Beam Attributes: Rotation End Release

Description

Assigns rotational releases to selected ends of beam elements, with respect to the directions of the principal axes.

End releases change the way the end of the beam is connected to the node; rotational end releases can be Fixed, Released or Partial.

Rotation end release attributes may be applied to normal beams, user-defined beams and pipe elements.

In some cases, end releases can produce a structure with a singular stiffness matrix. For example, fully releasing both ends of a beam about the 3 axis direction will result in a rotational rigid body mode due to the fact that the beam is detached from both nodes in the twist direction.

Rotation end release attributes are independent of load and freedom cases.

Dialog

Rotation End Releases 1 / 2 / 3

Three components in the beam's principal axis system. Each component has three options that determine the state of the release in that direction:

Fixed

This is the default connection condition between the beam end and its node. A fixed condition means that there is no release, and the beam end it fully attached to the node.
Released

The beam end is completely disconnected from the node. The end of the beam is free to rotate independently of the node, about the released axis, just like a pin joint.
Partial

The beam end is attached to the node via a rotational spring with a prescribed stiffness. The spring provides the specified stiffness about the selected axis.

K1 / K2 / K3

The torsional spring stiffness about the 1, 2 and 3 beam principal axes, respectively.

Applicable to Partial releases only.

Common Controls

Units

Force×Length/Angle (e.g., N.m/rad, lbf.in/rad).

Common Uses

Beam rotation end releases are commonly used to model pin joints. A rotation end release can be applied about a single axis to model a 2D pin joint where the beam end is allowed to rotate about that axis while transferring moment about the other two axes.