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OscarDiggs posted:To those wanting something a bit more visual, there is a guy on youtube by name of donoteat1 (who is apparently also a goon!) using Cities: Skylines to explain various urban planning concepts. So far he has done a video about the problems of free parking (https://www.youtube.com/watch?v=0lvUByM-fZk) and why urban freeways destroy communities (https://www.youtube.com/watch?v=rseaKBPkRPU). hello i made this AMA
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Aug 2, 2018 21:36
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| # ¿ May 10, 2024 22:08 |
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Nitrousoxide posted:What do you think is the biggest problem with urban planning in the US currently? I'm guessing the highway? I'd say a lack of regional planning with teeth -- regional planning exists but is almost entirely subservient to developer interests, with the possible exception of Portland, Oregon. Really the biggest problem is that so many problems in cities are unique to that particular city -- housing policies that make sense in the Bay Area might not make sense in Minneapolis or Philadelphia or somewhere like that. NIMBYism vs. YIMBYism is largely a false dichotomy I think -- problems like gentrification and displacement need to be considered on a human scale as well as on a statistical macroscopic level. I've been kicked out of an affordable apartment so it could be redeveloped into "luxury" student housing cubes. While I suppose that had some kind of regional depressing effect on rents, maybe, it directly resulted in a $200-300 rent bump and an unexpected and expensive move for the 20 people living in the building... And also parking minimums, of course -- but we can't actually practically end parking minimums in most cities since they're still absurdly car-dependent. Mass transit investment needs to occur alongside (if not before!) parking reduction. The oft-repeated mantra of "coaxing people out of their cars" requires something to coax the people into, after all. (And capitalism)
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Aug 3, 2018 22:50
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i did another video if anyone is interested, though it's more about historical urban water systems than any modern urban planning problems... https://www.youtube.com/watch?v=5MrkfLP25Rg
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Aug 14, 2018 16:48
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CountFosco posted:Could you elaborate on "tensile strength collapse"? That sounds pretty... uh, alarming. pre-stressed and/or post-tensioned concrete pre-stressed concrete: essentially you take a piece (or several pieces) of rebar, stretch it out 2-3 inches, then cast concrete around it, and when the concrete cures, you let go of the ends. now the concrete is in compression from the rebar trying to snap back into place, allowing it to span much longer distances since the tension forces acting along its lower surface are much lower (concrete is very strong in compression but fails almost immediately in tension) post-tensioned concrete: you get a cable with a big washer at each end, hold it taut, and cast concrete around it (or, sometimes, the concrete is pre-cast and you thread the cable through a hole.) then, once the concrete has hardened, you stretch out the cable and clip it so that the tension presses the washers against the concrete, holding it in compression and allowing it to span longer distances. both of these have the issue that if the rebar or cable fails, the entire concrete plank or whatever structural member fails. post-tensioning is more common today since you can go back and re-tighten the cables occasionally (up to a point - eventually they snap), as opposed to pre-stressing where you basically have to jackhammer out the whole thing to replace the rebar (now ask me about engineered lumber and oriented strand board)
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Aug 15, 2018 02:23
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SpaceCadetBob posted:What are your thoughts on engineered lumber and OSB? thanks for asking! so most older buildings tended to be built with old-growth lumber -- giant oak beams and the like (fun fact: most large-diameter oak beams are more fire-resistant than the equivalent steel section) but this proved uneconomical to build with en-masse, so balloon framing was developed where stud walls that we're all familiar with today bear most of the load. these are made of fast-growing trees like douglas fir. eventually this too proved to be uneconomical, so engineered lumber was developed to take advantage of the incredible technology of glue. a lot of great stuff came out of this like laminated veneer lumber (where thin sheets of wood are glued together to act as one larger board, nearly equivalent in strength to a huge old-growth timber but much cheaper) and dimensional wooden truss joists and a whole bunch of other fancy things which use less wood than simple dimensional lumber but have equivalent strength. oriented strand board is a form of engineered lumber which is effectively a plywood board made of woodchips glued together and compressed. it is a great way to practically use waste and is about as strong as plywood, and is frequently used as a substitute. all these products seem to show up again and again in these articles in the past two decades or so about wooden skyscrapers that are gonna arrive in 5 years, and a few truly fantastic buildings have been built which would otherwise have been impossible without engineered lumber. the issue arises when they are used cheaply, in cheap buildings. while you can use waterproof or water-resistant glue in engineered lumber, it is more expensive than the cheap non-waterproof glue. if the structural member will never get wet, this isn't a problem! and that's what engineers and especially developers expect for concealed structural members. the thing is, buildings leak, especially cheap buildings. so these fancy new engineered lumber joists and walls and beams quickly turn into so much papier mache once they're exposed to water for a few months, and the whole thing needs to be taken down and replaced. i've seen entire vertical sections of facades replaced because one tenant on the top floor decided to use the wrong kind of tile on their porch, and water was trapped underneath and seeped into the LVLs over 2 months and ruined the whole structure. so uh, engineered lumber is good if you use it right, but no one does, so effectively it's usually bad, especially in combination with cheap roofing and cladding systems. donoteat fucked around with this message at 03:47 on Aug 15, 2018 |
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Aug 15, 2018 03:39
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i made a thing https://www.youtube.com/watch?v=LdeirDrinWk
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Aug 22, 2018 13:24
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| # ¿ May 10, 2024 22:08 |
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figured y'all might enjoy this https://www.youtube.com/watch?v=zcxezjtw1Ak
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Oct 24, 2019 00:22
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