Would you drive under this plyon? - Page 1
Forum section: electronics / general

author: Avacee
author_rank: Unknown
timestamp: April 19, 2017, 04:14:46 pm
content: http://www.bbc.co.uk/news/world-asia-39645534Go on, dare you! - your vehicle is a Faraday CageWhat goes poof just after it starts to fall? .. Is that part of the design in case of a failure?

author: Tom45
author_rank: Frequent Contributor
timestamp: April 19, 2017, 05:15:12 pm
content: What the brave soul (idiot?) that was spraying water on the fire?

author: bsudbrink
author_rank: Frequent Contributor
timestamp: April 19, 2017, 06:26:50 pm
content: Sort of like a scene from an old Godzilla movie.

author: Red Squirrel
author_rank: Super Contributor
timestamp: April 20, 2017, 04:41:58 am
content: We must construct additional pylons!

author: Vgkid
author_rank: Super Contributor
timestamp: April 20, 2017, 06:05:28 am
content: Quote from: Red Squirrel on April 20, 2017, 04:41:58 amI'm surprised this comment didn't happen sooner.

author: R005T3r
author_rank: Frequent Contributor
timestamp: April 20, 2017, 09:24:29 am
content: Never heard about crane-truck contact?

author: jm_araujo
author_rank: Regular Contributor
timestamp: April 20, 2017, 10:53:47 am
content: I'm waiting for the conspiracy theorists to say that it must have been an inside job, open air flames (like fuel) can't melt steel beams

author: jeroen79
author_rank: Frequent Contributor
timestamp: April 20, 2017, 11:18:49 am
content: it must have been an inside job, open air flames (like fuel) can't melt steel beams

author: TerraHertz
author_rank: Super Contributor
timestamp: April 20, 2017, 01:24:54 pm
content: The transmission line circuit breakers trip just as it's starting to tilt, with those arc-overs as the cables get too close to the pylon. So after that point it's all mechanical. Thin sheet metal Faraday cages are moot, when it comes to tons of falling steel girders.That said, after it gets hung up by cable tension, I would drive under it - for enough money.As for building (slum) fire 'melting' steel - no, but it can get thin steel girders hot enough to go soft. And those pylon girders are thin. The important point being that their thinness prevents much heat loss by conduction from the section within flames, along the girder to cooler areas. Also the absence of fire insulation on the pylon girders, unlike the very good fire protection all steel frame skyscrapers have around the pillarsFor what fire does to thin, unprotected, low thermal mass steel girders, I'm sure everyone has seen the twisted tangles of collapsed steel roof girders after fires in small factories.Otoh, building fires cannot heat steel up enough to form rivers of bright yellow molten steel flowing out the window openings of a skyscraper. And yet there are multiple clear videos of this happening in a specific case.

author: zl2wrw
author_rank: Regular Contributor
timestamp: April 21, 2017, 06:39:14 am
content: Quote from: TerraHertz on April 20, 2017, 01:24:54 pmIf you are talking about the skyscrapers that I think you are, "ordinary" building fires do not involve the high speed injection of tens of tons of aluminium (plus the chemical oxygen generators and portable oxygen cylinders which are typically carried with said mass of aluminium).I understand that the oxidation of aluminium is so exothermic that it can rip oxygen atoms off of iron oxide, resulting in bright yellow molten iron (thermite reaction). Aluminium is also capable of stealing oxygen atoms from H2O, resulting in aluminium oxide, hydrogen gas and a whole lot of heat! (ask the British navy about the Falklands war...) - a broken water pipe (toilets on each floor in those skyscrapers?) and or fire sprinklers would be a source of oxidiser for an established aluminium fireYes, it is hard to ignite aluminium, but a bit of oxygen enrichment (see above) will fix that...

author: German_EE
author_rank: Super Contributor
timestamp: April 21, 2017, 02:54:36 pm
content: No way would I drive under that pylon if I knew that there was a fire at its base, I would park 100m away and watch what happens though. The big surprise is that the authorities didn't stop the traffic once the fire had started!

author: chris_leyson
author_rank: Super Contributor
timestamp: April 21, 2017, 05:03:02 pm
content: Hot rolled steel starts to loose its strength at around 300C and at 500C it's down to half strength so I'm not surprised the legs failed. Static load on the structure is maybe around 40 to 50 tonnes.