Da Vinci Bridge Design Holds Up Even After 500 Years, MIT Proves (cnet.com) 79
Researchers at MIT have proven that Leonardo da Vinci knew what he was doing when he came up with a novel bridge design that would connect Istanbul with its neighbor city Galata. At the time, it would've been the world's longest bridge, with an unprecedented single span of 790 feet -- constructed without wood planks or even mortar joints. But, unfortunately, it was only recently put to the test since the design was rejected by Sultan Bayezid II in 1502 A.D. CNET reports: "It was time-consuming, but 3D printing allowed us to accurately recreate this very complex geometry," MIT graduate student Karly Bast said in a release on Thursday. Bast worked with a team of engineering academics to finally bring to life a faithful 1-to-500 scale model of da Vinci's famously rejected bridge design, putting the Renaissance man's long-questioned geometry to the test by slicing the complex shapes into 126 individual blocks, then assembling them with only the force of gravity. The group, which presented its work this week in Barcelona, relied on the sketches and descriptions found in da Vinci's letter bidding for the job, along with their own analysis of the era's construction methods.
The structure is held together only by compression -- the MIT team wanted to show that the forces were all being transferred within the structure, said Bast. "When we put it in, we had to squeeze it in." Bast said she had her doubts, but when she put the keystone in, she realized it was going to work. When the group took the scaffolding out, the bridge stayed up. "It's the power of geometry," she said.
The structure is held together only by compression -- the MIT team wanted to show that the forces were all being transferred within the structure, said Bast. "When we put it in, we had to squeeze it in." Bast said she had her doubts, but when she put the keystone in, she realized it was going to work. When the group took the scaffolding out, the bridge stayed up. "It's the power of geometry," she said.
Re:Scale? (Score:5, Insightful)
The point of a bridge is to also allow things to pass under. Scaffolding may have been in the way (and an eye sore).
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Re:Scale? (Score:5, Interesting)
The original 790 feet converted to 1:500 scale [wikipedia.org] model means it is 790 / 500 = 1 foot ~7 inches. 3D printing would have to be precise for that tiny size.
But yeah, it would have been nice to a bigger model at 1:10 scale such as 79 feet for the modal.
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The model is approx 32". I make that as approximately 1:350, but even the MIT article says 1 in 500.
[1] http://news.mit.edu/2019/leona... [mit.edu]
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Obviously a meter is slightly longer than 39". 280m is actually 917' 7".
Span != length (Score:2)
Keep in mind that the span and length are two different numbers.
The span is measured between the point where the arch underneath meets the ground
The length is measured between the furthest extents of the bridge structure (measured parallel to the span direction)
In this case the massive thickness of the bridge at it's feet adds a large fraction of the span in additional length.
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Which is not a number that any of the articles mentioned. A much bigger number.
Did you even do the math?
Re:Scale? (Score:5, Informative)
So it was inspired by Da Vinci.
Re:Scale? (Score:5, Insightful)
The original 790 feet ... But yeah, it would have been nice to a bigger model at 1:10 scale such as 79 feet for the modal.
A 79 foot long model would have been cost prohibitive for a grad project. But a 1:100 scale so you get a bridge ~8 feet long should have been easily doable and that would have been big enough for a person to walk on, roll carts across, or whatever to see how to really held up to bearing weight; or see if the incline was usable in a practical way; etc.
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Agreed, a ~8 foot long model would be interesting to see.
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10x big is 100X as strong, 1000x heavy (Score:3)
Picture a structural member 1 meter by 1 meter by 10 meter, made of some strong material. That's 10 cubic meters of strong material.
If we make it "ten times bigger", it becomes 10 meters by 10 meters 100 meters. That's 10,000 cubic meters. "Ten times as big" is one thousand times as much material. The cross section, and therefore tensile strength, is 100x. So in terms of tensile strength, scaling up 10x makes it 100x as strong.
(Where "strong" means load carrying capacity, NOT the stress or modulus - we
Ps - defects increase with size (Score:2)
I forgot to mention that all assumes perfect material. .0001. Scaled up 10x, it's 1,000 more material - and 1,000 as many opportunities for defects in that material.
A sample of size 1x1x1 has some probability of having voids or defects of size
Re: Scale? (Score:2)
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Sure, but 280 meters is an awfully long span.
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This bridge is in Ronda, Andalucia, Spain: https://www.trover.com/d/1evcC... [trover.com]
Not middle age, but still mind boggeling: https://en.wikipedia.org/wiki/... [wikipedia.org]
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As I read this, I can practically hear these same cowardly excuses coming from Sultan Bayezid II's stonemasons. Waaaah, this design is too complicated!
Clearly, some things never change.
Re: Scale? (Score:5, Funny)
So, they started with the bridge and ended up delivering a hashish pipe.
Funny. If I had mod points (Score:2)
That was funny
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Re:Scale? (Score:5, Insightful)
Just because it works on a scale model doesnt mean it would work in real life. For one the construction methods of the time may not have allowed creation of precise shapes that 3D printing have allowed.
So you are FUDing without any knowledge of the subject? Well this is Slashdot.
It has been common practice to make very precise shapes out of stone for a few thousand years. You may have seen a few ancient statues, which exhibit exactly this skill, then there are to precisely flush fitted stone blocks at Sacsayhuaman [wordpress.com] as just one example. Making precise polygonal blocks was not challenging even in ancient times. They could measure angles as fine as the eye could see, and grind surfaces perfectly flat.
Also may have been cost prohibitive to build the necessary scaffolding at that scale. If you are going to build that much scaffolding might as well leave the scaffolding up and run a road on top.
That's why nobody ever built bridges out of stone, since the wood scaffolding was just fine?
This argument applies to any bridge or arch structure - if it were valid. But wood scaffolding is not durable, it deteriorates exposed to the elements in decades, and requires continual maintenance, and scaffolding is amazingly enough - often not a bridge - it needs only to hold the stone blocks in place for a short time and does not need to consider long term stability, Also for very large stone arches there are a number of construction tricks so that the scaffolding never has to hold up the whole bridge. Looking at the diagrams the MIT group prepared [livescience.com] it looks like the bridge design was built up in two layers. The bottom layer, when complete would be self-supporting and allow the upper layer, and the additional side members to be added.
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you are FUDing without any knowledge of the subject? Well this is Slashdot
No, this is not exclusive to "slashdot". It happens everywhere, except here trollers voice is turned down thanks to moderation.
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A quick GIS of "roman aqueducts" would inform the doubters and the sceptics of what can be done without 3D printing, and modern tools, analysis, and simulations.
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A quick GIS of "roman aqueducts" would inform the doubters and the sceptics of what can be done without 3D printing, and modern tools, analysis, and simulations.
Not to mention cathedrals and churches.
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A quick GIS of "roman aqueducts" would inform the doubters and the sceptics of what can be done without 3D printing, and modern tools, analysis, and simulations.
Not to mention cathedrals and churches.
What a quick GIS won't show you is all the cathedrals and bridges that collapsed.
There are many, eg.:
https://en.wikipedia.org/wiki/... [wikipedia.org]
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And that's not even taking into account other disaster reasons.
Just by skimming over the list I recognized a handful where I know the design was apt and held.
However the underground didn't hold, or there was an earthquake (in an area where none where expected, ever), or there was a fire (maybe even in wartime so maybe other stuff was going on).
Also, what maybe was missed by the poster of the "all the cathedrals and bridges that collapsed" link: the article was especially about a design that oh wonder, seems
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Very valid point (Score:4, Insightful)
So you are FUDing without any knowledge of the subject?
No, he is making a very valid point for which there are plenty of examples. One of the most recent being London's Millennium footbridge which despite detailed calculations and models failed due to insufficient damping. Failures like this are now rare but the reason they are rare is that engineers do detailed calculations and simulations of the full-scale structure to ensure material tolerances are not exceeded and the bridge can cope with wind, floods, people walking, vehicle traffic etc.
For example, when scaled up by 500 times the mass of the structure will increase 125 million times (500^3) or even more if you build it from a denser material like rock. Is there a rock strong enough to withstand these hugely increase stresses while also supporting traffic and resisting winds? Without some detailed calculations to check we simply don't know. It's certainly fascinating to see a bridge design tested at scale after so long and the fact that the scale model works is certainly encouraging but to claim the design will now work just because of a scale model is incredibly premature.....but I hope someone will now go that extra mile since it would be great to see the bridge in full-size assuming it really does work.
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One of the most recent being London's Millennium footbridge which despite detailed calculations and models failed due to insufficient damping
The thing about comparing recent to ancient is a vastly different scope in design. Modern construction is largely based on architects thinking the entire world can be suspended on invisible skyhooks, and engineers which attempt to make do while working out a design to incredibly tight tolerances.
Ever wonder why a modern house falls over when the wind blows a bit too hard but ancient castle walls are still standing? Same principles are being applied here, no one was proposing building a steel suspension brid
Unfair comparison (Score:3)
Ever wonder why a modern house falls over when the wind blows a bit too hard but ancient castle walls are still standing?
Ever wonder how many castle walls fell over during or shortly after construction because the architect was playing it by ear and could not do detailed calculations? The only ancient structures we see today are ones that were strong enough to last several centuries. If you want to do a fair comparison you need to compare the fraction of medieval houses that failed due to wind within the first decade or two after construction and, were you able to do so, I strongly suspect that modern housing will look astou
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The thing about comparing recent to ancient is a vastly different scope in design. Modern construction is largely based on architects thinking the entire world can be suspended on invisible skyhooks, and engineers which attempt to make do while working out a design to incredibly tight tolerances.
Ancient engineers were missing two things: strong materials which could be used in tension like steel and the math to make use of them. Stone structures used in compression are much easier to test because the compression strength of stone is so high that models can simply be scaled up. The only place where they get into trouble, and some middle age churches made this mistake, is with long narrow stone columns which fail in buckling. Salisbury Cathedral has a hair raising example where this almost happene
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For example, when scaled up by 500 times the mass of the structure will increase 125 million times (500^3) or even more if you build it from a denser material like rock. Is there a rock strong enough to withstand these hugely increase stresses while also supporting traffic and resisting winds? Without some detailed calculations to check we simply don't know. It's certainly fascinating to see a bridge design tested at scale after so long and the fact that the scale model works is certainly encouraging but to claim the design will now work just because of a scale model is incredibly premature.....but I hope someone will now go that extra mile since it would be great to see the bridge in full-size assuming it really does work.
Stone is very strong in compression which is why scaling up compression structures made with stone works so well and why ancient engineers were able to build such large structures with it. A model could be made to test for failure and then scaled up without problems. Efficiency is terrible but that is why stone structures survive for so long.
Before the strength of the stone became an issue, the foundation at the ends would fail which is why you find compression dams anchored into bedrock.
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"For one the construction methods of the time may not have allowed creation of precise shapes that 3D printing have allowed."
Sculptors of the time worked to a higher degree of precision than all but the best stonemasons.
DaVinci was a brilliant sculptor
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Sure, and relying on precision sculpting is fine if you're building a 1 meter long model, but doing the same thing 263 meters long is entirely a different story. Such a design would require many craftsman (most of them considerably less skilled then Da Vinci), and all of the blocks would have to be fairly precisely and carefully made or you risk the entire bridge collapsing. The bridge maybe could have been built in theory, but in practice it would have likely been either very expensive and/or too unstable
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Also, medieval (and later) good stonemasons could achieve VERY high quality considering the tools the used.
See Duomo di Milano (Milan, Italy), Kölner Dom (Cologne, Germany), Notre Dame (Paris, yes it broke down some time ago but the design expected it to break down after fire to the roof) and... countless other examples starting with the Roman Empire and ending 19 century.
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Hmm, you obviously don't get it. Look at the precision in the pyramids, built thousands of years ago. The Romans perfromed similar feats 1500+ years earlier.
This would have worked in stone, it just would have required some massive precisely cut stone blocks.
If this had been built, all going well it would probably still be around.
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The biggest threat to this bridge would be the ends moving apart, which they would be under constant pressure to do, the foundations would need to be engineering marvels in themselves for their time.
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The biggest threat to this bridge would be the ends moving apart, which they would be under constant pressure to do, the foundations would need to be engineering marvels in themselves for their time.
I wonder if he was aware of this since the ends of the arch spread so much. The solution is to extend the arch into the ground until the foundation hits rock. Pilings are used under heavy buildings to do this.
Re:Scale? (Score:5, Informative)
Looks like I am late to the party, plenty of other people have already corrected these comments. But, I will add another set.
Just because it works on a scale model doesn't mean it would work in real life.
The whole history of architecture has depended on models and drawings to plan and engineer the real structure, and then the real structures stand for centuries or millennia. That's what models are all about, to plan the real thing that stands.
For one the construction methods of the time may not have allowed creation of precise shapes that 3D printing have allowed.
Lots of examples already given about precision masonry, even in ancient post-neolithic but pre-bronze and pre-iron civilizations. Other examples of grand scale stone masonry that is precision fit and self-supporting: the temples at Luxor and Karnak, the Parthenon, Roman basilicas, Gothic cathedrals.
Also may have been cost prohibitive to build the necessary scaffolding at that scale.
Societies find ways to fund what is important. That bridge might have been a grand piece of civil engineering, but it was comparable in scale or smaller than the pyramids and many other historical projects, all of which their societies afforded. Theory is that Easter Island society killed itself by deforesting the island to build its stone monuments. So, they bankrupted themselves doing it, but they still had the economy, the efforts of its people, to do so. This bridge would have served a vital transportation, logistical, mercantile, and military purpose, so easily justified with a good value on investment. And, it was the Ottoman's, a society that had treasures like Hagia Sophia and a vast empire - they could afford a few trees. Medieval Europe built their cathedrals with scaffolding. The Brits built their whole empire on timbers to sail the seven seas. We use the same amount of lumber for building forms to make modern concrete structures.
If you are going to build that much scaffolding might as well leave the scaffolding up and run a road on top.
Wood isn't durable. There is a current interest in modern uses of architectural wood, but historically there are few wooden structures that persist beyond a few centuries. Speaking of bridges, the comment brings to mind the conquest of the Wild West in latter 19th century United States. There were some huge railroad bridges slung across gaping chasms, supported by wooden trestles. But they were ephemeral, and to be ultimately durable, railroad bridges had to be built of iron.
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Prognostication... (Score:2)
Prognostication is not proof.
Da Vinci? (Score:5, Funny)
If Da Vinci were alive today there would be multiple /. posts in this thread by now about what a delusional egomaniac huckster he is and that the SEC is going to shut him down any day now assuming that Volkswagen doesn't eat his lunch first and he runs out of cash and goes bankrupt waarrrrgarbl etc.
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No, he'd be happily employed as a data scientist trying to market clothing.
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Well, to be fair, Da Vinci actually did all these things himself, instead of hiring legions of nameless smart people to do it for him, and then taking credit for it all.
Re:Da Vinci? (Score:4, Informative)
I re-watched the Secrets of the Dead episode about him today. It seems he was very much the entrepreneur type, though in a different society. He read a lot of books (Gutenberg's press being the internet of his day), and it seems he accumulated a lot of good ideas from other people, both recent and ancient, often fixing little issues with them. That's not to say none of his ideas were original. Also, many of his ideas never went anywhere, and had to be rediscovered in his papers 300 years later.
But the one thing I was convinced of was that he was a really good artist and sculptor.
And mentioning PBS, it seems that this bridge will be part of a Nova episode five weeks from now. (Nov 13)
Re:Da Vinci? (Score:5, Funny)
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Earthquake safe ? (Score:4, Interesting)
Re:Earthquake safe ? (Score:5, Interesting)
Not familiar with the roof technique you mentioned, but I actually watched a show recently about the effort to rebuild Kumamoto castle after an earthquake several years back [nippon.com] (a lot of famous Japanese landmarks have been rebuilt several times, so historically, this isn't all that unusual). The feudal architects had actually come up with an ingenious way of making those stone foundations more earthquake resistant by aligning the stones on the corners perpendicular to the arching slope instead of to the ground, which gave it more resistance to the earthquake shearing forces. Unfortunately, the application of that technique was spotty, since the buildings were all constructor or reconstructed at different historical dates. If I recall correctly, engineers only recognized the significance of that design element after the earthquake, since walls built with those techniques tended to hold up better.
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Re:Earthquake safe ? (Score:4, Informative)
Earthquake safe? Like some of the old Japanese roof techniques that interlocked to the building's frame? [I'm sure I did not describe that properly but hopefully a more knowledgable person will understand].
I saw a Nova show about Chinese buildings in the Forbidden Cities that sounds like that. You can find a short version of it at https://www.youtube.com/watch?... [youtube.com] . There is a link there to the full show. I thought it was pretty interesting how they came up with the interlocking frame parts for the building to move with the earthquake motion enough that it held up very well.
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The key to earthquake survivability for buildings like that is not to be too rigid. The Japanese developed techniques to build out of wood with interlocking parts. No metal nails. The whole building is able to move without cracking or collapsing.
There is a graveyard in Yokohama where many of the foreigners who first settled there are buried. Nearby there are some ruins of their houses. They built them on top of a hill and made them as strong as possible to resist the earthquakes, and then got buried in them
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Of course. Those white European Christians knew more than those godless savages. Why listen to someone who doesn't believe in your god?
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"He also apparently understood that the region was prone to earthquakes, and incorporated features such as the spread footings that would provide extra stability. To test the structureâ€(TM)s resilience, Bast and Xie built the bridge on two movable platforms and then moved one away from the other to simulate the foundation movements that might result from weak soil. The bridge showed resilience to the horizontal movement, only deforming slightly until being stretched
Why on earth did you post a CNET link, Beau? (Score:5, Informative)
CNET is basically just a clickbait aggregator these days. Don't drive traffic to them.
Go to the source.
https://news.mit.edu/2019/leon... [mit.edu]
Norway built that bridge (Score:5, Informative)
Proven when 130 ft for 18+ years (Score:4, Informative)
They built a small scale version [wikipedia.org] in Norway which was finished in 2001. Don't know about 500 years and 790 ft, but at least we have proof that 18 years and 130 ft works.
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I red the wikipedia article you referenced. That footbridge looks awesome & I'd love to visit it one day. However, I think the MIT article makes a good point
https://news.mit.edu/2019/leon... [mit.edu]
“That was not a test to see if his design would work with the technology from his time,” Bast says. But because of the nature of gravity-supported masonry, the faithful scale model, albeit made of a different material, would provide such a test.
“It’s all held together by compression only,” she says. “We wanted to really show that the forces are all being transferred within the structure,” which is key to ensuring that the bridge would stand solidly and not topple.
So the Norwegian bridge didn't provide the same proof of concept because it used modern materials & reinforcement techniques.
Shame they didn't build it (Score:2)
Back then it would have been one of the wonders of the world, I think.
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Not only back then, but still today ... because most likely it would still be there, despite the earthquakes.
A Masonry Arch Bridge then (Score:2)
Sure this bridge would have been exceptionally long, but that is not the writer is wonderous about. Nor has the design "held up" for 500 years. The design has simply existed for 500 years.
The main problem with such arch bridges is the enormous horizontal force they create at each end - at the abutments - not a
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Nitpicking?
Perhaps you missed the line which mentioned where the bridge was supposed to be build? that would connect Istanbul with its neighbor city Galata. I took the liberty to copy it for you. Google is your friend, I guess you see a nice image on google earth, too ...
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You complained about the ends of the bridge would need "special care" to be fixed.
So: you seem not to know where it is build.
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I know where the Galata bridge would have been built. What is that got to do with my point that any masonry arch bridge, wherever it is built, needs strong abutments to resist outward horizontal forces, especially one as long as this? The abutments may be natural (like between two rock faces) or constructed.
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Because the horizontal force is not on top of a flat surface, but at the flanks of a chasm, pushing directly into the bed rock.
Beauty (Score:1)
It should also be mentioned that the bridge is beautiful.
Material properties don't "scale" (Score:1)
That is a sexy bridge (Score:2)
Earthquakes (Score:2)