from the shape-of-things^Wbridges-to-come dept.
Arthur T Knackerbracket has found the following story:
Newly identified bridge forms could enable significantly longer bridge spans to be achieved in the future, potentially making a crossing over the Strait of Gibraltar, from the Iberian Peninsula to Morocco, feasible.
[...] A bridge's span is the distance of suspended roadway between towers, with the current world record standing at just under 2km. The most popular form for long spans is the suspension bridge form, as used for the Humber Bridge, though the cable-stayed bridge form, where cables directly connect the tower to the roadway -- such as used in the recently constructed Queensferry Crossing in Scotland -- is becoming increasingly popular.
As bridge spans become longer, a rapidly growing proportion of the structure is needed just to carry the bridge's own weight, rather than the traffic crossing it. This can create a vicious cycle: a relatively small increase in span requires use of significantly more material, leading to a heavier structure that requires yet more material to support it. This also sets a limit on how long a bridge span can be; beyond this limit a bridge simply cannot carry its own weight.
[...] Professor Matthew Gilbert from the University of Sheffield, who led the research, said: "The suspension bridge has been around for hundreds of years and while we've been able to build longer spans through incremental improvements, we've never stopped to look to see if it's actually the best form to use. Our research has shown that more structurally efficient forms do exist, which might open the door to significantly longer bridge spans in the future."
[...] The mathematically optimal designs contain regions which resemble a bicycle wheel, with multiple 'spokes' in place of a single tower. But these would be very difficult to build in practice at large scale. The team therefore replaced these with split towers comprising just two or three 'spokes' as a compromise that retains most of the benefit of the optimal designs, while being a little easier to construct.
For a 5km span, which is likely to be required to build the 14km Strait of Gibraltar crossing, a traditional suspension bridge design would require far more material, making it at least 73 per cent heavier than the optimal design. In contrast, the proposed two- and three-spoke designs would be just 12 and 6 percent heavier, making them potentially much more economical to build.
[...] The team emphasise that their research is just the first step, and that the ideas cannot be developed immediately for construction of a mega span bridge. The current model considers only gravity loads and does not yet consider dynamic forces arising from traffic or wind loading. Further work is also required to address construction and maintenance issues.
-- submitted from IRC
Journal Reference:
Helen E. Fairclough, Matthew Gilbert, Aleksey V. Pichugin, Andy Tyas, Ian Firth. Theoretically optimal forms for very long-span bridges under gravity loading. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science, 2018; 474 (2217): 20170726 DOI: 10.1098/rspa.2017.0726
(Score: -1, Flamebait) by Anonymous Coward on Monday September 24 2018, @06:05AM
Let's face it, SJWs are not useful for anything else.
If you run out of them, use fudgepackers. They will connect to each other via suction.
(Score: 1, Troll) by Anonymous Coward on Monday September 24 2018, @06:40AM (7 children)
We can do this, but we obviously shouldn't. Europe has enough trouble with migrants already. Even the tunnel between France and the UK has been trouble.
(Score: 2, Offtopic) by Nuke on Monday September 24 2018, @07:12PM (6 children)
Why was this modded as spam? You might disagree with it (there is a mod type for that) but it is not spam. As it happens, it's true.
(Score: 0) by Anonymous Coward on Monday September 24 2018, @07:56PM (2 children)
And it is true that it is spam, obviously.
(Score: 0) by Anonymous Coward on Tuesday September 25 2018, @01:23AM (1 child)
Are you confused about the difference between Offtopic and Spam? Because you seem to be.
(Score: 2) by aristarchus on Tuesday September 25 2018, @05:26AM
Comments about the difference between offtopic and spam are indeed spam, when what we are looking for is span. And just because the Powers That Be (ever notice that TMB could be an acronym for The Mighty, um Powers that Be?) have rescinded the spam mod does not mean that it still does not apply! Oh, look! A double negative! Keep Donald and Runaway away from this, lest confusion ensue. But back to the point, it was spam, it was modded as spam, and it is spam, spam, spam, and spam! Bloody Vikings! [youtube.com]
I like Spam, spam, spam, spam, spam, spam, spam, baked beans, and spam! But the baked beans are off.
(Score: 2) by The Mighty Buzzard on Tuesday September 25 2018, @05:29AM (2 children)
Taken care of.
My rights don't end where your fear begins.
(Score: 2) by aristarchus on Tuesday September 25 2018, @06:25AM (1 child)
You bastard! You killed Kenny!
(Score: 2) by The Mighty Buzzard on Tuesday September 25 2018, @01:17PM
Yeah, I hate to mess up a perfectly good bit of textual sparring but it's part of the job.
My rights don't end where your fear begins.
(Score: 5, Interesting) by aristarchus on Monday September 24 2018, @07:30AM (19 children)
A bridge too far. At some point, the cost of the infrastructure outweighs any possible profit deriving therefrom. Works with vertical, where the weight of the cables of an elevator exceed the tensile strength of the cables their own selfs. Thus in tall buildings, you have to transfer mid-height. And Bridges, where the span ceases to bear even itself. But this is more the case in post-modernist capitalism, copyright, and micro-transactions, where the sheer costs of accounting will overbear the profits from keeping track of whom owns what. For example, khallow used to own a backhoe. But now he cannot even afford to rent it out. Of course, he blames "government regulations", but that is not it at all. It is just that he would spend more time and money making sure he was making money than the money he was making. Dead-end capitalism. A bridge too far.
(Score: 3, Insightful) by Gaaark on Monday September 24 2018, @10:11AM (2 children)
That started soooooo well.
Oh well.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2) by DeathMonkey on Monday September 24 2018, @04:59PM (1 child)
I thought it was a pretty funny callback. But hey, comedy is in the eye of the beholder.
(Score: 2) by Gaaark on Monday September 24 2018, @09:28PM
I'm trying to get Ari to post intelligently as well as humorously, instead of always going into alt-right land: he can post really well...and he can do epic fails, too.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1, Informative) by Anonymous Coward on Monday September 24 2018, @11:55AM
https://en.wikipedia.org/wiki/Kone#KONE_UltraRope [wikipedia.org]
(Score: 1, Interesting) by Anonymous Coward on Monday September 24 2018, @02:51PM (12 children)
That's not why you have to transfer elevators. In virtually all buildings you transfer elevators well before the point where the tensile strength and weight of the cabling becomes a problem. An elevator can easily go 70+ floors without issues like that. Most freight elevators will go from the bottom floor to the top floor.
The reason why you have to transfer elevators is typically because things bog down very quickly when you have elevators trying to service too many floors. A typical elevator really only carries at most 10 people, and that includes the ones too far back to easily get out. During times like when people are coming or going from work, it can very easily get all jammed up.
That's why you generally have elevators that sever portions of the building, not because there's a technical limitation on the length of cabling. Only a relatively small number of buildings in the world are tall enough that the elevator cannot be built that's long enough to service the entire building.
Or, as I always say, Aristarchus, you're a fucking moron, go back to your kindergarten class and try not to eat too much paste. Bowel obstructions suck.
(Score: 2, Informative) by aristarchus on Monday September 24 2018, @07:00PM (11 children)
And this is why I always say, AC, that ACs are morons.
Source HERE! [freedoniagroup.com], you totally ignorant AC! Some helpful AC as already mentioned KONE UltraRope. Fascinating. This is what happens when an AC's ignorance and lack of knowledge extends beyond the carrying capacity of the organization necessary to maintain intelligent life.
(Score: 0) by Anonymous Coward on Monday September 24 2018, @07:51PM (4 children)
You are the moron.
https://www.researchgate.net/publication/320474751_The_Design_of_Elevator_Systems_in_High_Rise_Buildings_Part_1 [researchgate.net]
(Score: 2, Insightful) by aristarchus on Monday September 24 2018, @08:01PM (3 children)
No, you are the moron! Why am I shouting at an AC? See what you made me do! Your citation seems to have nothing to do with materials limitations on the engineering questions, only traffic flow, which does not replace the materials question. Did you get educated in America, perchance?
(Score: 1, Insightful) by Anonymous Coward on Tuesday September 25 2018, @12:11AM
Ninnyhammer.
(Score: 1, Funny) by Anonymous Coward on Tuesday September 25 2018, @01:22AM (1 child)
Obviously your elevator doesn't go all the way to the top floor.
(Score: 3, Insightful) by aristarchus on Tuesday September 25 2018, @04:24AM
Archimedes was building elevators [landmarkelevator.com] before your language even existed, you young barbarian! Show some respect!
But more to the point, it seems AC elevators don't go all the way to the ground floor, being based on an indeterminate anonymity that makes it hard to know where you really are at all. So let's stick to the topic, and ponder enlarged bridge spans, and remind ourselves that if you have a enlarged bridge span for more than four hours, you should seek immediate medical attention for your elevator diversion.
And I am amazed/appalled that no one has brought up Wonkavators. Upways, downways, sideways, anyways. No cable limitation there. Good day!
(Score: 0, Informative) by Anonymous Coward on Tuesday September 25 2018, @01:57AM (5 children)
He said 70+ stories, you say a few hundred meters.
It's the same fucking thing, you retard; one story is 4 meters, give or take.
(Score: 0) by Anonymous Coward on Tuesday September 25 2018, @02:50AM
Cable limit is about 500 meters, making it about 125 stories.
(Score: 0, Informative) by Anonymous Coward on Tuesday September 25 2018, @03:05AM (3 children)
And you don't typically see elevators that are that long, except for the freight elevator and perhaps a penthouse elevator by an extremely rich individual who can afford to spend the money on the floor space it takes up. Aristarchus is a moron.
The practical limit on the height of elevators has to do with the number of trips that the elevator is expected to perform; especially during the the peak periods before and after work as well as during lunch time. Yes, it's possible to have a 70+ floor elevator, but it's not practical for anything other than the freight elevator, because in an office building, as few as 15 floors can wind up with a substantial wait when everybody is wanting to use them all at once. An elevator of 70 floors serving passengers would be crippled by the massive number of people using it.
This is the main reason why it is common for highrise buildings have one or more banks of express elevators allowing them to stack local elevators to service individual floors.
Even if you switch to a cableless system, you'd still be limited to a similar number of floors being serviced unless you have a system of elevators that can switch shafts or shift out of the way of each other due to congestion.
(Score: 2, Insightful) by aristarchus on Tuesday September 25 2018, @03:51AM (2 children)
Of course you realize, oh pugnacious AC, that you are involved in a not so subtle program of distraction? Next you will be telling us that it is possible to build a bridge to the top of the tallest building, blithely ignoring that nothing you are saying about elevators is relevant to the point I was making about Bridges Too Far. Nice try. You probably distracted khallow, . . . unless you are khallow! Not arguing in good faith? Checks out.
(Score: 0) by Anonymous Coward on Tuesday September 25 2018, @05:32AM (1 child)
Lose an argument, then suddenly realize the argument was off-topic.
Classic arse-tarchus.
(Score: 2, Insightful) by aristarchus on Tuesday September 25 2018, @06:18AM
Because the argument was off topic. Why do you think I threw in a structural limit to capitalism spin in there, you cretins of the cold war? Do you not realize that your thinking is not only invalid, (that is, your reasoning does not support the conclusions you admire, even if your premises and starting points are true), but your axioms are so far removed from reality that you could buy a Rainbow Bridge, with or without Thor, but probably with Unicorns, and Pedophilic Distributed Defense Unicorns. Snap out of it, you morons. Also, the first part of my name is from the greek, ἄριστος, meaning "the best". Your riff on it suggests certain proclivities. Are you not already over-extended enough? Is not your intellectual capital wasted in the defense of the same? At long last, AC, have you no shame?
(Score: 1, Informative) by Anonymous Coward on Monday September 24 2018, @03:33PM (1 child)
+1 Marxist structural engineering analogy. I like! (After all, is not Marxism the application of mathematical analysis to capitalism itself?)
(Score: 2, Disagree) by The Mighty Buzzard on Tuesday September 25 2018, @05:35AM
Nah, it's just poetic envy.
My rights don't end where your fear begins.
(Score: 4, Interesting) by MostCynical on Monday September 24 2018, @08:05AM (5 children)
if the picture of the proposed bridge in TFA is to scale, the upright components of this brige are over three kilometres tall.
Aeroplanes and helicopters watch out!
Suspect it will have interesting microclimate effects, as well.
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 4, Insightful) by choose another one on Monday September 24 2018, @09:47AM
They look to be about half-span long and 30degrees off vertical, 5km span would give only 2km high - still stupidly high though.
Bigger problem is "not yet consider dynamic forces arising from traffic or wind loading" - because as every engineer knows making bridges lighter is always the right thing to do...
(Score: 2, Interesting) by Anonymous Coward on Monday September 24 2018, @02:56PM (1 child)
This is the sort of thing where tunnels make a lot of sense. For places like this, you'd be better off building a tunnel underneath rather than trying to go over the top. Tunnels are expensive, but the technology needed is mostly there. They could likely even build a tube to put the tunnel in if they don't want to got to the absolute bottom of the body of water.
Around here, we've got a similar sort of problem where we've been using ferries to ferry people across the sound and the cost of tunneling has gotten to the point where the cost of just a couple ferries completely funds the building of a fairly long tunnel that would greatly improve the connection to the peninsula.
(Score: 2) by bob_super on Monday September 24 2018, @06:42PM
Today I learnt that the South end of the Gibraltar strait is actually part of the Eurasian plate.
I was going to point out that a tunnel that has to shrink over 2cm per year would be an interesting feat, but it turns out that it doesn't need to, since both end are indeed on the same plate, not on the Africa Plate.
(Score: 2) by deimtee on Tuesday September 25 2018, @01:34AM (1 child)
Wikipedia says the strait is between 300 and 900 metres deep. If your alternative is to build 3km towers, you may as well drop a couple of shorter ones in the in the middle and have reasonable spans.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 0) by Anonymous Coward on Tuesday September 25 2018, @03:18AM
TBH, probably the easiest way of doing it, would be a floating bridge. It would be a challenge as this is connected to the ocean, and there's plenty of ships that are coming and going, but it would probably be easier to build a floating bridge than a suspension bridge.
The engineering on it would be pretty nifty as you could probably put the road surface on a gymbol and have a high rise section that's high enough to allow for large ships to pass under. Certainly easier to do than try to force a suspension bridge to do it.
(Score: 4, Funny) by suburbanitemediocrity on Monday September 24 2018, @09:25AM (11 children)
And drain the med.
(Score: 2) by choose another one on Monday September 24 2018, @09:51AM
Welcome to Atlantropa...
(Score: 2) by Gaaark on Monday September 24 2018, @10:14AM (2 children)
Don't give the Americans any ideas
"Hey, dey have WMD in that there Gibaltor! Let's drain the fecker and then claim teh oils!"
:)
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2) by suburbanitemediocrity on Monday September 24 2018, @10:34AM (1 child)
It was originally a German idea. I'm sure the Americans know about it by now.
(Score: 2) by Bobs on Monday September 24 2018, @04:30PM
Yes, but keep it quiet: we don’t want Trump to hear about it.
(Score: 2) by zocalo on Monday September 24 2018, @11:52AM (1 child)
UNIX? They're not even circumcised! Savages!
(Score: 0) by Anonymous Coward on Monday September 24 2018, @03:28PM
I dunno, this sounds more like a dike.
(Score: 0) by Anonymous Coward on Monday September 24 2018, @03:16PM (4 children)
Yeah, not having a Mediterranean sea would surely solve the problem of refugees crossing it. ;-)
(Score: 2) by hendrikboom on Monday September 24 2018, @04:34PM (3 children)
Damming Gibraltar completely would end up with the Mediterranean drying up. There's a net inflow of water because of evaporation in the sea.
(Score: 2) by hendrikboom on Monday September 24 2018, @04:34PM (2 children)
But there might be an option for a power generation dam instead of a complete blockage.
(Score: 0) by Anonymous Coward on Monday September 24 2018, @09:53PM (1 child)
And preventing all that evaporation could help stop global warming!
(Score: 0) by Anonymous Coward on Tuesday September 25 2018, @02:15AM
All that water would have to go somewhere. The rest of the worlds oceans would rise.
(Score: 0) by Anonymous Coward on Monday September 24 2018, @01:50PM
pretty cool ... but the upkeep cost?
maybe using more material equals less upkeep? just guessing.
i suppose the problem with long bridges is that it cannot be ONE bridge because of expansion and stuff.
so i suppose the proposed design is acctually multiple bridg(segments) where each could stand on its own.
it just looks like one bridge because all the ends and starts of each segment are really close to each other?
one could also use the design to make a artificial island in the middle of no where by rotating the "road" around the center pilon to get a circle?
anyways, since i am lazy person j would just make short pipe segments (50m) with a diameter of 5 km(lol) and then bury them half in the ocean: --oooooo--
of course the bridge top would be a bit high (and use lots of material) but methinks we can forget about upkeep for the next 1000 years :)