breaking news- bridge collapse in Miami

[MA_PE]

Brand new pedestrian bridge just set in place this past sunday and not yet open to the public.  Wow.  heads will roll for this one.

https://www.nbcnews.com/news/us-news/miami-pedestrian-bridge-collapses-trapping-unknown-number-people-n857011

 

[Ble_PE]

That's crazy! I'll be interested to see what happened seeing as how they had only placed it on Saturday. I wonder what started the collapse. 

 

[Dleg]

Looks terrible. 

 

[knight1fox3]

Well that's pretty terrible! I assume since this was a structural component design, there's likely a corresponding PE that signed/sealed the plans, yes?

 

[Road Guy]

I can't tell from the pictures but it looks like it had concrete girders? Wonder if they were fabricated wrong? This is why those weasel SE's stamp them "no exceptions taken" instead of approved..


We had a conspan bridge ( for a one lane road) that was fabricated incorrectly, they basically had all the metal supports in the wrong location, I don't remember the technical term for which member it was , but I'm glad our inspector caught it. It was a huge deal.

I made the contractor remove it and get a new one, it was pretty damn expensive for them I imagine.

 

[Dexman PE PMP]

Yes, a PE signed off on the design, but that doesn't necessarily guarantee that the contractor's methodology was correct.  Looks like the super-structure was built off-site and put in place within the last week or so. I'd be curious to see if it was a failure of the support structure or of the super-structure itself failed.  Then it would need to be determined if it was a product of the design or if the contractor messed something up.

Regardless, no one involved wanted this to happen.

 

[Road Guy]

Scrolled down further - I've never seen this style of ped bridge ? Is that like a steel truss in the middle that holds up the deck?

 

[Dexman PE PMP]

We had a project get circulated internally to advise the importance of full quality reviews of drawings during the construction process.

Long-story short, designer had designed a steel truss platform for a storage tank. There was a design change during construction and a CAD tech accidentally deleted some linework or turned a layer off while adjusting something else nearby (essentially removing a cross-member), but when the plans were reviewed the QA reviewer only looked at the bubbled design change and didn't re-evaluate the full design. Basically, the structure was built without the proper bracing but luckily was caught before the tank was installed. Had it been placed, the structure would have collapsed.

 

[MA_PE]

We had a project get circulated internally to advise the importance of full quality reviews of drawings during the construction process.

Long-story short, designer had designed a steel truss platform for a storage tank. There was a design change during construction and a CAD tech accidentally deleted some linework or turned a layer off while adjusting something else nearby (essentially removing a cross-member), but when the plans were reviewed the QA reviewer only looked at the bubbled design change and didn't re-evaluate the full design. Basically, the structure was built without the proper bracing but luckily was caught before the tank was installed. Had it been placed, the structure would have collapsed.

that's where electronic drafting is dangerous.  It's not totally unreasonable for the reviewing engineer to review changes to previously reviewed drawings and not check every line and instead just check the clouded changes.  Glad someone caught that.

 

[MA_PE]

Scrolled down further - I've never seen this style of ped bridge ? Is that like a steel truss in the middle that holds up the deck?

It looks like that is the main structural system. this bridge is pretty big.  I wonder if fabrication/assembly was accelerated too and things didn't get cured properly.  This is a Miami installation and the bridge was supposedly designed to withstand major hurricane forces.

Collapsed images suggest the top chord buckled in compression.

 

[NJmike PE]

 

[Dleg]

Ouch.

 

[MA_PE]

I think I'd delete that too.

 

[tj_PE]

yikes

 

[tj_PE]

apparently it was designed as a cable-stayed bridge? 

which brings up some questions

did the SE underdesign the concrete to support its own weight during construction? was it supposed to be shored? surely not since it's over a roadway? Was it unstable? 

 

[leggo PE]

This is so sad to hear. I'll be very interested to hear what the cause of the collapse was. Seeing how it wasn't even open to the public yet, I feel it must have been related to either the design the bridge (i.e. like @tj_PE said, perhaps it wasn't properly designed to support the proper construction loads), or fabricated/installed incorrectly.

But good grief. Something definitely went terribly wrong here.

 

[tj_PE]

yeah. looking at the collapsed pic, it looks like maybe the bottom connection of the slab to the vertical end post and support slipped off or failed, which put extra and likely somewhat dynamic weight on that second panel point of the truss and it snapped :/

 

[Ramnares P.E.]

Terrible to say, but this bridge collapse will help bolster on-going NSPE cases against states that want to de-legitimize the importance/requirement for PE licenses.  A timely but tragic reminder of the consequences of poor engineering design/oversight.

 

[Supe]

did the SE underdesign the concrete to support its own weight during construction? was it supposed to be shored? surely not since it's over a roadway? Was it unstable? 

My first thought mirrored MA's - possible curing/concrete issues, but when I read what the design was supposed to be and saw "cable-stayed", that was absolutely my next though.

Reminds me of a power plant job we had where the firm who designed the piping and supports forgot to account for the added water weight for hydrotest.  Didn't find out until some smaller structural members began bending under the weight and all the hanger adjustments were maxed out.

 

[mudpuppy]

Terrible to say, but this bridge collapse will help bolster on-going NSPE cases against states that want to de-legitimize the importance/requirement for PE licenses.  

Which might help for a while, but the anti-regulation party is already trying to roll back the PE requirements for drill rigs that were strengthened after Deepwater Horizon.

https://www.nspe.org/resources/pe-magazine/march-2018/nspe-fights-dangerous-attempt-roll-back-deepwater-horizon-safety