Interaction Diagram Concrete Wall
Interaction Diagram Concrete Wall
(OP)
This might seem a silly question but when calculating an interaction diagram for a concrete bearing wall for out-of-plane forces what is the Pn,max? The ACI code points you to the columns section which says that your Pn,max is a portion of your Po. The reduction is based on whether you have ties or spirals that conform to code requirements. Because I'm looking at a wall I don't have ties or spirals. Should I use the full Po with no reduction or be conservative and use the smallest value (0.80Po)? That doesn't seem right but I can't find anything specific. Thanks.






RE: Interaction Diagram Concrete Wall
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.
RE: Interaction Diagram Concrete Wall
Most of the time you wind up with it being controlled by the flexural reinforcement anyway. (I.e. the (compressive) axial load is just gravy.)
RE: Interaction Diagram Concrete Wall
RE: Interaction Diagram Concrete Wall
Not sure I'd want to rely on that connection (i.e. between the 2 bars; or it even being there in some cases). But I guess it just depends on how daring one wants to get.
RE: Interaction Diagram Concrete Wall
RE: Interaction Diagram Concrete Wall
I usually take WARose's approach and limit the upperbound axial to plain concrete which is similar to how the masonry code looks at the axial strength ie the contribution of the reinf. is ignored if it is not tied.
RE: Interaction Diagram Concrete Wall
The masonry analogy is a good one. A lot of times when checking a wall after I've drawn my crude/conservative, lower bound interaction diagram (i.e. consisting of 2 straight lines connecting 3 points (max. P, pure max. bending capacity, and tensile strength based on vertical re-bar capacity)), I've back checked using a working stress design approach. (Similar to masonry.)
RE: Interaction Diagram Concrete Wall
RE: Interaction Diagram Concrete Wall
So you'd have to tie your longitudinal rebar if you need it for compression under ACI 318-14, even if it's under 1% steel.
RE: Interaction Diagram Concrete Wall
RE: Interaction Diagram Concrete Wall
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.
RE: Interaction Diagram Concrete Wall
That was my assumption as well. I assumed that in 'fixing' the double negative from ACI 318-11 and prior, they accidentally changed the meaning.
Been trying to clarify with an ACI 318 committee member and code consultant and at least his first response seemed to double down on current wording of ACI 318-14, that the OR is correct.
RE: Interaction Diagram Concrete Wall
As it stands, a basement wall with >1% I.F. reinforcing would need to have its verts tied. Our contractor friends would love that. I'd say no, like Ofred refusing to stone Ofwarren to death in The Handsmaid's Tale. Sometimes my wife forces me to watch what turns out to be really good television.
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.