3771x

000596

Dipl.-Ing. (FH) Robert Vogl

2021-01-18

Defining Releases Depending on Internal Forces

In RFEM and RSTAB, it is possible to define nonlinear properties of member releases. In addition to the activity diagrams and force-deformation relationship, you also have the simple option of using signs or limit values of the internal forces as criteria for the effectiveness of the release. This way, you can specify which internal forces should be transferred at the member end.

Axial Force Hinge "Fixed if positive N"

Axial Force Hinge for Compressive Forces

For example, if there is a hinge for the displacement in the longitudinal direction of the member ux, no axial force is transferred at the node. On the other hand, a hinge with the nonlinearity "Fixed if positive N" has the effect in which tensile forces (positive) but no compressive forces (negative) are transferred at the member end. Thus, the hinge is effective for negative axial forces: These internal forces are not transferred.

Moment Hinge "Yielding beginning from Release Moment"

Moment Release with Yield Criterion

The "Partial Action" nonlinearity type allows you to control the transfer of internal forces in a differentiated way. The example describes a restrained frame with a moment hinge in one of the corners. If a bending moment M_y of ± 6 kNm is exceeded, the connection should yield. In LC 1, this limit moment is not reached. A symmetrical moment distribution arises.

Yielding of Frame Joint

In LC 2 with an increased load, the hinge criterion applies: The moment is limited to the specified limit value. This leads to a redistribution of the internal forces and thus to an asymmetrical moment distribution.

Steel Frame Structure

Knowledge Base

KB 000596 | Releases Depending on Internal Forces

Author

Mr. Vogl creates and maintains the technical documentation.

Links

;