The KL/ry reported for a double angle does not match my hand calculations. I am designing the section per the AISC ASD 9th edition code.
For singly symmetric shapes such as Tees and Double Angles, the KL/r value for the Y axis is calculated by STAAD using the rules for flexural torsional buckling as explained in page 3-53 of the AISC ASD manual. It is not calculated as Ky multiplied by Ly divided by ry.