Releases definition

Degrees of freedom

Releases may be created for the following degrees of freedom related to the acting member force:


Degrees of freedom (local)





Vz*, My*


N, Vz, My


N, Vz


Vz*, Mx, My


N, Vy, Vz, Mx, My, Mz


N, Vy, Vz


*   displacements in global axes according to global coordinate system


For the members which member axis X’ is defined parallel to global axis, defined releases have global meaning.

Released/fixed degree of freedom is related to the local axis system defined for a member and is valid for the member begin and member end nodes.


Interpretation of releases definition corresponding to member forces:



Bending moment Mx

Bending moment My

Bending moment Mz

releases in rotational (angular) directions corresponding to released-partial fixed (spring) - fixed bending moment respectively to local X', Y', Z' axes

Axial force N

Shear force Vy

Shear force Vz

releases in linear  directions corresponding released-partial fixed (spring) -  fixed axial or shear forces  respectively to local X', Y', Z' axes


Dimension units


Dimension units for linear spring releases - [kN/m], for rotational - [kN∙m∙rad].


The default release is fixed by all degrees of freedom. For fixed release the default value is 1E111, for free release the default value is 0, for spring release the default value defined by range (0; 1E111).

In case all the member connected to the node all have free releases, kinematic undetermined situation is automatically internally solved by the software by changing one of the releases by a fixed one. In case the structure still is kinematic undetermined, the situation could be solved automatic by the software by using suggestions given during runtime of calculation.


Release name


You may enter releases manually in the grid. If you enter a (random) letter, release direction is fixed. If you type a number, release direction will become spring with the value you entered, except you enter zero - in this case release direction is free.

Release name starts with a default prefix 'R' and followed by a number. Release name recording starts with R1, every next release will get the next number. The default prefix may be changed in Options preferences.


Releases distribution and movement

Releases definition provides releases distribution and movement by nodal characteristic. There is a difference between 2D-, 3D-Frame and 2D-Grillage, 1D-Beam projects in MatrixFrame®. 2D-, 3D-Frame allow to assign releases to member nodes and to any other member parts generating new nodes in the positions, where the releases are assigned, so as result releases movement cause the related nodes movement. 2D-Grillage, 1D-Beam allow to assign releases to member nodes and to any other member parts not generating new nodes in the positions, where the releases are assigned, so in this case releases movement doesn't relate to nodes movement.

The releases definition is disabled in 2D/3D-Truss project because every 2D/3D-Truss structure member has releases at the member ends.


Appliance of Mx (free, spring) releases on member begin and end for 3D structures cause mechanical instability in local X'r direction and should not be admitted by user for both ends