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deflection limits 1

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LKkk

Structural
Nov 7, 2024
4
Hello everyone, could you please tell me how we can define the deflection limits of (L or Lr, S or Wf, and D+L) as described in IBC Table 1604.3?
 
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From International Building Code (IBC) Table 1604.3 Deflection Limits :
Note i) reads " l = Length of the member between supports. For cantilever members, l shall be taken as twice the length of the cantilever. "

Therefore for each "position / condition" in the table, the allowable deflection is some fraction of length of the given member. For example: Roof member supporting plaster or stucco ceiling (member supported at both ends) :: L or Lr = (length of member)/360.
 
I'm going to use imperial units. Let's say you have a 20' span steel beam that's supporting a floor. The deflection under live load, L, would be

20ft x 12in/ft / 360 = 0.67in

The computed deflection of your steel beam must be less than 0.67in. So let's say you use the 384wL^5/5EI formula (if I remember correctly...probably not) for pin-pin deflection under uniform live load, and you get a deflection of 0.80in. That's more than 0.67in and it's not allowed, so you need to upsize your beam with a higher moment of inertia.

Remember to read all the little notes a through i. They don't usually apply, but sometimes they do! Hope this is helpful and what you were looking for, because I'm not 100% sure what you're actually asking. Good luck on your deflection endeavors.
 
From International Building Code (IBC) Table 1604.3 Deflection Limits :
Note i) reads " l = Length of the member between supports. For cantilever members, l shall be taken as twice the length of the cantilever. "

Therefore for each "position / condition" in the table, the allowable deflection is some fraction of length of the given member. For example: Roof member supporting plaster or stucco ceiling (member supported at both ends) :: L or Lr = (length of member)/360.
Thank you in advance!
 
I'm going to use imperial units. Let's say you have a 20' span steel beam that's supporting a floor. The deflection under live load, L, would be

20ft x 12in/ft / 360 = 0.67in

The computed deflection of your steel beam must be less than 0.67in. So let's say you use the 384wL^5/5EI formula (if I remember correctly...probably not) for pin-pin deflection under uniform live load, and you get a deflection of 0.80in. That's more than 0.67in and it's not allowed, so you need to upsize your beam with a higher moment of inertia.

Remember to read all the little notes a through i. They don't usually apply, but sometimes they do! Hope this is helpful and what you were looking for, because I'm not 100% sure what you're actually asking. Good luck on your deflection endeavors.
Thank you in advance!
 
Hello everyone, could you please advise which loads should be given first priority when designing CLT slab-to-wall screw connection details? Additionally, which type of screw arrangement is mostly recommended inclined or vertical to resist these loads and prevent connection failure?

Thank you!
 
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