Slender Shear Walls

[RFreund]

This applies to masonry and concrete, but I suppose the focus is on concrete for me, for now. - Are there any provisions that limit the slenderness of a shearwall? Assume that the shear wall is connected to the framing such that no vertical load is transferred to the shear wall (i.e. some sort of deflection clip). Is there a way to check buckling of the wall? Like an effective end width that acts as a column? Also assume this does not need to meet any ACI Ch 22 requirements for seismic.

Thanks,
Ryan


EIT

http://www.HowToEngineer.com

 

[KootK]

There's an h/25 rule in ACI or something like that? I've seen high seismic authors recommend as little as h/15. If you have access to the MacGregor/Wright concrete text they go through a first principles example for a shear wall. Not sure how accurate that is but its plenty impressive.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[RFreund]

Thanks for the reply Koot. It's odd that I can't find much on this.

EIT

http://www.HowToEngineer.com

 

[slickdeals]

There are provisions for slenderness in ACI 318-14, seismic chapter. This was something that was added recently.

 

[KootK]

It's odd that I can't find much on this.

I thought the same. I think that it's the case that it's just something that hasn't generated many failures other than in rather extreme seismic/testing conditions so we've collectively decided not to get our undies in a bunch about it. We tend to discretize our analysis of shear walls such that we're studying column like boundary elements. In reality, however, these thing behave much like vertical plates when it comes to stability. The interiors of the walls brace the boundary elements substantially. Vertical plates 10-12' tall and 8-14" thick tend not to buckle often. And that's great.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[MrHershey]

Probably worth noting this is an area of active research. Investigations of structural failures following the 2010 Chile and 2011 New Zealand earthquakes found numerous instances of wall boundaries buckling after yielding.

As I understand it, it's not so much buckling of the entire wall (though that's important too), but more of a local buckling failure at the extreme compression region/boundary zone that can then become more of a global buckling failure.

See Parra and Moehle's article in the current ACI Structural Journal: Link

 

[RFreund]

Thanks for all the responses.
I am looking at the use of some thin concrete walls in general. Some lightly loaded with larger lateral loads. Some with large axial loads and interestingly enough the limiting factor for most of these walls is that the ratio of second order moments / first order moments must be less than 1.4. It doesn't seem like you can get around that.

Thanks again!


EIT

http://www.HowToEngineer.com