Effective lengths

The value of effective length factor is entirely your choice. The default value is 1.0 and is editable for flanges A & C. Any individual segment (for either flange) can be 'continuously restrained' in which case no lateral torsional buckling (LTB) check is carried out for that flange over that segment.

For a level to be treated as torsional restraint it must have both A and C restraint and also be restrained for compression buckling in both the major and minor axis.

There is no specific factor for destabilizing loads - you can however adjust the 'normal' effective length factor to allow for such effects.

To identify flanges A & C for an individual column, see Steel member orientation.

Lateral torsional buckling resistance

The LTB resistance is calculated from Equation 6.55.

LTB does not need to be checked for the following sections:

• circular and square hollow sections,

• equal and unequal flanged I/H sections loaded in the minor axis only.