Author Topic: Florida Bridge collapse  (Read 7014 times)

230RN

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Re: Florida Bridge collapse
« Reply #25 on: March 16, 2018, 04:12:04 PM »
Closed circuit tv of the actual collapse at 0:30

https://youtu.be/F0MBOQV7kuU

Don't know if it's been posted before.

Hawkmoon

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Re: Florida Bridge collapse
« Reply #26 on: March 16, 2018, 07:20:01 PM »
Thank you, Captain Obvious:

http://www.newser.com/story/256681/florida-bridge-collapse-may-lead-to-criminal-charges.html

Quote
One thing investigators are looking at is if it was a good idea to install the 174-foot bridge before the central tower.

Offhand, I think we can now conclude that it probably was not a good idea.
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MechAg94

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Re: Florida Bridge collapse
« Reply #27 on: March 16, 2018, 09:45:50 PM »
Closed circuit tv of the actual collapse at 0:30

https://youtu.be/F0MBOQV7kuU

Don't know if it's been posted before.
Just curious how y'all see it.  It almost looked like it cracked in 2 or 3 spots then it started folding up fell. 
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Hawkmoon

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Re: Florida Bridge collapse
« Reply #28 on: March 16, 2018, 10:07:28 PM »
Do we like smoking guns? Of course we like smoking guns.

https://www.abcactionnews.com/news/state/fdot-warned-about-fiu-bridge-cracking-2-days-before-fatal-collapse-but-didnt-hear-voicemail

Lead project engineer for Figg (the designers of the bridge) called a Department of Transportation employee two days BEFORE the collapse to report unanticipated cracking in the bridge -- near the north end (which is the end toward the center pylon, and thet's where the collapse started).

Quote
"Hey Tom, this is Denney Pate with FIGG bridge engineers. Calling to, uh, share with you some information about the FIU pedestrian bridge and some cracking that's been observed on the north end of the span, the pylon end of that span we moved this weekend. Um, so, uh, we've taken a look at it and, uh, obviously some repairs or whatever will have to be done but from a safety perspective we don't see that there's any issue there so we're not concerned about it from that perspective although obviously the cracking is not good and something's going to have to be, ya know, done to repair that. At any rate, I wanted to chat with you about that because I suspect at some point that's gonna get to your desk. So, uh, at any rate, call me back when you can. Thank you. Bye."

I think Figg is fubar on this one.
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Fly320s

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Re: Florida Bridge collapse
« Reply #29 on: March 17, 2018, 06:50:51 AM »
Just curious how y'all see it.  It almost looked like it cracked in 2 or 3 spots then it started folding up fell.  

I couldn’t tell.  There is another video out from someone’s dashcam in their car that is better quality.

Found it:  https://m.youtube.com/watch?v=Ucflj-MsJBI
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Fly320s

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Re: Florida Bridge collapse
« Reply #30 on: March 17, 2018, 06:53:54 AM »
I only see one spot where the bridge breaks, which is right next to the crane.  Maybe the crane boom hit the bridge. 
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K Frame

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Re: Florida Bridge collapse
« Reply #31 on: March 17, 2018, 07:53:23 AM »
I'm sure that Mr. Pate will be the scapegoat for all of this.
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Hawkmoon

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Re: Florida Bridge collapse
« Reply #32 on: March 17, 2018, 11:06:53 AM »
The bridge deck broke at the intersection of two of the diagonal truss members. This is called a truss "panel point," and it's where stress concentrates in a truss. The roof broke at the upper panel point.

Video report on the phone call: https://www.youtube.com/watch?v=FNrAMYxp8CE

Being an olde pharte who has lived through several infamous collapses and read the reports on the causes, I'm baffled at the hubris that led them to open the road to traffic under a bridge that didn't have the structural cable system in place.

In April of 1987, a 16-story building was under construction in Bridgeport, Connecticut. The structural system was called "lift slab." In this system, the concrete floor slabs are all poured on the ground, one on top of another like a stack of pancakes. Once they're cured, they are hoisted up and clipped in place to the vertical columns. At L'Ambiance Plaza, something went wrong and one of the slabs came crashing down, taking down the entire structure and killing a number of workers who were under it. In the aftermath, Connecticut enacted a moratorium on lift slab construction (which may still be in effect), and the industry adopted rules that only essential workers are allowed under the slabs while they are being hoisted and secured.

This bridge is kind of the same idea. Instead of "lift slab," it's a "lift bridge." The idea of building bridges off to the side and then dropping them into place is not new, but in this case the bridge they dropped into place was NOT the complete structure. The completed structure would have included the central pylon (which hadn't even been built yet), the other span (across the canal), and the cables connecting and supporting the two spans. Obviously, someone thought the truss was structurally sufficient without the cables. That calculation was obviously incorrect. (Either that, or there was a massive flaw in the construction. That's possible, but probably unlikely.)

I just can't believe they opened the road to traffic with the structure not fully in place.
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dogmush

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Re: Florida Bridge collapse
« Reply #33 on: March 17, 2018, 02:44:59 PM »
Here's an interesting video discussing what can be gleaned from pictures and video.

https://youtu.be/KtiTm2dKLgU

AVE is a smart guy, and lots of engineers have been kicking this around on the internet. I think their theory is compelling. i.e. the crew was messing around with the post tensioning rods and they failed.

I read a report that they were doing a stress test, and had cranked up the tension on the rods for the test.

Hawkmoon

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Re: Florida Bridge collapse
« Reply #34 on: March 17, 2018, 03:43:15 PM »
The explanation in the AVE video makes a lot of sense.
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Pb

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Re: Florida Bridge collapse
« Reply #35 on: March 19, 2018, 10:13:43 AM »
Somewhere, I read that in Roman times, engineers were required to stand under a new bridge as supports were removed... hmmm...

MechAg94

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Re: Florida Bridge collapse
« Reply #36 on: March 19, 2018, 10:57:49 AM »
Somewhere, I read that in Roman times, engineers were required to stand under a new bridge as supports were removed... hmmm...
It collapsed a week later.  Unless the engineers were going to live there, that wouldn't work well.   =D
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K Frame

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Re: Florida Bridge collapse
« Reply #37 on: March 19, 2018, 11:19:36 AM »
Surprised no one has posted video of this yet. The Tacoma Narrows Bridge collapse.

https://www.youtube.com/watch?v=CsKKDLKYsVU

This is a true failure of design and engineering.

No human deaths, apparently a dog was left in one of the cars and died when the driver abandoned it to run back to safety (why the ahole didn't drive is beyond me).
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Perd Hapley

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Re: Florida Bridge collapse
« Reply #38 on: March 19, 2018, 12:09:04 PM »
No human deaths, apparently a dog was left in one of the cars and died when the driver abandoned it to run back to safety (why the *expletive deleted*hole didn't drive is beyond me).


My first guess is that he believed he'd be safer on foot, instead of in a much heavier car. In the film, though, he seems to be walking off slowly and calmly. Maybe he just didn't care about the dog.  =(
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230RN

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Re: Florida Bridge collapse
« Reply #39 on: March 19, 2018, 12:20:24 PM »
Somewhere, I read that in Roman times, engineers were required to stand under a new bridge as supports were removed... hmmm...

"AAACK!  It was supposed to be III.I,IV,I,V,IX, you idiot, not III.I,VI,I,V,IX !"

Hawkmoon

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Re: Florida Bridge collapse
« Reply #40 on: March 19, 2018, 12:27:44 PM »

My first guess is that he believed he'd be safer on foot, instead of in a much heavier car. In the film, though, he seems to be walking off slowly and calmly. Maybe he just didn't care about the dog.  =(

I don't think the guy in the film was the driver of the car. I think that was an engineering professor who showed up to investigate the bridge's behavior. I think his name was Farquharson, or something like that.

First-hand accounts: http://www.wsdot.wa.gov/TNBhistory/People/eyewitness.htm

The narrator says the Bronx-Whitestone bridge in New York is a twin, but it isn't. Galloping Gertie was two lanes wide -- the Whitestone is six lanes. (Four lanes plus pedestrian walkways when it was opened, converted to six vehicular lanes since.)
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K Frame

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Re: Florida Bridge collapse
« Reply #41 on: March 19, 2018, 12:39:43 PM »
"AAACK!  It was supposed to be III.I,IV,I,V,IX, you idiot, not III.I,VI,I,V,IX !"

Took me a second, but that's pretty good!  :rofl:
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Perd Hapley

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Re: Florida Bridge collapse
« Reply #42 on: March 19, 2018, 12:56:30 PM »
Took me a second, but that's pretty good!  :rofl:

I thought they were just random numbers, but I see what you mean.
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230RN

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Re: Florida Bridge collapse
« Reply #43 on: March 19, 2018, 01:01:09 PM »
...

I was about to bring up a trip by bus my mother and I took to the Bronx to visit my sister when I was, I dunno, seven or eight yo during a windstorm.  I'm pretty sure it was the Whitestone Bridge or one of the Triborough bridges.  Thanks for the reminder.  That bridge was whipping all over and the driver was really struggling to keep the bus on course.

Really scared the crap out of me and my Mom and the other passengers.  I don't remember if it was a near hurricane or what, but the first time I ever saw that Tacoma Bridge video, it was just like that, with the pavement bending like rubber but maybe not as bad.  So I'm not surprised that the guy left the car.  I wondered about that dog, too.

Terry


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Re: Florida Bridge collapse
« Reply #44 on: March 19, 2018, 08:30:14 PM »
Surprised no one has posted video of this yet. The Tacoma Narrows Bridge collapse.

https://www.youtube.com/watch?v=CsKKDLKYsVU

This is a true failure of design and engineering.

No human deaths, apparently a dog was left in one of the cars and died when the driver abandoned it to run back to safety (why the *expletive deleted*hole didn't drive is beyond me).

I think I remember reading somewhere that he had tried to go back for the dog but couldn't.
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K Frame

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Re: Florida Bridge collapse
« Reply #45 on: March 20, 2018, 10:19:07 AM »
I did some more reading on it, and yes, he and another person did try to go back to the car to get the dog. Apparently it was so terrified that it bit him or the other guy when they tried to get it out of the car.
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just Warren

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Re: Florida Bridge collapse
« Reply #46 on: March 20, 2018, 12:06:44 PM »
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Pb

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Re: Florida Bridge collapse
« Reply #47 on: March 20, 2018, 12:13:53 PM »
Why didn't they use something like this?

Yeah no kidding!  Would have been a lot simpler, and cheaper!

I guess it wouldn't glorify an administrator's ego to build something small like that.

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dogmush

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Re: Florida Bridge collapse
« Reply #49 on: March 20, 2018, 01:14:07 PM »
Why didn't they use something like this?

I suspect you'd find an aluminum truss couldn't span the distance they needed and also hold the weight of anticipated pedestrian traffic.  Obviously this particular concrete truss couldn't either, but in general a stressed concrete (either pre- or post-) is a good, low maintenance, strong, relatively cheap answer to bridging things.

The GatorBridge website you linked shows a bridge in Oakland that has several support piers and spans 120'.  It is described as "one of the larger structures fabricated by [....] Gator [bridge]".  That prefab aluminum stuff is a completely different scale.