Bridge Collapse in Genoa, Italy 26

[thebard3]

https://www.cbsnews.com/news/italy-...noa-traps-cars-under-rubble-today-2018-08-14/

An interesting theory from the article: "Italian news agency ANSA said authorities suspected that a structural weakness caused the collapse".

Brad Waybright

It's all okay as long as it's okay.

 

[chris snyder]

RandomTaskkk: "Cable snaps in one or other of the right hand stays (perhaps closest, hard to say?)"
Yeah.. it happens so fast..

I can't single step the video, but kept clicking back to 00:37 from 00:38, and it looks like a truck/bus passes by the "closer" right side stay, then there's an almost imperceptible movement in the stay/deck - not sure if it's happening on the "farther" right side.. maybe the stay moves, I can't see deck move. At ~00:39 the cross-piece breaks in middle, then everything comes down - can't see the top of the tower, but I'd think it'd get pulled to the "farther" side.

I wondered how bad the east end was before they stabilized it, and how they determined the condition with cables embedded in concrete. Seen in Vikko's post above 17 Aug 18 17:25, the center tower had plates at the top, the west (failed) had nothing, and the east end looks "super supported" and expensive (I'm not structural but looks much stronger than what could be within concrete stays).

 

[thebard3]

Pre-collapse deformations noted from space borne synthetic aperture radar.

https://www.mdpi.com/2072-4292/11/12/1403

These look like significant changes to me that should probably have been detected during inspections.

Brad Waybright

It's all okay as long as it's okay.

 

[charliealphabravo]

Amazing.

 

[JAE]

Here's a conclusion in the pdf report:

[red]Overall this study shows that either CSK and SNT InSAR measurements are now accurate enough
to measure millimeter scale deformation processes, providing information, that can help mitigate
deformation-related hazards to large-scale infrastructure.[/red]


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[JAE]

The video on the link was interesting:

https://www.mdpi.com/video_load/20307f469752d536340ed8223be3c7b1/mp4

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[Pete_K]

NOVA covered this collapse in a show on 10/27. I haven't had a chance to watch yet, did anyone else?

 

[thebard3]

Pete,
I watched that episode and fell asleep at the exact time they pointed out the probable failure. I did catch that they apparently believe that voids in grout around the cables allowed enough water intrusion to cause significant corrosion of the cables. Not particularly surprising, I think.

Brad Waybright

It's all okay as long as it's okay.

 

[charliealphabravo]

I wonder how they happened to have the SAR data for this bridge, and the availability for any given structure in the world.

 

[stevenal]

I DVRed the NOVA program it and watched it last night. Had to rewind a bit when they showed a bridge I drive over about once a week. Audio at the time was speaking of "structurally deficient" bridges.

 

[BridgeSmith]

Structurally deficient can mean a number of different things, none of which indicate there is any known danger of it falling down.

Rod Smith, P.E., The artist formerly known as HotRod10