Example: An exercise bike that can support 250 lb. Does the engineer find a large enough weight that deforms the bike, then take a fraction of that as the amount it can support?
In: Engineering
I am a licensed structural engineer so I like to think I can shed some light on this. I work primarily on residential projects so I’m going to give some examples of that.
Let’s say you have an uncooked spaghetti noodle that you’re holding. If you press at both of the ends, then it’s going to bend and buckle a little. If you Press enough it’ll snap. Now instead of pressing at the ends, just hold it flat and have a friend press straight down. Again, it’ll bend until you press it enough and it’ll break.
This is similar to how the posts/studs in your walls and the beams/joists in your floor work. Now sometimes we have spaghetti noodles that are much stronger, such as steel or engineered lumber. These can resist a lot more force before they bend too much or break. How do we know how much they can resist? There has been a LOT of testing done for products before they are accepted by the government, and there are guidelines for each of wood (NDS), concrete (ACI) and steel (AISC) all of which have loads of empirical data (meaning actual tests, not just math) for almost everything you can imagine.
So we use those, along with math, along with a little bit of creativity when required to make sure that your house won’t fall down.
There’s also wind and seismic but those are a lot more complicated so I won’t get into that for now. Hope that helps!
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