Sir Dave,
I'm sorry, Im not yet verifying version2014.
im currently doing 2013 version.
here is the formula in the CII quick reference guide.
1. why Ia is multiplied twice to Fa/Ap?

SL = [(Ia |Slp + Sa| +Sb)2 + (2St)2]1/2
Where: Slp = PDi2/(Do2 - Di2)
Sa = IaFa/Ap
Where: Ia is the longitudinal force index

2. does Ia should not be less than 1.0?
because if I assumed Ia to be 1.0 my manual computation of code stress should be lesser than from result in Caesar, but its the opposite.