Based on my understanding of the description and the table I believe that this formula will do what you want: 
=LOOKUP(F23,INDIRECT("B"&LOOKUP(D23+0.49,A2:A21,ROW(A2:A21))&":G"&LOOKUP(D23+0.49,A2:A21,ROW(A2:A21))),B1:G1)
This assumes the input for the 1st parameter is from D23 and the input for the 2nd parameter is from F23. I did a "mock up" of what the table might look like so that you can see if it matches the results you expect from the actual data table.

Post Axial Capacity.xlsx

Hope this helps.