OT: Genoa Bridge Collapse and construction

https://www.nytimes.com/2018/08/15/world/europe/italy-genoa-bridge-collapse.html
Look at how this bridge was constructed. They used concrete for the stays that hold it up. I don't see how concrete would ever be used for that, since concrete has poor tensile strength??? IDK where it failed, if that was the cause, but isn't it bizarre?
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Some stunning pictures there:
https://www.aljazeera.com/news/2018/08/dead-italy-bridge-collapse-180814110732151.html
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On 8/15/2018 10:59 AM, trader_4 wrote:

But the whole trestle tower is gone, not just dropped the span owing to a stays failure...that possibly could have been the instigating event but I'd take a guess will be found not to have been...
--




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On Wednesday, August 15, 2018 at 12:15:19 PM UTC-4, dpb wrote:

I guess those concrete stays must actually have cables embedded inside? Seems like a bad design, because then you can't see, inspect for corrosion. Looks like a lot of finger pointing already going on in Italy, with their populist govt faction that's in control getting most of it. Apparently they were ridiculing reports of the serious problems and potential collapse of the bridge as fairy tales. Sounds like their populist version of "fake news".
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On 8/15/2018 11:32 AM, trader_4 wrote:

...
Yes, "prestressed" concrete is either pre- or post-tensioned but there are steel "tendons" with secured end pieces that place the concrete between them in compression. The actual tension loads would have been carried by attachment to those, not transferred to the concrete itself.
If post-tensioned, there are ducts around the tendons and the concrete doesn't contact them; the concrete is poured and cured, then the tendons inserted, tensioned and endplates secured, then tension released.
In pre-tensioned, the tendons are stretched to something like 70% of ultimate yield, the concrete is poured and when cured to strength the tension on the tendons released clamping the concrete between to apply the compressive loading.
I agree I don't see any reason for choosing the technique for the stays, however; sounds like somebody trying to be excessively clever or an architectural whim to produce a visual image that was attempted to be executed despite the drawbacks.
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On 8/15/2018 12:15 PM, dpb wrote:

Maybe they used the same clowns as the Florida International University pedestrian bridge? Or maybe they wanted it on the same angle as the Leaning Tower of Pizza and it WOPped over?
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On 8/15/18 12:15 PM, dpb wrote:

Probably designed by moonlighting FIAT engineers- rather than descendants of the Romans who designed and built the Aqueducts and the Coliseum...
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On 8/15/2018 1:01 PM, Wade Garrett wrote:

OMG :)
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In alt.home.repair, on Wed, 15 Aug 2018 11:15:09 -0500, dpb

https://en.wikipedia.org/wiki/Ponte_Morandi If you click on the picture, it gets bigger and it looks quite a bit like other bridges by the same guy:
https://en.wikipedia.org/wiki/Riccardo_Morandi
which I presume are still standing. "Riccardo Morandi (1 September 1902 – 25 December 1989) was an Italian civil engineer best known for his innovative use of reinforced concrete. Amongst his best known works were the General Rafael Urdaneta Bridge in Venezuela, an 8 km crossing of Lake Maracaibo incorporating seven cable-stayed bridge spans with unusual piers, and the Subterranean Automobile Showroom in Turin. "
I drove by the Turin exit, and we thought we had to be back by Monday morning, so probably wouldn't have had time to go to the Subterranean Automobile Showroom anyhow, but as interesting as it sounds, I'd never heard of it until just now. I can't tell if it's really a showroom or just a parking garage.
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trader_4 posted for all of us...

No.
But the adjoining stay is then in compression, which concrete likes. Don't know what they were doing during the maintenance. Could also be pre-stressed or post-stressed concrete. I also heard that lightning struck immediately prior to it's failure. We still don't have an answer to the Florida? college bridge that fell.
--
Tekkie

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On Wednesday, August 15, 2018 at 3:50:20 PM UTC-4, Tekkie® wrote:

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How can it be in compression when it's going from a tower, down to hold up the bridge deck? There must be cable or steel inside that is under tension.
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