11 ms·
Why Bridges Don't Sink
- Terr_ 2y ago> But, what if you just keep loading it and causing it to sink deeper and deeper? I believe this is the same fundamental engineering method used in a swamp by Herbert's father in Monty Python and the Holy Grail. [0] [0] https://m.youtube.com/watch?v=w82CqjaDKmA https://m.youtube.com/watch?v=w82CqjaDKmA
- jonplackett 2y agoOne day son, this will be all yours! What, the curtains?
- bityard 2y agoWhen I started here, all there was was swamp. All the kings said I was daft to build a castle on a swamp, but I built it all the same, just to show 'em. It sank into the swamp. So I built a second one. That sank into the swamp. So I built a third one. That burned down, fell over, then sank into the swamp. But the fourth one stayed up. And that's what you're going to get, Lad, the strongest castle in these islands.
- Animats 2y agoThe real world version of that: The causeway for the Lucin Cutoff across the Great Salt Lake.[1] The Southern Pacific dumped in fill rock starting in 1902, and the rock sank into the sediment. But they didn't give up. They kept dumping in more rock. They still couldn't get above the water line. So they built wooden trestles on the foundation thus created. That worked, but the trestle was too weak and limited to slow trains. So eventually, the Union Pacific dumped in far more rock and built a solid rock causeway all the way across the lake. The causeway had to be raised in 1986 and strengthened. Today, it carries long UP freight trains, part of the transcontinental main line. [1] https://utahrails.net/pdf/UP_Great-Salt-Lake-Causeway_2007.pdf https://utahrails.net/pdf/UP_Great-Salt-Lake-Causeway_2007.p...
- slowmovintarget 2y agoThat's why there were five Babylon stations... JMS lifted the joke. Nice!
- srott 2y agoSome of them wont sink because they float... https://en.wikipedia.org/wiki/Nordhordland_Bridge https://en.wikipedia.org/wiki/Nordhordland_Bridge
- voxadam 2y agoThere are three floating bridges on Lake Washington in the Seattle area as well. The Lacey V. Murrow Memorial Bridge[0], the Homer M. Hadley Memorial Bridge,[1] and the world's longest floating bridge the Evergreen Point Floating Bridge.[2] [0] https://en.wikipedia.org/wiki/Lacey_V._Murrow_Memorial_Bridge https://en.wikipedia.org/wiki/Lacey_V._Murrow_Memorial_Bridg... [1] https://en.wikipedia.org/wiki/Homer_M._Hadley_Memorial_Bridge https://en.wikipedia.org/wiki/Homer_M._Hadley_Memorial_Bridg... [2] https://en.wikipedia.org/wiki/Evergreen_Point_Floating_Bridge https://en.wikipedia.org/wiki/Evergreen_Point_Floating_Bridg...
- wiredfool 2y agoAnd one on the bottom, no longer floating. (note -- was a bridge engineer in Seattle and did work on the old 520 bridge when we designed the retrofitted post-tensioning it in the late 90's. Among other tasks, I supervised a guy drilling holes in the bottom of the bridge with a concrete corer. )
- knute 2y agoI'm not an expert but I have seen Titanic (1997) and I would think a floating bridge is most vulnerable to sinking.
- rob74 2y ago> Quote-unquote “bedrock” is a simple idea, but in practice, geology is more complicated than that. There is always bedrock, but in some places your pile would have to be really long to reach it: > The gravel deposits of 100 m (330 ft) are the deepest in the south of Munich and decrease towards the north. (from https://en.wikipedia.org/wiki/Munich_gravel_plain https://en.wikipedia.org/wiki/Munich_gravel_plain - not saying this is anything really extraordinary, but it's the area I'm most familiar with)
- EdwardDiego 2y agoThe Otira Gorge Viaduct in New Zealand, that carries a highway that crosses the Southern Alps, has its foundations in a deep layer of talus that has fallen off Hills Peak over centuries - that movement of rock being why they built the viaduct to replace the road - as the slope eroded the road had to be moved higher up the slope, adding more switchbacks to the infamous Zig Zag [0]. Plus the falling rock that made the road dangerous. They were determined to hit bedrock, but yeah, was buried too deep. [1] [0]: https://teara.govt.nz/files/p-8788-gns.jpg https://teara.govt.nz/files/p-8788-gns.jpg [1]: https://www.stuff.co.nz/national/117150792/awardwinning-otira-viaduct-near-arthurs-pass-notches-up-two-decades https://www.stuff.co.nz/national/117150792/awardwinning-otir...
- quibono 2y agoTIL New Zealand have their own Alps!
- stonemetal12 2y agoTechnically "Alps" is the plural of "alp", which means a very high mountain.
- wongarsu 2y agoHowever "alp" comes from Latin "Alpes", which is the mountain range in Western Europe we now call the Alps. The word has become genericized to a degree. One the other hand Alps used to be one very specific mountain range, and alp a mountain in that mountain range, so surprise at some other place calling their mountain range Alps is understandable.
- bell-cot 2y agoFavorite bit: > The tagline of the Pile Driving Contractors Association is “A Driven Pile is a Tested Pile” because, just by installing them, you’ve verified that they can withstand a certain amount of force. After all, you had to overcome that force to get them in the ground. And if you’re not seeing enough resistance, in most cases, you can just keep driving downward until you do!
- deleted 2y ago[deleted]
- SideburnsOfDoom 2y ago> in most cases, you can just keep driving downward until you do! I feel that the cases in which that technique doesn't work are stories to be told. Do you just keep driving downward for a very long time? How long?
- 0xTJ 2y agoSatan, far below some very deep, soft, and slippery soil where an overpass needs to go: > What the heck?
- bell-cot 2y agoIANAE (No An Engineer), but I think he mentions both the issues of piles wandering off-course, and of unanticipated piling problems causing major budget & scheduling issues. From a structural PoV, an extremely long piling in soft-ish soil will start having problems with lateral deflection - which it is too thin (relative to length) to resist. Then there's the case of "we think we finally hit bedrock...but what if it's just a big boulder?". I can imagine cases of pilings running into large underground caverns, or penetrating strata containing water / gas / petroleum under pressure. Edit: From a quick search... In some locations, bedrock may not start until >1000' below the surface. And here's a very quick & simple intro to the fact that "bedrock starts at depth D" is usually too simplistic: https://education.nationalgeographic.org/resource/bedrock/ https://education.nationalgeographic.org/resource/bedrock/
- 2y ago
- abduhl 2y ago>> Your guess is as good as mine why the same steel shape is an I-beam but an H-pile. This is because the shapes are different. I beams are typically more slender through the web because the goal is to concentrate mass at the flange for moment capacity because they’re beams and geared towards bending. H piles are thicker in the web with the web thickness usually similar to the flange because the use case requires axial capacity and various constructability considerations. I beams turned into W (wide flange) and S sections in the standard shapes and H beams are called HP sections. You’ll often see them cross-specified for foundation work but it’s rare that you’d choose an HP section over a more efficient section like a W or S for something “out of the ground.”
- chasd00 2y agoThank you for this. In college, for some reason, i hung out with architecture majors instead of my fellow computer science people. They would talk about "w flanges" when, to me, they meant I-Beams. I never cared enough to ask but knew better than to try and correct them because that's pretty annoying heh.
- LegitShady 2y agoIt's good you didn't correct them because they aren't the same thing. Wide flange beams have wider flanges that don't taper or taper less than I beams. Your architecture friends were probably using the right lingo.
- pimlottc 2y agoImportant bit of background knowledge: "The horizontal elements of the I are called flanges, and the vertical element is known as the "web"." Useful graphic: https://en.wikipedia.org/wiki/File:I-BeamCrossSection.svg https://en.wikipedia.org/wiki/File:I-BeamCrossSection.svg
- VWWHFSfQ 2y agoKen Burns' documentary [0] about the construction of the Brooklyn Bridge was really fascinating discussing the innovative (at the time, late 19th century) engineering methods and challenges. It's pretty short, only 1 hour. Highly recommended. ]0] https://kenburns.com/films/brooklyn-bridge/ https://kenburns.com/films/brooklyn-bridge/
- HNDen21 2y agoRead this a few years back.. highly recommended The Great Bridge: The Epic Story of the Building of the Brooklyn Bridge by David McCullough https://www.amazon.com/Great-Bridge-Story-Building-Brooklyn/dp/067145711X/ref=tmm_pap_swatch_0?_encoding=UTF8&qid=&sr= https://www.amazon.com/Great-Bridge-Story-Building-Brooklyn/...
- VWWHFSfQ 2y agoOh yes McCullough narrated the Burns doc. Brilliant historian
- cyberge99 2y agoI have a guess to why H Pile i stead of I Pile: pronunciation. The initial I seems almost silent when saying I Pile. Whereas with H there’s a more distinct sound.
- dpcx 2y agoIsn't that the same with I-Beam as well?
- me_me_me 2y agoI-Beam rolls of the tongue H-Beam doesnt, I guess thats the reason for adopting I term over H term
- dpcx 2y agoThe context was the silent-ness of I vs H, not what rolls off the tongue. I agree that I Pyle rolls better, though.
- zardo 2y agoToo close to Apple's trademarked iPile
- gosub100 2y agoMy pet peeve along this line is O-ring. Is there any other conceivable shape for a ring?
- zardo 2y agoDoesn't that refer to the cross-section? https://www.allorings.com/x-ring-seals https://www.allorings.com/x-ring-seals
- antonellaleo 2y ago[flagged]
- mdrzn 2y agoTIL that "Piledriver" wasn't invented by WWE.
- samf 2y agoThe WWE didn't invent it, they perfected it.
- KolmogorovComp 2y agoTangential but does someone know the animation software used to display extract of the FHWA report, starting from 1:45? It seems to be used a lot by journalists and looks fantastic.
- relwin 2y agoThe bridge in the thumbnail is the Coronado bridge, rumored to have a floating hollow-box mid-section so that in the event of a collapse Navy ships can easily push debris and clear a channel. I remember hearing this "fact" on a San Diego harbor cruise long ago. Alas Wikipedia says it's a myth...
- surfingdino 2y agoSome do sink, on purpose https://en.wikipedia.org/wiki/Submersible_bridge https://en.wikipedia.org/wiki/Submersible_bridge, and some are mis-designed https://en.wikipedia.org/wiki/Lacey_V._Murrow_Memorial_Bridge https://en.wikipedia.org/wiki/Lacey_V._Murrow_Memorial_Bridg...
- lacoolj 2y agothis was such a great way to spend 17 minutes thank you for posting! I feel like I learned so much about foundations that I never would have otherwise on my own lol
- bloaf 2y agoThis guy’s videos are consistently great, they get a lot more technical than most other edutainment without getting bogged down.
- deleted 2y ago[deleted]
- quaintdev 2y agoShame that website does not have RSS
- jimbobthrowawy 2y agoI think all of the blogposts are just transcripts of videos from his youtube channel. You could use the feed from youtube to tell when there's a new release. Wait, I just checked the page source after writing the above to confirm and it looks like it does have one: https://practical.engineering/blog?format=rss https://practical.engineering/blog?format=rss
- quaintdev 2y agoThanks. Miniflux could not find it. I did not know that this can happen. Even authors are probably not aware of this.
- deleted 2y ago[deleted]
- deleted 2y ago[deleted]
- nanomonkey 2y agoThe Japanese Pile driving company, Giken, has some great engineering videos of their silent pile driving technology and some novel use cases, such as stopping a lava flow, or making underground bike storage in cities: https://www.youtube.com/@GikenGroup/videos https://www.youtube.com/@GikenGroup/videos
- chmaynard 2y agoAuthor: Grady Hillhouse Videos: https://www.youtube.com/channel/UCMOqf8ab-42UUQIdVoKwjlQ https://www.youtube.com/channel/UCMOqf8ab-42UUQIdVoKwjlQ Blog: https://practical.engineering/blog/ https://practical.engineering/blog/ Feed: https://practical.engineering/blog?format=rss https://practical.engineering/blog?format=rss
- eleveriven 2y agoThe design, materials, construction techniques of bridges are so fascinating for me