Column Bending angle and Failure Mode 1

[mes7a]

Please see figure below of a column pinned on top and bottom. If there is a hole at the side at midspan, the column would deflect more than if there hole is at the base. Is this right? What is the principle called where hole at midspan would make it deflect more than if it occurs at bottom near base? Is it related to K factor or what?

 

[mes7a]

I don't have time today to go over the numbers, mes7a but the general idea seems okay to me.
In other words, you should be able to consider a contribution from the epoxy in addition to the steel.

There is something odd about the interaction diagram. At balanced point and using statics and resultant..
Pb = 0.85fc'ab + As'fs' - Asfs

And As'fs' is same value to AsFs but opposite reactions. In other words the opposite reaction
literally cancel out. So at balanced point. How can you still rely on the bars to resist the
axial load at the compression side when the tension side reactions cancel it out??