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OT Miami Walking Bridge Collapse

CatMan

Hot Rolled
Joined
Apr 12, 2005
Location
Brandon, MS
Companies behind Florida bridge collapse have history of fines, failures, lawsuits | Fox News

I'm sure most of the world is aware of this awful failure by now.

But my question is, how did this happen? I know it may take months of going through the rubble to find out or we may never know. The bridge weighed 950 tons and spanned a 7 lane highway. It was made on the side of the road and then moved into place. Everything seemed to be fine and then it collapsed five days later.

What do you think happened? This was just a pedestrian bridge that wasn't even in use yet. It's not like it was overloaded.

Concrete wasn't fully cured? Tension cables weren't tightened sufficiently (as I have read in other articles)? Got too cute with trying to make the bridge pretty? Cutting corners in construction? Didn't design it strong enough in efforts to save money? Didn't account for wind load?

I've seen some engineering failures, but this one happened so soon I'm puzzled by it.
 
I saw a headline that said the bridge was built using some sort of corner-cutting technology.


"The pedestrian walkway that collapsed Thursday in Miami, killing at least six people, was being built using a popular but relatively new bridge technology specifically designed to speed construction while maintaining safety.

It took only six hours on Saturday to install the 174-foot pedestrian walkway, part of the 320-foot-long FIU-Sweetwater University City Bridge project at Florida International University"
 
When completed it would have been a center pylon cable stayed suspension bridge. Kinda strange to install the suspension AFTER the deck. I'm guessing the number of trial lawyers on site far exceeds the number of rescue workers..........Bob
 
I talked to an engineer friend about the failure and mentioned my dismay at the design. It was a perfect application for a composite (polymer) bridge, and to have made it from concrete and steel when it's so close to an ocean (salt) environment is foolish IMO.

The other aspect that's troubling is that the final structure included a central pillar (under compression) which was to have tension cables anchored at the center of the walkway along it's length. Properly done, these would have supported the bridge section that collapsed, but only one side of the bridge was in place, therefore not allowing the "balance" of having the tension cables on both sides of the pillar.

Tragic, foolish, and so very sad for the families of the dead and injured.
 
Bob beat me on the pillar. One other aspect of this is that when looking at the main span (the lower walkway), it seems that there's major length-wise tensioning elements near the upper surface of the structure, which indicates that the entire span was really meant to be in compression, hanging from the stay cables from the central pillar.

So having no temporary central supports under the structure before the entire span is complete (and properly supported) becomes even more incomprehensible.
 
There is an excellent discussion on The Hull Truth Site about this bridge. In "Dockside Chat" section of The Hull Truth.

The Hull Truth (THT) is a boating and fishing forum, a lot of Florida folks hang out there. A lot of photos and links are on THT of the bridge, both before and after the failure. And some excellent details of what went wrong. Many of the THT members know this bridge well and live in the area.
 
Local news this morning said that the same company made a exact same bridge about 5 years ago in Sacramento, California. I could find no confirmation.
Bill
 
If the center section wasn't in place yet, why were people allowed to drive under it ?

I understand the pressure to eliminate falsework, but not when
the road underneath is open.

"Jack Up Slab" construction got cheapened up to a point where
a catastrophic failure banned the practice here in the USA.
 
I have an idea. Let's crack open a beer, lean back in the lazyboy, and speculate our asses off.

Um...there's speculation then there's open discourse. The idea that no one should talk about it 'until all the facts are known' is kinda lame, especially considering it will be years before all the facts are in and when they are in, you won't be privy to them. And let's not forget that all the facts will NEVER be in because we've learned by now that even the most in-depth analysis will contain lots of 'probably' and 'most likely' statements. Most of all, we're talking about a physical failure which can be tied to known physical attributes and properties...it's not like we're speculating about who shot Kennedy or why Brad and Angie split up.
 
Um...there's speculation then there's open discourse. The idea that no one should talk about it 'until all the facts are known' is kinda lame, especially considering it will be years before all the facts are in and when they are in, you won't be privy to them. And let's not forget that all the facts will NEVER be in because we've learned by now that even the most in-depth analysis will contain lots of 'probably' and 'most likely' statements. Most of all, we're talking about a physical failure which can be tied to known physical attributes and properties...it's not like we're speculating about who shot Kennedy or why Brad and Angie split up.

Even if every member of PM were a licensed Civil Engineer, which is far from the case, any discussion of why the bridge collapsed is mindless speculation.
 
"The designers would have created temporary supports for the large section installed Saturday to hold until it was connected permanently to the structure’s columns and foundation, according to Amjad Aref, a professor at the University at Buffalo’s Department of Civil, Structural and Environmental Engineering.

“In layman’s terms, it’s actually flimsy before it’s complete," Aref said."

Given that the above is factual one does have to wonder that they gambled with the lives of the public under those circumstances, sort of like saying "This airplane we are flying could fall apart in the sky until the spars are installed, in layman's terms."
 








 
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