196

16501 readers

2774 users here now

Be sure to follow the rule before you head out.

Rule: You must post before you leave.

^other^ ^rules^

founded 1 year ago

MODERATORS

[email protected]

908

load limit rule (lemmy.blahaj.zone)

submitted 11 months ago by [email protected] to c/[email protected]

32 comments fedilink hide all child comments

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 31 points 11 months ago* (last edited 11 months ago) (1 children)

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?

[–] [email protected] 12 points 11 months ago (3 children)

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.

[–] [email protected] 4 points 11 months ago* (last edited 11 months ago) (1 children)

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.

[–] [email protected] 3 points 11 months ago* (last edited 11 months ago)

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

[–] [email protected] 2 points 11 months ago

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.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago)

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