When calculating the beam bending capacity considering lateral torsional buckling, M_bx, of an unbraced segment, the program calculates α_m based on the maximum moment in a segment and the moment at the quarter points along the length of the unbraced segment. Although not required by Code, you may conservatively specify that α_m be set equal to 1.0 for all simple span noncomposite beams. You may also specify that α_m be set equal to 1.0 for all cantilevers, as recommended by the Codes and other sources. Otherwise, the program will calculate and use the values of am as allowed by the appropriate Code.

The output shows the values of capacity, unbraced length, and α_m at the points of maximum and minimum moments as well as the controlling condition. Note that the controlling condition may not correspond to any of the maximum or minimum moment conditions. This indicates that the controlling condition occurs in a segment with a lesser moment but greater unbraced length.