raymundo:
whisperingsmith:
295m long and often nose to tail with Artics on it going to the Middle East.Where there many artics about in the 16th century ■■
teehee 
malcolmgbell:
Carryfast:
muckles:
In fact it appears that bridges need maintenance, especially when they get older and have spent many years in a hostile environment taking far more traffic than the designers could have imagined.Who’d have thought hey!
Firstly the stress flaws in the cable stayed design are obvious ( continuous rocking,tensile/lateral loads applied to towers and decks unlike suspension bridge design for one example ) also the critical nature of cable stressed concrete as opposed to reinforced concrete.
While it’s obvious that stainless steel is an important solution to the corrosion issue which was ignored when many bridges were built because of cost.
They talk of structural steel not reinforcing concrete
Re bar is a type of ‘structural steel’.No surprise you seem to have conveniently ignored the post with the other link advertising stainless steel re bar supplies,including the references regarding its superiority over steel.All of which was available in the early 1960’s.Instead of which Morandi chose the worst possible method of suspending a bridge combined with the worst possible method of producing structural concrete ( stressed not reinforced ).As I said even the videos look suspiciously like the tower and the road deck collapsed first before the stay let go.No surprise that the establishment would want to cover that up.
Carryfast:
How does stainless steel discharge ‘rust’.What bleedin rust that’s why it’s stainless steel
They are talking about weathering steel ie coten steel
Weathering steel, often referred to by the genericized trademark COR-TEN steel and sometimes written without the hyphen as corten steel, is a group of steel alloys which were developed to eliminate the need for painting, and form a stable rust-like appearance after several years’ exposure to weather
There’s an hour long programme all about it tomorrow (wednesday) at 9pm on national geographic channel.
Has be better than anything the BBC do
Carryfast wrote:
To be fair if Morandi had taken my advice to use the NY Queensboro design,or even make it a suspension bridge with stainless steel re bar reinforced concrete towers,it would still be standing.But what would I know about designing bridges especially almost 60 years ago.
you should not use stainless steel.it is susceptible to stress corrosion cracking when the temperature is over 140°F (60°C) and chloride solutions are in contact with the steel material. Embedded natural-weathering steels generally do not perform well in concrete containing moisture and chloride. Weathering steels adjoining concrete may discharge rust and cause staining of concrete surfaces.
How does stainless steel discharge ‘rust’.What bleedin rust that’s why it’s stainless steel.Also when did/does the temperature ever reach over 60 C in Genoa.
stainless-uk.co.uk/products/rebar/
It’s also clear that not only did corroding steel contribute to the issues,stressed concrete ain’t the same thing as reinforced concrete.
Simply put, it is concrete formed under stress
Reinforcement Bars are placed in a form and stressed by the stretching of the bars at each end, inducing tension in the bar
Been over it a few times myself…ten lorry drivers killed, off to work for the day, never in a million years would you expect that, poor blokes.
Carryfast:
switchlogic:
Carryfast:
To be fair if Morandi had taken my advice to use the NY Queensboro design,or even make it a suspension bridge with stainless steel re bar reinforced concrete towers,it would still be standing.But what would I know about designing bridges especially almost 60 years ago.Annnnnd we’re off! You were a civil engineering advisor at the time? Impressive
You obviously missed the intended irony and sarcasm meant in the reference to almost 60 years ago.Bearing in mind that the Queensboro design at least goes back to 1909 and it’s still standing.How difficult would it have been for Morandi to have said that’s what we’ll use for ours.No need for my help.
To be fair I think only one of us missed the sarcasm 
malcolmgbell:
Carryfast wrote:It’s also clear that not only did corroding steel contribute to the issues,stressed concrete ain’t the same thing as reinforced concrete.
Simply put, it is concrete formed under stress
Reinforcement Bars are placed in a form and stressed by the stretching of the bars at each end, inducing tension in the bar
To be more precise non reinforcement bars ( if not actually cables not bars ) are used to just ‘stress’ the concrete as you describe in the hope of that providing the required tensile strength.‘Instead of’ ‘re bar’ being used to ‘reinforce’ it using the bars themselves to provide the tensile strength.
So the bars/cables lose their pre tension for whatever reason you’re effectively then left what you started with in the form of non reinforced concrete.Bearing in mind that they are weaker than re bar in only being meant to stress the concrete.
On that note feel free to explain why the Milau Viaduct uses reinforced concrete,seemingly using stainless steel re bar going by the description of chrome alloy steel,in addition to limited stressing.
It rests on 7 concrete piers. These support an 11m deep continuous hollow steel deck suspended from 7 steel pylons. The pylons are 87m above deck level and support 11 cable stays on each side.
The 7 piers are rooted in 4 reinforced concrete shafts. Project engineers sunk these deep into the valley bedrock and covered them with more reinforced concrete.
The hollow steel deck was prefabricated in box sections
malcolmgbell:
It rests on 7 concrete piers. These support an 11m deep continuous hollow steel deck suspended from 7 steel pylons. The pylons are 87m above deck level and support 11 cable stays on each side.The 7 piers are rooted in 4 reinforced concrete shafts. Project engineers sunk these deep into the valley bedrock and covered them with more reinforced concrete.
The hollow steel deck was prefabricated in box sections
Notwithstanding the obvious flaws in the type of stresses applied to the towers of a ‘stayed’ bridge v suspension or cantilever.IE It’s obvious that the towers of the design are over stressed by lateral tensile forces even before any real load is applied to it let alone after.
youtube.com/watch?v=QSU8GozlAKc
It also says ‘the towers’ are constructed using reinforced concrete.As opposed to the ‘stressed concrete’ as you described ?,which ain’t the same thing,used in the Morandi lash up.Not to mention seemingly no hollow steel sections used for the Morandi’s road deck.
It’s clear in this case that the NY Queensboro bridge design was the obvious solution for the Polcevera.While if Morandi was the supposed genius he was meant to be going all in for a decent suspension bridge design would also have worked with either still standing unlike what was chosen.
It also says ‘the towers’ are constructed using reinforced concrete.As opposed to the 'stressed concrete why would you use stressed concrete in a vertical structure when the load is being directed down,as opposed to horizontal which tensions the load in a vertical direction
malcolmgbell:
It also says ‘the towers’ are constructed using reinforced concrete.As opposed to the 'stressed concrete why would you use stressed concrete in a vertical structure when the load is being directed down,as opposed to horizontal which tensions the load in a vertical direction
Firstly concrete is strong under compressive loads but it’s useless under tensile loads.Which is why they use re bar to reinforce it to provide the required tensile strength.Stressed concrete is obviously a cheaper but arguably less effective way of providing the required tensile strength.
Ironically the towers of a suspension bridge are mostly under compressive load with the tensile loads on the cables being transferred to the anchor blocks at either end.
While a stayed bridge obviously transmits all of those tensile loads in the suspension cables into the towers also bearing in mind the force x distance equation added to that.
So why would anyone want to use a less effective way of providing the required tensile strength to the towers in the case of a stayed bridge.IE the towers of a stayed bridge need to be able to withstand massive lateral tensile forces continuously pulling them one way and the other.As opposed to those of a suspension bridge mainly putting them under compression.Which leaves the question of the difference in the design of the towers of the Millau v Morandi’s lash up.Also bearing in mind the recent example of the collapse of the Columbian example shown before it was even completed and subjected to any load at all.