U2, P-delta and k, about CISC

[burtonli]

Some engineers told me, when we use U2, we don't need condiser the effect of k > 1.

I used SAP200 to calculate a cantilever column W14X665.
L=500", P=-1191kip, v=5kip, Mz=2000kip-in.
for K=2, Ce=1193kip, Cr=1005kip.
In this case, U2=1.1, if k=1, stress ratio=0.5
k=2, ratio=1.3
P-delta analysis, defletion >10" (numbers may be not exact )
duckling p is same as Ce (deflection > L).

Can anyone explain k is not necessary for sway permitted frame?