Miami pedestrian bridge collapse

[California]

After seeing a lot of confused nonsense on national media I found an intelligent discussion of the Miami pedestrian bridge collapse, over on Welding Web.

A photo of the model shows the weight will be carried by cables - from a central tower that was going to be built after the decks were placed.

And a post saying the failure came after the post-stress rods (cables?) were re-tightened. One theory is that a rod snapped during re-tightening.

I haven't seen a rational, engineering-based explanation like this anywhere else yet. There seem to be contributors with an engineering background posting in that thread.

Miami pedestrian bridge installed on Saturday. Collapsed today.

 

[/pine]

In some parts of the world...engineers can face the death penalty when they are found negligent...I imagine there will be some back and forth between the engineering firm and the contractor(s)...

 

[ovrszd]

In my opinion the negligence is stress testing with traffic going underneath. I don't understand that at all.

 

[California]

In some parts of the world...engineers can face the death penalty when they are found negligent...

Yeah. It turned out to be a true rumor that the principals of the engineering firms who built multi-story apartments that fell in the 1967 Caracas earthquake, were on the plane home to Italy before anyone knew their names. A 9 story building that pancaked was across the street and down a block from our Caracas office. Thankfully I was in the far end of the country - Maracaibo - when it happened.

Later analysis showed the 'concrete' was way out of spec - a gross failure of construction inspection indicating bribes were more important than safety.

 

[Stimw]

Negligence started when the idiots decided to spend 13 million on a pedestrian bridge when there is a LARGE crosswalk/intersection less than 50' with traffic lights and walk/wait signs!
One student was killed crossing last summer. They are college students and they haven't learned how to cross a street???
How many would not have used the bridge because they would have to walk up steps?
MORE tax and spend!

 

[California]

Dashcam video. At seven seconds it broke near the the left (north?) end then pulled down the entire bridge.

From the Miami Herald.

Instagram video shows collapse of FIU pedestrian bridge | Miami Herald



Another video linked from that page taken from the opposite side. It's clearer that the bridge broke some 10 ft from its pedestal.

Video circulating online shows moment FIU bridge collapses on SW 8th St. | Miami Herald

 

[laurencen]

why did they not support it in the center? pictures of the finished bridge seems to show a center support, if a support was indeed needed then the design was not to single spam the freeway, also why stress test the structure with traffic traveling underneath?

 

[Redbug]

This looks like a criminal engineering blunder. The temporary supports were moved to another place on the bridge because of the embankment and I bet that was not figured into the equation before it was done. An engineering oversight. I don't know if it was true, but I read that Roman engineers in charge of building bridges had to stand beneath them as the scaffolding was removed...

 

[tcreeley]

Negligence or poor design?

"Florida's Department of Transportation says an engineer left a voicemail two days before a catastrophic bridge failure to say some cracking had been found at one of the concrete span.

However, the agency says the voicemail left on a landline wasn't heard by a state DOT employee until Friday because the employee was out of the office on an assignment."

The Latest: Caller reported cracks in bridge before collapse


more -

"A construction firm involved in this week's fatal bridge collapse in Florida was accused previously by a subcontractor of failing to properly design a bridge construction system after an accident in Virginia.

The allegations were made in a lawsuit that was later settled. A confidentiality agreement bars the release of details.
The lawsuit stemmed from FIGG Bridge Group's building of the Southern Norfolk Jordan Bridge in 2012. During construction in Chesapeake, a 90-ton segment fell onto railroad tracks below."

 

[Gale Hawkins]

Negligence or poor design?

"Florida's Department of Transportation says an engineer left a voicemail two days before a catastrophic bridge failure to say some cracking had been found at one of the concrete span.

However, the agency says the voicemail left on a landline wasn't heard by a state DOT employee until Friday because the employee was out of the office on an assignment."

The Latest: Caller reported cracks in bridge before collapse


more -

"A construction firm involved in this week's fatal bridge collapse in Florida was accused previously by a subcontractor of failing to properly design a bridge construction system after an accident in Virginia.

The allegations were made in a lawsuit that was later settled. A confidentiality agreement bars the release of details.
The lawsuit stemmed from FIGG Bridge Group's building of the Southern Norfolk Jordan Bridge in 2012. During construction in Chesapeake, a 90-ton segment fell onto railroad tracks below."

Thanks for that link to the rest of the story.