Story height for Drift Calculations 1

[Structintern3]

Hey Guys,

So I'm doing nonstructural cladding calcs for drift, and my quesiton is: is the story height always the floor to floor height? Let's say you had a steel beam in between the 2 stories that separates the cladding framing, would the story height be reduced or would you still consider it floor to floor?

Thank you!

 

[driftLimiter]

So I'm doing nonstructural cladding calcs for drift

Seems like perhaps you are confusing something, perhaps just the terminology....

Story Drift is generally referring to lateral displacement of the MLFRS.
For non-structural components we have relative displacement requirements.

I can point to ASCE 7 Ch 13 for you to consider how the displacement requirements are managed for seismic.
Section 13.3.2 of ASCE 7 -16 provides some discussion and equations used to limit seismic motion of non-structural.

If you want the relative displacement this part of the code says you can take it between the ends of the connected member. If you have cladding that goes from floor height, half way up to the next floor then that would be the height used.

Hope this helps, if were able to provide some more info on exactly what you are checking and the geometry perhaps I could help more.

 

[Structintern3]

@driftlimiter

Thank you for the response, I think we're on the same page. Basically, my understanding is the connections of nonstructural studs to the structure have to accommodate the story drift(or relative displacement?) I think I'm not fully understanding the difference between the 2. I've always been told we design our connections(drift tracks/clips/etc) to accommodate drift. Now I'm not really sure which one it is between the 2 you mentioned

 

[driftLimiter]

Yes if the element spans from floor to floor, the relative displacement you need to design for is perhaps the story drift.

But if the element doesn't span all the way, then it would experience less displacement when the whole story goes to its drift limit.

There is a figures in ASCE7 commentary C13.3-4 but its not the best.

FOr seismic relative displacement, if we don't know the specific displacement of an intermediately attached component, were permitted to scale down the story drift. See equation 13.3-8