# Rotational Restraint

### Glossary Term

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A rotational restraint is a point rotational spring or continuous rotational spring about the longitudinal member axis.

#### Entering in RFEM and RSTAB

A discrete rotational restraint (point rotational spring) can be entered using the menu 'Insert' → 'Model Data' → 'Nodal Support' → 'Dialog Box' / 'Graphically' (see Figure 01 on the left) or the corresponding button, or in a table (see Figure 01 on the right).

A continuous rotational restraint (continuous rotational spring) can be entered using the menu 'Insert' → 'Model Data' → 'Member Elastic Foundation' → 'Dialog Box' (see Figure 02 on the left) or in tables (see Figure 02 on the right).

#### 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 Figure 03 on the left) or plates (see Figure 03 on the right). 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 (see Figure 04).

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 (see Figure 05).