To define node relationships

To define links between a control node and dependent nodes, use the following procedure.

A "control node" is one which is linked to its "dependent nodes" by one or more degrees of freedom. This defines a multi-point constraint condition. For example, a rigid link (dependent displacement and rotation) or displacement typing (e.g., beams which lie in different planes but are tied vertically). This is a more generalized method of linking nodes together than a floor diaphragm.

The following rules apply to node relationship assignments:

A node which is a dependent in one node relationship cannot be made a control in another node relationship. Conversely, a node that is a control in one node relationship cannot be made a dependent in another node relationship.
A node cannot be a dependent if it has a restraint or spring in any degree of freedom assigned to the control.
A node assigned to a diaphragm cannot be part of a node relationship.
A node cannot be a dependent if has an enforced displacement.

Select a set of nodes which have a relationship assigned.
On the Nodal ribbon tab, select the Node relationships tool in the Diaphragms group. The Assign Node Relationships dialog opens.
Specify the "control" node by either:

click Select and then select the node which will act as the control in the relationship in the graphical view

or
type the Control node number manually

Note: The control node does not have to be part of the selection set used to define the node relationship prior to opening the Assign Node Relationship dialog.
Select the Relationship between the control and dependent nodes.
- Rigid - all six degrees of freedom are selected as linked
- XY - this limits the node relationship to Fx, Fy, and Mz
- YZ - this limits the node relationship to Fy, Fz, and Mx
- ZX - this limits the node relationship to Fx, Fz, and My
- Custom - manually select the linked degrees of freedom: Fx, Fy, Fz, Mx, My, or Mz
(Optional) Click Preview to graphically display the linkage between the dependent nodes and the control node.
Click OK.

The program will validate the node assignments and then will assign the node relationship links from each dependent node to the control node.

Note: If any of the rules listed above are violated, the program will prompt you with an error.

Node relationship assignments can be edited by selecting the Node relationships tool in the Nodes group on the Spreadsheet ribbon tab.

To review the nodes that are part of a node relationship, select the Node Relationships tool in the Toggle Attributes group on the View ribbon tab. Nodes that are part of a diaphragm are highlighted green and the diaphragm number is displayed. The control-dependent node relationship is displayed graphically on the model using orange, dashed lines connecting each dependent to the control.