Neutral Axis Calculation for Concrete Columns Under Biaxial Bending

[mohamadh95]

How can the neutral axis of a concrete column under biaxial bending be determined. I mean if the load P is given along with the eccentricities ex and ey, how could the N.A. location and orientation be computed?
Thank you.

 

[paisiello2]

Since concrete and steel are both non-linear materials the only accurate way to do it is numerically using trial and error.

 

[mohamadh95]

Well I'm willing to make a program using Mathematica or a spreadsheet in excel in order to create the interaction curve of a column,so trial and error is no problem. Can you explain how shall I do it? Should I assume an initial N.A and then do the computations, and after that check if the computation check with the N.A assumed position?

 

[paisiello2]

That's pretty much it. Generally you have the vertical value of c and the rotation angle θ to locate it.

Now if you are doing an interaction curve that is a little different because now you are finding capacities which I think will turn out to be a little easier to do. A good reference is Collins & Mitchell's "Prestressed Concrete Structures".

 

[mohamadh95]

Thank you for your help.