column design 1

hello
I have a concrete column with axial force (compr) and biaxial bending.
I would like to know, when can I ignore the non-principal moment and just
design as compresion+bending.

Is there an ACI recomendation.

I read something like the moment>20%of the principal-moment. Is that correct??
Also e/h=0.005??; I am not sure, Thank you very much.

 

[ishvaaag]

You find guide to this in EHE 43.5.3 article (of vigent spanish code for reinforced concrete).

Condition is

(ex/b)/(ey/h)<=0.25

eccentricity of load
ex lays on parallel to b
ey lays on parallel to h, actual depth.

The correspondent statement when the other orthogonal flexure is predominant is

(ey/h)/(ex/b)<=0.25

 

[JAE]

I don't think there is anything in ACI that lets you ignore a biaxial moment. Chapter 8 governs analysis and Chapter 10 governs column design and neither speak of what you are proposing. I also couldn't find anything in various text books and references regarding concrete design. All assume that if you have both moments acting under a load combination, you should include them in your analysis.

 

[ishvaaag]

I forgot to express that what such EHE clause permits is to substitute the biaxial check by 2 separate plane checks, P-Mx and P-My, not at all the dismissal of the weak moment.