A rotational restraint is taken into account when determining the elastic critical moment or the critical load factor for lateral-torsional buckling, if this is determined by the internal eigenvalue solver. A rotational spring that is constant over the entire member or member set applies.
This option is not of interest for timber structures, as there are no studies considering a rotational spring in timber construction. Nevertheless, this option is provided for the sake of completeness.
Rotational Restraint Type
In the list, you can select various types of rotational restraints:
- Continuous
- Discrete
- Manually
Manually
You can also manually specify the rotational spring stiffness CD.
Assignment to Member or Member Set
Member rotational restraints have to be assigned to member supports. You can assign member rotational restraints to one or more member supports using the editing dialog box of the support. To do this, select the fictitious stiffness "Rotational restraint about x" in the "Nonlinearity / Fictitious Stiffnesses" list of the "Main" tab.
You can then assign the desired rotational restraint in the "Rotational Restraint" tab.
You can also graphically assign the member rotational restraint to a member support in the editing dialog box of the member rotational restraint by clicking the
button. However, the rotational restraint needs to be already assigned to a member support.
The member supports with the member rotational restraints defined therein are then assigned either to the members or to the higher-level member sets. Assign the member support by using the editing dialog box of the member or member set, the selection from the Member Support dialog box, or via the input table.