Florida International University pedestrian bridge collapse

[Gawdzilla Sama]

It was apparently designed for a service lifespan of 100 years and survive category 5 hurricane. AFAIK, 100 years have not lapsed since last saturday, nor has any hurricanes graced Florida.

Dunno, T.rump has been in office for a millenium. 

[Minimalist]

'murrican engineering.

The French built this.



WTF is wrong with us?

[vorlon13]

Saw an item in another forum a crane in use at the time may have had a problem. (snapped cable)

This is unverified so far.

[Anomalocaris]

'murrican engineering.

The French built this.



WTF is wrong with us?

They have bridges in the clouds, we have heads in the clouds.

[vorlon13]

The Milau Viaduct is a beautiful bridge, I'll grant that. Videos of it being constructed are some of the most scary, vertiginous scenes I've ever encountered.

As for the pedestrian overpass, a 950 ton, 174 foot long structure is pretty remarkable. A local truss bridge in this area is probably over 100 years old, spans 185 feet, and couldn't weigh more than 50 tons . . . . .

[Anomalocaris]

The Milau Viaduct is a beautiful bridge, I'll grant that.  Videos of it being constructed are some of the most scary, vertiginous scenes I've ever encountered.

As for the pedestrian overpass, a 950 ton, 174 foot long structure is pretty remarkable.  A local truss bridge in this area is probably over 100 years old, spans 185 feet, and couldn't weigh more than 50 tons . . . . .

This is suppose to be a cable stayed bridge.   I see no evidence of the central pylon and cables in the wreckage.  So the bridge was incomplete and seem to lack its main structural support.

Without the suspension cables that put the entire bridge in compression, the bridge surface and the roof would act like a truss beam, with lower bridge surface under tension and upper roof under compression.    Concrete does not so well under tension.   Concrete structure meant to withstand tension needs to be put under pre-compression using tension cables.   This bridge probably doesn’t have tension cables  in its lower surface since the suspension cables, when installed, would play that role.

Since this is a pedestrian bridge, it is probably not designed to withstand any great live load.  Most of the bridge’s designed load would be its own dead weight.  So even before the bridge is finished, the incomplete span’s own weight probably already loaded it to a large percentage of the completed structure’s total designed capacity.

So I bet the bridge was collapsed because it was never designed to sit like a beam between its supports without suspension cables in place to help carry the weight and also put bridge surface under compression. So it probsbly always required the suspension cables to resist its own dead weight.

[Succubus]

Bridge wasn't even completed.  Reports are it was either being tested or post tensioned when it failed.

What's left of it is a rather striking precast steel reinforced concrete structure.  Apparently made off site and erected last Saturday.  Approaches unfinished.

Stress testing a new structure over an open road system? Some people are in for a good fucking and or jail.

[Angrboda]

So I bet the bridge was collapsed because it was never designed to sit like a beam between its supports without suspension cables in place to help carry the weight and also put bridge surface under compression. So it probsbly always required the suspension cables to resist its own dead weight.

I bet this is punishment for the gays.

[Fireball]

Bridge wasn't even completed.  Reports are it was either being tested or post tensioned when it failed.

What's left of it is a rather striking precast steel reinforced concrete structure.  Apparently made off site and erected last Saturday.  Approaches unfinished.

Stress testing a new structure over an open road system? Some people are in for a good fucking and or jail.

Yeah, that's not the way to do it. But I don't think that that was its first stress test. I will tell you that when I worked in a certain contractor's hangar at Cape Canaveral (many years ago), we were told to immediately land our payload and stop using the bridge crane. It was red-tagged during inspection because none of the fasteners on the main rails were ever tightened. I don't mean not spun up to contact, and not tightened properly. There were some nuts that had never been run into contact with the structure; this was evident by the corrosion on the bolts. This crane had been there and in use for 3 years at the time. So, no initial inspection, and two subsequent annual "inspections" where the problem was not noted. Lifting trop cher space flight hardware with unsafe equipment. Tsk, tsk, tsk.

[c172]

Four dead, two critical so far, according to local outlets.