Pedestrian Bridge Collapse - Florida International University

[MA_PE]

COA = ???

Just below the PE stamp in the title block  - Florida Certificate of Authorization number.

 

[MA_PE]

so it looks like it did have some type of off set mid support - doesn't look like that part was not in yet - based on any of the photos? defin none of the cable supports - I wonder if this was just a means and methods of constructing issue?

This is my initial inclination. I don't believe that main column and cable supports were just for aesthetics.

 

[knight1fox3]

Just below the PE stamp in the title block  - Florida Certificate of Authorization number.

Ah ok, thanks. I was thinking authentication. :thumbs:

 

[youngmotivatedengineer]

This is my initial inclination. I don't believe that main column and cable supports were just for aesthetics.

The initial reports said that they were tightening support cables that loosened, when the bridge collapsed.  It's possible that the temporary support cables were in adequate or they were over-tightened and ruptured.

 

[Jbone27 PE]

or is the structure on the left side of the photo above the mid span support? I guess that's the canal off the page?

That's the way I'm seeing it.  Part that collapsed was spanning from station 10+00 to the pylon at 11+75?

 

[Road Guy]

I wonder if the contractor has some type of RFI where they asked the engineer "hey can we install the southern span before installing the cable support structure"?

 

[youngmotivatedengineer]

Here is link to news story that has dash cam footage of the actual collapse.

http://newjersey.news12.com/story/37783534/new-video-shows-pedestrian-bridge-collapse-on-florida-college-campus

 

[csb]

HFS! That was intense! I'm realizing that the capture rate on the camera was set kinda weird, but that sucker just flat hit the ground. 

 

[TheNiloJunior]

That's the way I'm seeing it.  Part that collapsed was spanning from station 10+00 to the pylon at 11+75?

Yeah, they only installed the span from 10+00 to 11+75, so that support in the middle of the elevation is what you're seeing on the left of the posted photo.

 

[TheNiloJunior]

I wonder if the contractor has some type of RFI where they asked the engineer "hey can we install the southern span before installing the cable support structure"?

That'd be something. Also, to make their case like any good contractor would do, if it's followed up with the reasoning why installing the span first without any needed supports is a better solution than what was instructed per design.

Not being a bridge guy myself, seeing a sequence of construction plan will really clear up the question to folks on if the span was placed before any needed temporary or permanent supports or if the slab post tensioning was all that was called for to keep the span in place temporarily and the structure was installed per the approved sequence.

 

[Road Guy]

anyone have a link to the full plans?

I've only built normal bridges but those don't normally include any sequencing - covered in standard specs, but I would like to think something like this would have some more detailed phasing, do this before that, etc - since its most likely not covered under FDOT's typical specifications.

 

[MA_PE]

I don't know if the plans are available to the public or posted online.  If for no other reason than traffic (autos and pedestrians) the construction sequence must have been fully defined.  this is definitely not a "typical" bridge that would fall under Standard specifications.

 

[Road Guy]

I agree & that's why Id like to see the plans, its a public project so they should be out there somewhere - 

Usually even for (normal) bridges over the interstates its not very specific, "Contractor shall not place beams while the road is open to traffic" type stuff  But rarely have I seen Step1 - Do this, Step 2 - Do this, etc...

But I imagine for this particular bridge set up there would be more detailed steps / specs to construct..

 

[MA_PE]

Maybe...maybe not.  This was an ABC so there might be lots of contact between the designer and the contractor.  Clearly there was a LOT of coordination in performing the actual placement.  The vehicle(s) used to rotate and lift in place were pretty dang impressive.   The placement was so high profile  that I don't see a lot of room for surprises, all of the necessary personnel had to be aware of what was going on and how it was being done.  The rumor mill (aka the news stories) are claiming last minute changes, blah, blah.

And then there's this guy from Canada



I tend to wait for facts.

 

[kevo_55]

I think I got dumber by watching that video.

 

[goodal]

"I'm not an engineer but..."  

 

[Road Guy]

Anyone notice the construction worker on top of the bridge when it collapsed? I hope that guy was OK, it did not appear that he was tied off

 

[BamaStrucPESE]

anyone have a link to the full plans?

I've only built normal bridges but those don't normally include any sequencing - covered in standard specs, but I would like to think something like this would have some more detailed phasing, do this before that, etc - since its most likely not covered under FDOT's typical specifications.

https://facilities.fiu.edu/projects/BT_904/MCM_FIGG_Proposal_for_FIU_Pedestrian_Bridge_9-30-2015.pdf

 

[Road Guy]

interesting thanks!

Page 14 seems to indicate the "stay pipes" (cables?) are not required for structural requirements - but are an additional member for "natural frequency requirements"

I didn't realize until this link that this was a design build job - defin makes it more interesting as their shouldn't have been much back and forth over means and methods like in DBB.

that is one excellent looking proposal though - probably there is some less sexy one that provided a bridge that didn't fall down for a few million less that didn't get selected..

 

[tj_PE]

I'm bummed I won't be able to hook up a hammock between the diagonals.