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load limit rule
(lemmy.blahaj.zone)
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this post was submitted on 27 Nov 2023
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Fun fact about bridge load limits: school buses are legally allowed to ignore them. While this might seem insane given that the point of a school bus is to transport children safely, the posted load limit on a bridge isn't the weight which will cause the bridge to collapse - it's a weight which, if traffic heavier than that were to regularly use the bridge, would cause abnormally high maintenance and repair issues over the long term. Bridges can bear much greater loads than the posted limits without instantly collapsing.
Source: school bus driver who got a question about this on the test for his CDL endorsement and looked it up after going WTF?
what i've learned is that any piece of architecture should have like at least a 10x margin of error, you want it to tolerate astronomical degrees of fucking up.
You've also got dynamic loading to comsider, eg if a truck full of sand is driving across bridge and slams on the brakes, thats a nuch different impulse than just driving across normally.
I'd go for a food grade liquid tanker in this example. Muuuch more weight transfer as the liquid sloshes around, and food grade means no baffles to slow it at all.
Edit: spelling
Any old schmuck can make a structure with a 10x safety factor. The thing is making the safety factor as low as reasonably possible to minimize costs. If there's a regulation that says 3x minimum, you're probably aiming for 3x. Which is why those regulations are important, I guess.
Source: I write code for a living, don't listen to anything I say
https://safetyculture.com/topics/factor-of-safety/#typical-overall-factors-of-safety-1
Yep, I typically throw more steel at structures than required. If it 'looks' strong enough it is probably twice as strong as it needs to be. There are certain things like walkways that can meet design codes, but it would be bouncy and unnerving to walk on. Beefing up the structure also mitigates the 200lb ape factor i.e. more likely to stay standing if someone drives a forklift into it.