Pedestrian bridge collapses at FIU

mj4cy

Asst. Regional Manager
Staff member
Mar 28, 2006
31,816
14,784
113
Iowa
I'd imagine the bridge would have been modeled and checked for stresses, right, structural guys?


Yeah it would be impossible to build a bridge without extensive design conforming to AASHTO and a thorough 3rd party review.
 

CtownCyclone

Midnight Rider
SuperFanatic
SuperFanatic T2
Jan 20, 2010
16,834
9,130
113
Where they love the governor
  • Agree
Reactions: aauummm

mj4cy

Asst. Regional Manager
Staff member
Mar 28, 2006
31,816
14,784
113
Iowa
There are so many sinkholes in Florida, I would wonder about solid footings for the bridge. It’s developing a swamp.

They would have had geotechnical exploration way ahead of the time before putting a shovel in the ground. It appears to be a superstructure issue, not a substructure issue at this point. Scary stuff.
 

CtownCyclone

Midnight Rider
SuperFanatic
SuperFanatic T2
Jan 20, 2010
16,834
9,130
113
Where they love the governor
Yeah it would be impossible to build a bridge without extensive design conforming to AASHTO and a thorough 3rd party review.

That's what I figured. I'd guess something construction-wise was amiss, especially if they had gotten behind schedule and were trying to catch up and missed something.
 

mj4cy

Asst. Regional Manager
Staff member
Mar 28, 2006
31,816
14,784
113
Iowa
That's what I figured. I'd guess something construction-wise was amiss, especially if they had gotten behind schedule and were trying to catch up and missed something.

With suspension/post tensioned bridges of that nature....the game these days is to maximize efficiency and push things to the limits. So if the design or construction is a little off, it can cause a domino affect.
 

Cyclones_R_GR8

Well-Known Member
SuperFanatic
SuperFanatic T2
Feb 10, 2007
23,959
25,941
113
Omaha
On the news they said there are 8 vehicles trapped beneath the rubble. Now they are scrambling to get heavy equipment down there to try to start cleaning up.
 

ArgentCy

Well-Known Member
Jan 13, 2010
20,405
11,148
113
This looks like some sort of major flaw in the installation plan. They just put this section into place last Saturday. Now judging from the model there are supposed to be suspension cables to support the entire structure but those weren't in yet. So it appears they removed all the supports holding it up so traffic could continue on Monday leaving that long span to just support itself.

https://news.fiu.edu/2018/03/first-of-its-kind-pedestrian-bridge-swings-into-place/120385

View attachment 54003

Well you don't have to be an engineer to figure this problem out. WTF.
 
  • Agree
Reactions: khardbored

BoxsterCy

Moderator
Staff member
Sep 14, 2009
48,330
47,253
113
Minnesota
Pretty strange. What was moved into place looks like an artistic expression of a stylised truss but those models make it look like a suspension.

Anyway, for something to collapse during construction like this is a major fuckup.
 
Last edited:

Knownothing

Well-Known Member
Nov 22, 2006
16,649
8,718
113
51
This makes no sense. I don't know how this could possibly happen in todays world. Honestly, Its sad but someone will need to pay the price for not getting it done right on a college campus.
 

CyArob

Why are you the way that you are?
Apr 22, 2011
32,496
13,442
113
MN
I wonder if there is a time lapse video of the construction. Those are very common on "innovative" projects like this.
 

mj4cy

Asst. Regional Manager
Staff member
Mar 28, 2006
31,816
14,784
113
Iowa
Well you don't have to be an engineer to figure this problem out. WTF.


Reading this article more and more, I think the macro design is just fine. That model in the picture could have been one solution, but it appears the final solution was a large truss. My guess is the problem is in the details, I just don't know if it was a design flaw or construction flaw.

If you think about it, skywalks go 100+ feet sometimes and they're basically just huge trusses more or less that rely on tension/compression force transfer through its members.
 
  • Agree
Reactions: aauummm

mj4cy

Asst. Regional Manager
Staff member
Mar 28, 2006
31,816
14,784
113
Iowa
As a bridge engineer, this is the stuff of my nightmares.

That's why I got into building design out of college :)

Now I do construction structural engineer. Most of what I design is only temporary!
 
  • Friendly
Reactions: DeftOne

DeftOne

Well-Known Member
Dec 30, 2014
790
472
63
Des Moines, IA
Reading this article more and more, I think the macro design is just fine. That model in the picture could have been one solution, but it appears the final solution was a large truss. My guess is the problem is in the details, I just don't know if it was a design flaw or construction flaw.

If you think about it, skywalks go 100+ feet sometimes and they're basically just huge trusses more or less that rely on tension/compression force transfer through its members.
It was still going to be a cable stayed bridge in its final state. You can see the cable connection points on top.
 
  • Informative
Reactions: NWICY and mj4cy

ArgentCy

Well-Known Member
Jan 13, 2010
20,405
11,148
113
They probably don't allow 50% safety factors like they taught in Statics 101. That is just a bit too expensive in the real world.