Bridge collapse near Genoa (IT)

Might have some relevance to a few
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Re: Bridge collapse near Genoa (IT)

#21 Post by G-CPTN » Fri Aug 17, 2018 4:26 pm

OFSO wrote:
Fri Aug 17, 2018 4:17 pm
We were supposed to receive transcripts of the proceedings - still waiting today.
I was banned (permanently it seems) from TOP R&N for suggesting (regarding a delayed accident report) that the Italians were renowned for their laid back attitude and no sense of urgency (I quoted 'Domani' as being the predominant oft-quoted phrase).

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Re: Bridge collapse near Genoa (IT)

#22 Post by Capetonian » Fri Aug 17, 2018 4:29 pm

Last year I travelled on some local trains around Milano. I have never seen such filthy dirty trains anywhere else in Europe, broken or torn seats, windows thick with filth, floors covered in rubbish, stinking toilets that you could smell from one end of the coach to the others. The station I had to get off at near Crema looked as if it had been abandoned and they'd started bulldozing it.

I have travelled by train in the old Yugoslavia, Albania and Romania. This was worse.

To make matters worse the stations and trains are full of invaders from the ME and Africa, and the railway staff and police do nothing about them travelling without tickets, whereas I was invariably asked for mine. Italy has lost control.

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Re: Bridge collapse near Genoa (IT)

#23 Post by ian16th » Fri Aug 17, 2018 5:37 pm

An observation from todays Guardian:
In the country of the Coliseum, Roman aqueducts and 1,000-year-old churches, it seems paradoxical that 40-year-old structures are crumbling.
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Re: Bridge collapse near Genoa (IT)

#24 Post by OFSO » Fri Aug 17, 2018 7:50 pm

Odd how the two most friendly peoples in Europe - the Italians and Greeks - have chaotic countries. And the arseholes the most efficient. (Supposedly).

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Re: Bridge collapse near Genoa (IT)

#25 Post by Undried Plum » Sun Aug 19, 2018 1:36 pm

The concrete made by the ancient Romans was incredibly hard wearing, tough and resilient.

Their secret sauce was a volcanic mineral called Pozzolana. It's morphology and chemistry was/is extraordinarily well suited to the formulation of top-quality concrete and had remarkable properties such as actually being strengthened by saltwater and setting well and quickly under fresh water too.

Modern civil engineers are studying its properties and have found that it has a lot of very useful attributes such as being quite 'green' in that it requires a lot less energy and emits much less CO2 in its manufacture.

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Re: Bridge collapse near Genoa (IT)

#26 Post by G-CPTN » Sun Aug 19, 2018 1:45 pm

Undried Plum wrote:
Sun Aug 19, 2018 1:36 pm
The concrete made by the ancient Romans was incredibly hard wearing, tough and resilient.

Their secret sauce was a volcanic mineral called Pozzolana. It's morphology and chemistry was/is extraordinarily well suited to the formulation of top-quality concrete and had remarkable properties such as actually being strengthened by saltwater and setting well and quickly under fresh water too.
What would the Romans in Britain have used in place of Pozzolana?
I cannot imagine that they carted the stuff all the way from Italy.

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Re: Bridge collapse near Genoa (IT)

#27 Post by ian16th » Sun Aug 19, 2018 1:51 pm

G-CPTN wrote:
Sun Aug 19, 2018 1:45 pm
I cannot imagine that they carted the stuff all the way from Italy.
Of course not.

They would have their slaves carry it!

The slave trade was NOT invented for American cotton plantations.
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Re: Bridge collapse near Genoa (IT)

#28 Post by OFSO » Sun Aug 19, 2018 6:25 pm

My German friends just got back after venturing far afield. They drove over the Genova bridge a couple of months ago; said it felt shaky. Wonder what form of bridge will be errected in its place.

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Re: Bridge collapse near Genoa (IT)

#29 Post by 603DX » Mon Aug 20, 2018 8:44 am

The subject of Roman concrete and Pozzolana was discussed in "The secret of ancient Roman concrete discovered" thread, in the "Non-Aviation Things of General and Historical Interest" section of this forum. Worth another look now.

And post #3 in that 2016 thread, by Capetonian, is eerily prescient of the Genoa collapse!

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Re: Bridge collapse near Genoa (IT)

#30 Post by Capetonian » Mon Aug 20, 2018 9:24 am

Here's that post, which I wrote after we'd driven over that bridge to spend a few days in Florence :
Strange that modern Italy is now a chaotic disorganised mess where nothings works properly. The outskirts of Florence are reminiscent of, if not worse than, those of some Soviet era cities.
The motorway interchanges around Genoa are like something a 12 year old might have made from an old Meccano set.

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Re: Bridge collapse near Genoa (IT)

#31 Post by 603DX » Mon Aug 20, 2018 10:04 am

It will be a while before the true reasons for the collapse emerge, but this link covers distinctive features of the structural designs prepared by Riccardo Morandi.

https://en.wikipedia.org/wiki/Riccardo_Morandi

I note that instead of using steel cable stays protected from corrosion by surrounding them with some form of heavy duty plastic sheathing, which is common practice nowadays, he chose to enclose them in concrete. This is described in the text as "prestressed concrete". Steel cables under high tension tend to stretch slightly over the years, termed "creep", and this is usually taken into account when designing any prestressed concrete structure, by initially installing a marginally higher tension in them. If this is either not done, or if insufficient allowance is made for the amount of expected creep extension in service, then the surrounding concrete can crack, being weak in tension. If this occurs, rain penetration can cause hidden corrosion of the vital cables inside. The result might be eventual tensile failure of a critical supporting stay. One of a number of potential failure modes of that rather unconventional bridge design. Time will tell ...

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Re: Bridge collapse near Genoa (IT)

#32 Post by 603DX » Mon Aug 20, 2018 1:59 pm

One of many interesting features of the collapsed cable-stayed section of the bridge is that the minimum number of supporting stay cables is used. Each sloping stay is a structurally critical member, with no "fail-safe" provision. The vast majority of cable-stayed bridges worldwide have multiple stays, attached at intervals along the spans, and looking like a fully strung harp. This means that if any one stay cable snaps for any reason, the bridge still holds together, and the broken one can simply be replaced with a new one. This would not be possible on the Genoa bridge, and complete tensile failure of one of the stays could lead to complete collapse of the whole structure like a house of cards, aided by the fact that the short lengths of bridge deck are "simply supported" spans with no bending continuity. This feature is clearly shown in the many photographs of the exposed ends of the deck, which show no signs of concrete fracture or tangled mass of reinforcing bars, because they are neat shelf supports for the deck bearings.

This doesn't mean that it's proof that a single stay failed first, triggering the complete failure of the concrete tower's columns and the deck together. Other collapse sequences might have taken place. The rather odd looking reinforced concrete tower structure itself might have failed, bringing the same end result, or its massive-looking foundation plinth might have suddenly settled due to a failure of ground conditions at that point, again leading to the same final appearance. Some reports speak of maintenance work in progress on the collapsed tower and its base. The answers will probably be found from a combination of large-scale forensic science, eyewitness statements, videos, and so on.

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Re: Bridge collapse near Genoa (IT)

#33 Post by 603DX » Thu Aug 23, 2018 12:14 pm

I received today my copy of "New Civil Engineer", the magazine of the Institution of Civil Engineers, which contains a 5 page special report on the Morandi Bridge collapse. It is obviously too early in the aftermath investigations to make any firm conclusions, but a number of very interesting findings have emerged so far. (Especially if compared with my two posts above.)

The investigators have found damage and corrosion to the main stay cables on the fallen section of the bridge. "Sources close to the investigation" have said that failure of the cables - which were encased in concrete to protect them from the elements - may be behind the collapse. "I have heard that video footage from the CCTV cameras on the bridge showed concrete being exploded off the main stay because of the violence of some of the cables snapping underneath", one investigation source said. A former editor of the magazine said "It looks like the structure has collapsed around the foundations, rather than the foundations causing the collapse. I suspect that one of the supports from underneath has given way. That or the cables above have suffered from corrosion". A past president of the Institution of Structural Engineers agreed that corrosion of the cables was a likely cause of collapse.

Tender documents seen by New Civil Engineer reveal that the section of the bridge which collapsed was set for significant repairs along with the adjacent tower and stay cables. The main stay cables on both sections were scheduled to be beefed up with new steel cables strapped to the surface of the existing concrete and attached to the deck and apex of the pylon with new steel anchor blocks. The works echo similar repairs carried out on the third tower, closest to the land, in the 1990s. This work is clearly visible on photographs of the bridge following its collapse.

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Re: Bridge collapse near Genoa (IT)

#34 Post by OFSO » Sun Sep 23, 2018 7:49 am

Blasted media, we'll never hear another word about it. Clearing the site, demolishing the other towers, plans and designs for a replacement, all very interesting to those of us who used the bridge, and nothing being reported. Not 'news' any more, is it.

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Re: Bridge collapse near Genoa (IT)

#35 Post by Fox3WheresMyBanana » Sun Sep 23, 2018 11:58 am

Well, until the next one.

There will be a next one, probably within a year.

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Re: Bridge collapse near Genoa (IT)

#36 Post by OFSO » Mon Sep 24, 2018 1:54 pm

Indeed, more brow-beating, more cries of "why, oh why ?" and "who could have foreseen it ?" followed by "lessons have been learned" and then bugger-all until the next one.

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Re: Bridge collapse near Genoa (IT)

#37 Post by Capetonian » Tue Dec 18, 2018 9:33 pm

I am somewhat concerned at the fact that this project is destined for completion in 12 months:

Genoa bridge: Renzo Piano to lead new construction - http://www.bbc.co.uk/news/world-europe-46611314

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Re: Bridge collapse near Genoa (IT)

#38 Post by G-CPTN » Tue Dec 18, 2018 10:36 pm

Have you seen this? :-

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Re: Bridge collapse near Genoa (IT)

#39 Post by 603DX » Wed Dec 19, 2018 3:55 pm

Capetonian wrote:
Tue Dec 18, 2018 9:33 pm
I am somewhat concerned at the fact that this project is destined for completion in 12 months:

Genoa bridge: Renzo Piano to lead new construction - http://www.bbc.co.uk/news/world-europe-46611314
I share your concern Cape, but don't consider it remotely linked to reality. I fear that Italian Braggadocio is at the root of such ludicrous statements. "Completion in 12 months" and "a new bridge to last 1,000 years" are in my view neither rational nor compatible assertions, as reactions to the utter humiliation of the collapse tragedy. The source of such announcements is the commission set up to reconstruct the bridge, headed by Marco Bucci, who is also the mayor of Genoa.

Up to 20 possible designs for a replacement bridge are reported to have been under consideration, including proposals by the architect Renzo Piano and the architect/engineer Santiago Calatrava, who is a fully qualified bridge engineer and architect. Renzo Piano is primarily a building architect, who needs 100% support by an experienced firm of structural engineers with special knowledge of bridges, which he does have the grace to admit. Calatrava, who visited our offices when I was still working with British engineering consultants, is a very competent bridge designer with many sound structures to his credit.

It has been estimated by others that it would take at least 18 months to erect an adjacent, temporary bridge (possibly of the steel Bailey/Mabey modular type), at a cost of about £45 million, to buy time for a new permanent bridge to be designed and constructed on the original alignment, with full provision for continuous and effective inspection and maintenance during its service life, which would be at least 120 years. It could take about 5 or 6 years to realistically achieve that. In my opinion the new permanent structural design should be fully independently checked by another firm of civil engineers, for structural adequacy and maintenance inspection provisions. That is what is always done for major new bridges in the UK nowadays, such as the Mersey Gateway and Queensferry bridges, and by its abysmal performance in Genoa, was presumably not done for the partially collapsed Morandi structure.

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Re: Bridge collapse near Genoa (IT)

#40 Post by ian16th » Wed Dec 19, 2018 4:04 pm

I bet Cleveland Bridge & Engineering weren't asked to quote!
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