Solver nodes
Fixed degrees of freedom
Solver nodes have six degrees of freedom (DOF) with respect to their user coordinate system (UCS). When one or more DOF has been fixed, (which you can do for example by creating a support at the node location), this is indicated in the solver view as follows:
- A single arrow in a particular direction indicates translational fixity
- A double arrow indicates rotational fixity about a particular direction.
| Solver node degrees of freedom | DOF Symbol |
|---|---|
|
Translationally fixed in Fx, Fy, Fz. Rotationally released: Mx, My, Mz |
 |
|
Translationally fixed: Fx, Fy, Fz Rotationally fixed: Mx, My, Mz |
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The UCS does not necessarily have to match the global coordinate system, for example:
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If you rotate a supported column around its axis, the UCS would rotate to match the column.
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If you incline and rotate a support applied to a node, the UCS would also incline and rotate.
Coincident solver nodes and coupled degrees of freedom
When you apply wall releases to panel side edges or top/bottom edges, this can necessitate the formation of coincident solver nodes. The coincident nodes will either be coupled, or uncoupled.
Coupled coincident solver nodes
Coupled coincident solver nodes will occur for example, where you have modeled a Pinned wall panel edge connected to a Fixed or Continuous wall panel edge.
They are indicated in the solver model by a dotted triangle symbol above the coincident nodes.
Two coupled coincident solver nodes are shown above. One of the nodes (136) has been designated the Leader and the other (715) the Follower. The Leader’s tooltip indicates its Follower node, the Follower‘s tooltip indicates its Leader node and the degrees of freedom that are coupled. The coupled degrees of freedom are also listed in the Properties window for the Follower node.
| Solver node | Tooltip | Node properties |
| Leader |  |
 |
| Follower |  |
 |
Tip:
Because coincident node symbols are not easy to see without zooming in, you can locate them by selecting Highlight coincident nodes on the Solver ribbon.
Uncoupled coincident solver nodes
Uncoupled coincident solver nodes will occur for example, where you have modeled a Disconnected wall panel edge connected to a Fixed wall panel edge. In this case, because the edges can move independently, a Leader/Follower relationship is not required.
Uncoupled coincident nodes are indicated in the solver model by a V shape symbol above the nodes. As there is no leader/follower relationship the only information included in the tooltip is the node coordinate.
Coincident Node Examples:
Consider two walls connected at an edge as shown below:
In a Review View, you can use the Show/Alter State> Releases command to set one of the edges as Pinned.
After analysing the model, if you open a Solver View, and click Highlight coincident nodes on the ribbon, all of the coincident nodes are identified.
Zooming in, you can see that the coincident nodes are coupled and leader/follower relationships have been created.
Returning to the Review View, if you now change the edge to Disconnected...
…after re-analysing the model, and returning to the Solver View, you should find that the coincident nodes are now uncoupled.
Diaphragm constraints
In the Solver View unconstrained nodes are shown as hollow circles, whereas nodes that are constrained by rigid diaphragms are shown as filled circles.
| Solver node constraint | Symbol |
|---|---|
| Node not constrained by a rigid diaphragm |  |
| Node constrained by a rigid diaphragm |  |
Nodes constrained by a rigid diaphragm will deflect so that the relative distances between them are maintained in plane. For nodes constrained in this way, the diaphragm number will be indicated in the solver node properties.
Individual solver nodes can be excluded from their constraining diaphragm If required. For instructions on how to do this, see: Include or remove solver nodes from the diaphragm.
For further information about diaphragms, see: Overview of diaphragm action in roof panels and slabs.
Solver node properties
When in a Solver View, solver node properties are displayed in the Properties Window as shown below.
| Property | Description |
|---|---|
| Fx, Fy, Fz |
The translational degrees of freedom at the node.
|
| Fx, Fy, Fz |
The rotational degrees of freedom at the node.
|
| Coordinate | The node location. |
| P-Delta |
When using second-order analysis the accuracy of the result will increase with the number of nodes within members. Within a member the number of internal nodes is determined by the number of incoming members. Tekla Structural Designer will add a P-Delta node into a beam or column if there are no incoming members. See also: Member second-order (P-δ) effects |
| Exclude from Diaphragm | If checked, the node has been excluded from the diaphragm. For instructions on how to do this, see: Include or remove solver nodes from the diaphragm |
| Diaphragm # | Specifies the diaphragm number to which the node is connected. (Not displayed when viewing the "Working Solver Model"). |