moment magnification for columns

[optiengg]

Should moment magnification be considered for sway frames, where the analysis has been made for various combinations of dead, live and earthquake loads. In such cases does it suffice to design column considering that it satisfies each and every loading combination, or do we still have to follow moment magnification factor method by separating gravity loads and lateral/earthquake loads and applying magnification factors.

 

[JAE]

Second order effects must be considered either by a rational analysis method that takes into account both P[Δ] effects and P[δ] effects, or by the ACI delta factors.

Using the ACI approximate method, you have to distinguish between "sway" moments and "non-sway" moments.

I'm not sure of your exact question, but simply analyzing a frame for the required load combinations does not deal with the second order effects (i.e. moment magnification).

 

[ash060]

If your frame is very short and your axial loads are not that great, you may not have much of a second order problem. You dont have to worry if your 2nd order moments are not 5% greater than your first order moments.