Moment Magnification Effects ACI
Moment Magnification Effects ACI
(OP)
Folks,
Is my understanding correct that if a concrete column is broken into a finite number of pieces along its height and I do a P-Δ analysis, I can set the δns factors to 1.0?
Is my understanding correct that if a concrete column is broken into a finite number of pieces along its height and I do a P-Δ analysis, I can set the δns factors to 1.0?






RE: Moment Magnification Effects ACI
RE: Moment Magnification Effects ACI
RE: Moment Magnification Effects ACI
I have a spreadsheet that computes δns factors for given moments and axial loads. I conservatively set βd to 1. I found that the δns values were more reasonable.
However, I was wondering since the column was broken into two pieces due to it being a two-story column, then would'nt doing a P-Δ analysis capture the effects of member curvature? I realize as JAE said in a previous post that in order to do the requirements of 10.1.1 right, I would have to sacrifice my first born to the analysis gods.
How do you folks account for member curvature in your analysis? Am I correct in assuming that if a non-sway column is not slender, then I can ignore the effects of member curvature?
RE: Moment Magnification Effects ACI
RE: Moment Magnification Effects ACI
RE: Moment Magnification Effects ACI
Unfortunately, the language in previous editions of the code (I'm looking at 2002), requires you to use the δns values for any non-sway frame. It doesn't really give you another option. For sway frame, they allow a P-Delta type of analysis in general. But, not for the non-sway.... Unless you want to comply with all the requirements of 10.10.1:
2nd order
material non-linearity
cracking
member curvature and drift
duration of loads
shrinkage
creep
interaction with foundations
But, of course, you would be crazy to want to comply with that secction. I laugh out loud every time I read that section... :)
RE: Moment Magnification Effects ACI