded flatbed is flat; unloaded, you could run a Soapbox Derby on it.
Again, what I remember is the Congressman's insistence on the quality of the constructors, which turns put to be a phantom.
Now, this has nothing to do with the man's party, which happened to be Republican: If federal money went into the bridge, I wonder if he was thinking of the part he might have played in it. Sad
In Navy boot camp it was different. The command was "Route step, march!" Seems silly, until you see one collapsed. More important to Army and Marines, because they often cross battle-weakened or makeshift bridges.
It came about, they say, because of a Coed's recent death attempting to cross the busy road. One dead before; several after. Sad

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Hey! Girls don't do construction!
Mar 16, 2018 4:02PM PDT
Happy
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Just thought I'd add a link...
Mar 16, 2018 4:05PM PDT
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'Inaugurated in May, closed in June'
Mar 16, 2018 4:17PM PDT

At least it did better than Henry VIII's Mary Rose, also in the news recently.
On my one trip to London, before 2000, I got to Waterloo Station and saw St Paul's in the distance. The 'St Peter's' of my former church.
Also a large bust of Nelson Mandela on the walkway.
And, I survived the Tube. That was about a year after the King's Cross St Pancras holocaust.

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Surviving the Tube.
Mar 16, 2018 4:25PM PDT

Yes Kings Cross was bad, but surviving the Tube these days is about getting on and off without bombs, nutters, and unpleasant characters without incident.
Dafydd.

Post was last edited on March 16, 2018 4:26 PM PDT

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The escalators are the steepest I've seen,
Mar 17, 2018 7:12PM PDT

packed with commuters, all of whom walk [run?] vice standing. I had to move also, with luggage. I was afraid I might lose my footing, in which case I would carry everyone below me. International incident.
Steepness was a part of St Pancras. The fire burned unnoticed upward, in the grease and dirt underneath the ramp assembly, until it reached the top. When the doors next opened it burst out like a flamethrower on top of the walk. Like opening a door on any fire, but exaggerated and focused.

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Your daughter hasn't seen the cracks of course,
Mar 17, 2018 7:04PM PDT

but what does she think of this story?

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link
Mar 17, 2018 7:04PM PDT
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I'll see her tomorrow
Mar 17, 2018 8:37PM PDT

at church, but I probably won't think to ask about it. Maybe she will mention the accident.