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?
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".
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.
In alt.home.repair, on Wed, 15 Aug 2018 11:15:09 -0500, dpb
If you click on the picture, it gets bigger and it looks quite a bit
like other bridges by the same guy:
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.
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.
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