A rotational restraint represents a discrete or continuous rotational spring about the longitudinal axis of a member.
RFEM 5 and RSTAB 8
A discrete rotational restraint (point rotational spring) can be entered using the menu "Insert" → "Model Data" → "Nodal Support" → "Dialog Box" / "Graphically" (see the image on the left) or the corresponding button, or in a table (see the image on the right).
Similarly, a continuous rotational restraint (continuous rotational spring) can be entered using the menu "Insert" → "Model Data" → "Member Elastic Foundation" → "Dialog Box" or in tables.
Entering in RF-/STEEL EC3 and RF-/FE-LTB
The rotation of girders susceptible to lateral-torsional buckling can be prevented in the case of the corresponding formation of connections by perpendicularly arranged girders (see the image on the left) or plates (see the image Discrete/Continuous Rotational Restraint). These act as point rotational springs (girders) or as continuous rotational springs (plates).
In RF‑/STEEL EC3, you can define the rotational restraint in the window "Parameters - Members" or "Parameters - Sets of Members." For this, select the "Rotational Restraint" check box. You can then enter the parameters of the rotational restraint in the settings. The rotational spring can be specified manually or calculated from the parameters of the discrete or continuous rotational restraint.
In RF‑/FE‑LTB, you can define the rotational restraint in the window "Elastic Member Foundation." The rotational spring can be specified manually or calculated from the parameters of the discrete or continuous rotational restraint.
RFEM 6 and RSTAB 9
A discrete rotational restraint (point rotational spring) or a continuous rotational restraint can be defined using the menu "Insert" → "Types for Members" → "Member Rotational Restraints" → "Dialog Box". In the New Member Rotational Restraint dialog box, select the type of the rotational restraint – continuous, discrete, or manual.
Then, define the properties of the rotational restraint in the second tab.
