By no means an expert on this, but I will throw some answers in here to hopefully start the discussion and improve my own understanding.
1) Mpr for columns at each end will be same given that the same reinforcement is present at the top and bottom of column, isn't it?
- Yes I believe so, if they have all the same reinforcing/concrete and axial loads (see below)
2) How Pu is related to the Mpr values?
- You should be making a PM interaction diagram, in general, as you increase axial load (compression), your Mpr goes up.
-One oddity I see in your image, it looks like your are analyzing your wall pier for out of plane moment? Is that right?
-One area that I do not know standard practice on, do engineers do a worst case axial tension load and a worst case axial compression load for their seismic designs? Seems like differing Pu values could affect Mpr and the corresponding Ve? It might be the axial compression always controls the design, as you will get higher Mpr values with higher axial loads.
3) We will not have beams in this case. So check for Mpr of beams is excluded right?
- That's right, here's how I would do capacity based Ve determination
4) Ve shall not be less that factored shear calculated by analysis. What does this actually means?
Im a little unclear on this, but I think Ve needs to be the maximum of either the capacity based Ve shown above in my sketch or the factored up elastic Vu force. Which ever is greater is what you design the wall pier for. Essentially, you want to ensure the wall fails in flexural yielding before shear failure occurs.
