Allowable Bending Stress, Unbraced Length > Lu

weron4u
Here I am again....

Are you talking about F1.1, F1.2, and F1.3? If so, each of these are defined for specific cases -

F1.1 - For compact sections only....this is where the flange/thickness and web/thickness meets the "compact" criteria in Table B5.1 AND ... your unbraced length is less than Lc which is defined in F1.1

F1.2 - For non-compact section

F1.3 - For either compact or non-compact BUT the unbraced length is greater than Lc.

In F1.3 there are also THREE equations for Fb - two of these are for specific conditions of l/rT...so you use the appropriate one. The other is another check on lateral buckling. You get the appropriate Fb from the appropriate Equation F1-6 or F1-7. Then you get another Fb from Equation F1-8. You use the larger of the two Fb's.

Thank you again JAE. Yes I was talking about F1.3, equations F1-6, F1-7, F1-8. That did answer my question. I needed to know to use the larger of the two values. Thanks again.