https://www.miamiherald.com/news/lo Four years after fatal collapse, Florida unveils design for 3

[kevinsnn]

https://www.miamiherald.com/news/lo...7412.html?utm_medium=email&utm_source=rasa_io

 

[pegarrett]

I will never understand why owners are so in love with fake cable stays. It's the bridge equivalent of putting a fake ram scoop on a car hood.

Philip E. Garrett, P.E.
Structural Engineer

 

[hokie66]

I agree, but why do you think they are fake?

 

[phamENG]

Making those spindly towers work without stay(s) on the other side might be a bit difficult. But then, it's an artist's rendering, and they didn't say how far along it is in design. I'm guessing it hasn't been through much rigorous engineering yet. After all, those girders are really shallow to span across by themselves. Now if they went with a truss the full depth of the walkway and aligned diagonal web members with the cables, then I could see it working with 'fake' cable stays.

 

[pegarrett]

I agree, but why do you think they are fake?

Concrete is awful in bending. So in order for those towers not to snap in half there should be stays on the backside of the towers to turn the bending load into axial load.

Philip E. Garrett, P.E.
Structural Engineer

 

[pegarrett]

Making those spindly towers work without stay(s) on the other side might be a bit difficult. But then, it's an artist's rendering, and they didn't say how far along it is in design. I'm guessing it hasn't been through much rigorous engineering yet. After all, those girders are really shallow to span across by themselves. Now if they went with a truss the full depth of the walkway and aligned diagonal web members with the cables, then I could see it working with 'fake' cable stays.

The article states that they are using steel girders. From the scale of the people in the rendering it looks like the girders are just about the correct span to depth ratio. They could also be doing a thru girder on either side and have the deck supported by floor beams. Like a railroad bridge.

The "cable stay" towers have a really long unsupported length that is going to be subject to a large bending load if those "stays" are functional.

Prefabricated steel trusses meant for use as pedestrian bridges are cheap and ubiquitous. There is no need to reinvent the wheel. Especially if your new invention is ugly.

Philip E. Garrett, P.E.
Structural Engineer

 

[dik]

The cable stays were supposed to be decorative, but they were capable of sustaining a huge load. They weren't detailed like they were decorative.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[dik]

Was anyone held accountable for the first collapse?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[hokie66]

That new bridge concept is hardly new. There are several existing examples of single sided cable stayed footbridges with real structural stays and real inclined towers. The architectural rendering does look a bit spindly, but hopefully the structural design will sort that out this time.

 

[spsalso]

I don't understand the need for this bridge, or the one that fell down. There is an intersection right there, with stop lights, crosswalks, and walk signals. Are college students challenged by this concept?

Rather than an un-needed bridge, how about tuition rebates? "Say, college student. Would you rather have a bridge, or money in your pocket?"


Does the word "hubris" apply to this project?


spsalso

 

[AusG]

I believe the need such as it is, is to boost the value of an upmarket housing development the university is undertaking on the Sweetwater side of the road. A nice short traffic-free and weatherproof stroll from home to campus, etc, with a flagship structure to put on the brochures. Or at least it was.

 

[LittleInch]

Dik, FIGG took a large hit for it and I suspect are still being sued.

Not sure about other sanctions against the firm or individuals.

https://www.nbcmiami.com/news/local/last-fiu-bridge-defendant-settles-with-three-victims/2177541/

https://panthernow.com/2022/01/31/final-settlement-marks-the-end-of-fiu-bridge-collapse-litigation/

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hokie66]

AusG,
Student housing, sure, but I doubt it is upmarket in Sweetwater.

Dik and LI,
Too bad Figg was not hired to design this scheme instead of the concrete truss fiasco. Cable stayed steel bridges have been their forte.

 

[LittleInch]

I don't understand the need for this bridge, or the one that fell down. There is an intersection right there, with stop lights, crosswalks, and walk signals. Are college students challenged by this concept?

err yes. The might get wet when it rains and they then don't have to look up from their phones / devices when trying to cross an 8 lane highway...

Some also don't recognise green = walk, red = stop.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

Thanks LI... didn't know that.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[spsalso]

I saw a picture of the new bridge design. Imagine, both uninspired and pretentious at the same time.

Wouldn't it be neat if the top of the tower had a giant counterweight suspended from the top? A simple cable pair anchored in the ground would certainly work, but it doesn't have the drama of walking under a multi-ton counterweight.

This being Florida, perhaps the giant concrete counterweight block should be replaced by a giant tank of water. Then students can use it as a pool! You could even have a glass bottom!!!


spsalso

 

[hokie66]

Santiago Calatrava is well known for bridges like this, but always with flair. I think this is inspired by his work, but not inspiring.

 

[AusG]

I thought of the counterweight idea too. A giant pair of steel balls maybe? Then I figured they weren't in the market for gags

 

[LittleInch]

https://en.m.wikipedia.org/wiki/Cantilever_spar_cable-stayed_bridge

And open up the "Of this type" section.

But I agree, this looks like a poor copy.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Tomfh]

Definitely looks like a cheap knock-off of a Calatrava.