Florida bridge collapse

[ZenOps]

http://www.bbc.com/news/world-us-canada-43418898

[dirtsniffer]

Damn RIP.

Interested to learn what the root cause was.

[nzwasp]

I feel like a 175 FT bridge should have a supporting column?

[blitz]

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I feel like a 175 FT bridge should have a supporting column?

Peace Bridge is like 400 ft long with no column.

[nzwasp]

Its not made of concrete though.

[mr2mike]

Just shoddy Italian steel and welds.

[Sugarphreak]

...

[Stuart]

we did a little CSI at work and found the following:
-the installed bridge was only half of the final design, the other half was supposed to span the canal beside the road.
-once both halves were installed there was also supposed to be a cable-stay setup, which was no installed yet.

This means that the portion that collapsed was not supported correctly as the load paths were not available as per the design. No wonder it collapsed. Below is a rendering of what is should have looked like.

[Sugarphreak]

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[FraserB]

Haha, that’s ridiculous. And five days after install to boot

Almost as good as some of the decisions on the last job phreak and I were on

[Stuart]

My guess was this was a new "senior" engineers first job as a lead, it's pretty small compared to most that company does. Lack of planning for the full installation and this is what you get.

[rage2]

Wait, what? It was supposed to be a cable stay design but they installed it without the cables that’s there to support the load?

Surprised it lasted 5 days.

Edit - http://www.smobserved.com/story/2018...apse/3368.html

Who does a stress test without closing off traffic?

[ZenOps]

Bridge was designed to endure a Category 5 hurricane, no idea what to make of that.

[BerserkerCatSplat]

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we did a little CSI at work and found the following:
-the installed bridge was only half of the final design, the other half was supposed to span the canal beside the road.
-once both halves were installed there was also supposed to be a cable-stay setup, which was no installed yet.

This means that the portion that collapsed was not supported correctly as the load paths were not available as per the design. No wonder it collapsed. Below is a rendering of what is should have looked like.

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Wait, what? It was supposed to be a cable stay design but they installed it without the cables that’s there to support the load?

Surprised it lasted 5 days.

Edit - http://www.smobserved.com/story/2018...apse/3368.html

Who does a stress test without closing off traffic?

According to the design proposal documents, the cable stays were basically ornamental and only provided vibration damping. Each deck section was designed to be completely self-supporting and placed with SPMTs without need for temporary bracing that would have screwed up traffic.

I can't imagine why a dynamic-drop load test would be done on a bridge span, least of all with an operating roadway. I bet a static load test was going to occur later that day and one of the test loads fell from the crane as they were moving it to a staging area.

[Cagare]

A little early to proclaim the cause. This was being done as a design build rapid construction. Likely there is a lot of prefabricated pieces that go with it. Could be a lot of failure mechanisms there. Also, in a design build arrangement, especially when DOT is involved there is likely a separate engineering firm performing qa on the design, on top of internal quality reviews.

Not saying it could not of been a design issue, but not that likely. Will be interesting what is uncovered.

[Sugarphreak]

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[Sugarphreak]

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[BigDL]

The idiot that decided to do the test with the road still open during rush hour should be shot, I am not an engineer but that sounds like the most stupid thing ever, herp derp lets do this now with people driving under the bridge, nothing bad could ever happen if something failed!

[BerserkerCatSplat]

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Just looking at it, the shape of the bracing is very clearly designed to be transferring load to the cables. Otherwise it would have been more uniform.

Or the supports were clearly designed to look good lined up with the cable stays for a coherent design. Could go either way.

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One more post:

So in this video you can see how the set the bridge on the pier. Basically there was no connection at all aside from those two small posts you can see in the photo above. The reinforcing that sticks up goes around the vertical column.

Good effort, but there's actually a security cam video of the failure floating around. It failed midspan off to one side, not on the pier edge.

https://imgur.com/gallery/es4vo


Some sources are saying the slab tension had slackened after installation and a company (Structural Technologies, one of their trucks was parked under the span and was crushed) was on-site retensioning the slab when the bridge failed. You can see stressing jacks in the aftermath photos that were in place when the collapse happened. Lots of rumours flying around, though.

[ExtraSlow]

Lotta bridge experts on beyond. I did not know that.