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Chapter 2 Using Multiframe
Linking Joints Or Master-Slave
Multiframe allows you to rigidly link groups of joints together so that they move together
in response to either static or dynamic loads. This has a twofold benefit. Firstly, it
allows you to simulate rigid structural elements such as a floor slab, and secondly it
significantly reduces the size of the stiffness matrix resulting in lower memory
requirements and faster analysis times.
Joints can be linked together on a degree-of-freedom basis. This means some degreesof-freedom can be linked together and others left independent. In the case of a rigid
floor slab for example, all the joints on that level could have their x, z and Øy deflections
linked together to simulate the rigid translation and rotation of the slab while still
allowing bending of the floor. When linking a rotational degree of freedom, Multiframe
automatically selects the corresponding displacement degrees of freedom that must also
be imposed to enforce rigid body motion in the plane of the rotation.
To rigidly link a group of joints

Select the joints to be linked in the Frame window

Choose Joints Linking from the Frame menu

Select a master joint.
In most cases the default master joint selected by Multiframe will be adequate. It is only
when linked group intersect that the Master Joint would have to be changed to a joint
contained in both linked groups of joints.

Type in a name for the group and select the degrees of freedom to be
linked
The linked group of joints is displayed as a shaded area in the Frame window. The
Master Joint in each group of linked joints is also highlighted using circle of darker
shading.
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