## Do you calculate the amount of load a beam can take based on when the beam cracks?

like if I was to say "this beam can take this much load" does that mean if you put any more load on it, it will crack? Sorry if this is a confusing question, help my understanding if you can.
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 Quote by perfectchaos180 like if I was to say "this beam can take this much load" does that mean if you put any more load on it, it will crack? Sorry if this is a confusing question, help my understanding if you can.
No not generally. Normally the "amount of load" a beam can take depends on what criteria you are governed by. For example, if you have a regulation that states you cannot exceed 80% yield, then you are limited to that.

The yield point of the material is what you are concerned with generally, i.e. the point at which the material no longer remains elastic and starts to deform permanently.

So... "if you put any more load on it, it will permanently deform" is probably the statement you are looking for.

CS

 Quote by perfectchaos180 like if I was to say "this beam can take this much load" does that mean if you put any more load on it, it will crack? Sorry if this is a confusing question, help my understanding if you can.
As stewartcs mentioned there is usually a limit on the principal stress in the beam. The yield stress is the stress at which permanent (plastic) deformation begins and a beam will be permanently deform. The criterion may depend on the application and margin to permanent deformation. I've seen criteria as low as 2/3 of yield strength.

Normally beams are designed to operate in the elastic region of the stress/strain domain, i.e. less than yield.

## Do you calculate the amount of load a beam can take based on when the beam cracks?

 Quote by perfectchaos180 like if I was to say "this beam can take this much load" does that mean if you put any more load on it, it will crack? Sorry if this is a confusing question, help my understanding if you can.
You may be also looking at working stresses in which a safety factor (commonly anywhere from 1.1 up to 5) is included.
 I was wondering something along the same lines as the OP. Say you have a steel beam which is a major support for any kind of structure, how do you know how much the beam can hold? Wouldn't direct testing on the beam itself lead to a weakening of the beam? And if you tested another beam of the same material and applied the results of this testing on the beam you intend to use, what is to say that the beam you choose to use doesn't have a crack or something which would weaken it? Is this where safety factors come into play? Thanks

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