ACI 318 Definition of "Slender Walls"
ACI 318 Definition of "Slender Walls"
(OP)
I was recently going through the design code provisions for slender walls and I'm confused by some things that I'm seeing in ACI 318.
1) ACI 318-2008 section 14.8 never actually gives a definition of a "slender wall". Any ideas why this is, or am I missing something.
2) The old definition from the UBC days was whenever the H/t ratio was greater than 30. I think this went through a few slight modifications over the years. But, it was always pretty close to the classic h/t > 30 ratio.
3) ACI section 14.6 now has a section which says that "non-bearing walls" cannot have an H/t ratio greater than 30. Again, ACI fails to define what a non-bearing wall is.
If I'm following the new ACI code, can I still use my old trusted slender wall procedure (section 14.8) for walls with an H/t ratio greater than 30. Or, does section 14.6 prevent me from doing so?!
I was hoping that the IBC 2009 would have some additions or modifications to this section of the code to clear up these problems.... but, no such luck. :(
Can anyone else give me some insight on this subject?
1) ACI 318-2008 section 14.8 never actually gives a definition of a "slender wall". Any ideas why this is, or am I missing something.
2) The old definition from the UBC days was whenever the H/t ratio was greater than 30. I think this went through a few slight modifications over the years. But, it was always pretty close to the classic h/t > 30 ratio.
3) ACI section 14.6 now has a section which says that "non-bearing walls" cannot have an H/t ratio greater than 30. Again, ACI fails to define what a non-bearing wall is.
If I'm following the new ACI code, can I still use my old trusted slender wall procedure (section 14.8) for walls with an H/t ratio greater than 30. Or, does section 14.6 prevent me from doing so?!
I was hoping that the IBC 2009 would have some additions or modifications to this section of the code to clear up these problems.... but, no such luck. :(
Can anyone else give me some insight on this subject?





RE: ACI 318 Definition of "Slender Walls"
RE: ACI 318 Definition of "Slender Walls"
I would still use PCA Slender Wall Design, limiting the H/t to 50 as bewfore. None of mine have failed.
As for a bearing wall, neglecting the self weight of the wall itself, it is a wall where the joists and/or rafters are not parallel to the line of the wall.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: ACI 318 Definition of "Slender Walls"
It's the Masonry code that really required the slender wall procedure whenever H/t > 30. That makes sense because my slender wall design has almost always been based on masonry (at least up until this point). I don't see a similar requirement in ACI anywhere.
Regardless, it still strikes me as odd that masonry allows walls with an h/t ratio greater than 30, but that ACI doesn't seem to (based on section 14.6). Am I still missing something?
RE: ACI 318 Definition of "Slender Walls"