McComb's - Engineering Column Analysis 1

[Force15]

I have a question regarding McComb's Beam Column checks.
Specifically in page 3.4 where he's calculating Margins.

From the book:
"The largest resulting MS (or the least negative one) is used."
The ones he's talking about are
Case 1 :
MS = 1/(fc/fcr + fb/fbu) - 1.0
fc = compressive stress
fcr = allowable column buckling stress
fb = Mc/I (M varies based on loading and end constraints)
fbu = allowable bending stress

Case 2:
MS = Fc / (fc+fb) -1.0
Fc = Fcp (for K < 1.1)
Fc = Fcy (for K >= 1.5)
etc, etc....

Why should one use the higher MS? This is the first time I'm seeing something like this.

 

[rb1957]

certainly sounds odd ...

 

[rb1957]

reading the reference, i take it as one of the two methods is known to be conservative (or at least "probably conservative") and so should produce the smaller MS applying the larger of the two MSs means taking the most advantage of the structure.

he does follow through the procedure very carefully in his example, so it isn't a typo.