It is important to remember that a node is a point in space, therefore something intangible.
Now, most of the other objects: bars, tubes, elements, cables, etc. depend on directly or indirectly to nodes, therefore creating, editing, or removing them directly affects the others.
Add a new node
Selecting this menu brings up the edit window of nodes (which we will discuss below). We see the number of the new node and we will have to set its three coordinates in X, Y, Z .
If you click on a node in the structure, the coordinates X, Y, Z of the node appear in the corresponding boxes. We can change them and create one new node from another existing.
We can also define degrees of freedom for translations and rotations (using the six check boxes), the class of this node (drop-down) and if necessary, already applied external point loads at this node (remember that loads are entered in Analysis state).
If we want to create a node in the same place of another node, the program will warn us and not let us do it.
Once we created the node we can see it on the screen by activating the numbers of nodes or points representing nodes.
Editing a node means modifying some of the properties of the nodes which appear in the editing window. We can edit a single node or more than one, if the property we are going to modify are the same in all these nodes.
To edit a single node, press the right mouse button on the node (it must be highlighted) and a pop-up menu will appear. The second submenu is just for edit.
Clicking on this option displays the window on the right which is the same as we have commented before, but with the difference that all the data in the window are those that correspond to the node in question.
Another way to edit nodes is to use directly the menu Nodes | Edit. In this case, the mouse cursor becomes pointing finger that enables us to select the nodes we want to edit. We can do it one by one or by a selection window. The selection is ON/OFF type, i.e. if we pick a node already selected, we deselect the node. During the selection of nodes with window, we can move on and continue to select. When we finish selecting the nodes, we can modify values of the following properties of the node or the nodes:
If all selected nodes are of the same class, this value appears in the drop-down menu. If not, the dropdown menu is blank.
- No displacement
If all selected nodes have the same degree of freedom, the displacement boxes will be blank or marked with a ✔. If not, the check box appears gray.
This button serves to turn off all the displacement boxes. Therefore, it makes the node completely free. This button is used to select all the displacement boxes. Therefore, it makes a node fixed.
- No rotation
The same comment as in No displacement. These boxes are only visible if it is rigid node.
- Final coordinates
If we modify any of the final coordinates, the nodes edited become fixed nodes (displacement boxes are automatically marked with a ✔).
If the coordinate is preceded by the symbol ” @ “, the value is interpreted as an increase, not as an absolute value. For example if we enter @-2.5 in box X, what we are doing is to subtract 2.5 m from the X-coordinate of the nodes edited.
- External loads
First of all, we must remember that editing external loads is activated only in the Analysis state. The loads applied to the edited nodes will be entered as per the general axes X, Y, Z and in tonnes (t = 10 kN)
- Cp (Wind)
The same as in the previous case, this value is only editable in the Analysis state. This is the coefficient of wind that applies to the area that gravitates in the selected nodes. This value, however, is only active if you have selected the menu Calculate | Cp manual.
As this menu name shows, it serves to copy (replicate) or move a group of nodes, selected as usual: one by one or through a window. Once we have selected nodes, right click and get the window we can see on the left hand side.
- Firs, we must decide if we want to copy or to move the nodes.
- Then we fix the position of the displacement start. We can introduce values at X,Y,Z boxes (column “From”) or select a node from the screen to get its coordinates. If we left boxes in blank it means 0,0,0.
- We repeat the process for column “To”
- We can decide if after copying or moving nodes, they will be unified. In this case we can define precision to unify nodes.
- Finally we click “OK” to copy or move nodes or “Cancel” to abort any change.
It is important to notice that if we move nodes, we move all the objects (bars, elements, tubes…) that use these nodes. This allows to move parts of the structure independently. If we want to move the whole structure it is better to use menu Global|Translation, Rotation and Scaling.
The program displays a table of initial values of the nodes:
Node, Type, Class, Xini, Yini, Zini (initial coordinates), Px, Py, Pz, Pt (applied external loads), Cp (wind coefficient)
Type displays the permitted displacements of the node. The node of a rigid bar shows also permitted rotations.
Pt is the vectorial sum of Px, Py y Pz.
The program displays a table of final values of the nodes:
Nodes, Xfin,Yfin,Zfin (Final coordinates), Rx,Ry,Rz,Rt (Reactions at supports), dx,dy,dz,dt (Displacement of the nodes)
Rt is vectorial sum of Rx, Ry y Rz
dt is vectorial sum of dx,dy y dz
The program displays a table of values for support nodes:
Node, Rx,Ry,Rz,Rt (Reactions at supports), Mx,My,Mz (Moments at supports), dx,dy,dz,dt (Displacement of the supports. In general, these values are always zero, except in those supports that have some degree of freedom).
It is possible that many of these values are blank. For example, if the node is articulated Mx, My, Mz values will be null and void.
Rt is vectorial sum of Rx, Ry y Rz
dT is vectorial sum of dx,dy y dz
The program displays a table of the total loads applied at nodes: external loads + self weight + wind loads + snow loads + internal pressure + membrane prestress.
Initial coordinates = Final coordinates
It changes all the initial coordinates of the nodes and make them equal to the final coordinates. It doesn’t change anything else in the structure, just the coordinates of the nodes. Therefore, it is not exactly the same as the menu Global | Reset (initial form = final form), where in addition to modifying the initial coordinates of nodes, other structure adjustments are made.
Delete by numbers
This menu is used to delete nodes by their numbers. WinTess3 shows us a window which, in addition to some notes, allows us to enter numbers of the nodes that are going to be deleted.
If more than one you can use the comma dash code.
In this case, the mouse cursor is changed to pointing finger to select the nodes we wish to delete. We can do it one by one or in groups in a selection window. We must remember the ON/OFF selection method (if we pick a node already selected, we deselect it). Once the selection is completed, press the right mouse button and accept or cancel the action to delete the nodes selected.
Purge nodes means eliminating surplus nodes (that is, those nodes that not belong to any object: bar, elements, geodesic…) or those nodes that have some error in their data.
Move a node means changing its coordinates. Therefore, this could also be done through editing node. However moving nodes makes it graphically: select a node, drag it on to another node. To move a node in this way, another node in the final point of the movement must already exist.
It makes no sense to move nodes of a real structure. We will only use this menu in the state of Form finding and perhaps also in the state of Patterning. When we move a node, this node becomes a fixed node (displacements not allowed), since it makes no sense to move a node then change position during the subsequent process.
One of common utilities of this menu is to place fixed points on arches or any other auxiliary line that we have created during the state of Form finding.
There are situations in which two nodes are so close that create confusion on the screen. A typical case of this situation is presented when you import a DXF file, where the CAD program can generate nodes as close as thousandths of a millimeter, which remain as two independent nodes and that tend to be the cause of errors.
As soon we execute this menu, WinTess displays the window on the right where we are asked the distance of unification. This means that all the nodes whose distances between them are less than the value entered will collapse into a single node. This will affect bars, elements, cables, etc. in a transparent manner (the user doesn’t need to do anything).
With this menu, the program draws normal vectors to the membrane surface. These vectors are used by the program for various functions: calculate the strength of the wind on the membrane, render the membrane, etc.
These vectors can also be exported to DXF the file via the menu File | Export DXF, one of the layers is precisely in these normal vectors to the surface.
Renumber a node
If for any reason you wish to renumber a knot, use this menu. The cursor will change to selection finger. Selecting the node opens up a window with the current number of the node. We can then change the number in the value field.
It must be taken into account that renumbering a node actually affects two nodes since the node that has been affected gets the value of the node that we have renumbered. So if the node 10 becomes 28 (as we enter so), as a result, node 28 will become 10. This will affect bars, cables, elements, etc in a transparent way (the user should do nothing) .
Renumber all nodes
With this menu, all the nodes of the structure is renumbered. WinTess3 follows an algorithm from left to right and from bottom to top (on plan, axes X,Y). Therefore, it is sometimes necessary to rotate the structure for the renumbering will have the desired effect. This is typically done to reduce size of stifness matrix of the structure. This will affect bars, cables, elements, etc. in a transparent way (the user should do nothing).
Locate a node
|Often, we need to know location of a particular node to assess the displacement, for editing, etc. When the structure has many nodes, this work cannot be done with the naked eye looking at the screen. WinTess3 provides this tool as seen on the right, through which we enter the number of the node that we want to locate. Immediately, a large red dot appears on the screen to show the node in question.|
Numbering of the nodes on the screen can be a little chaotic when there are many nodes in the structure. However, it is typical that we need to know numbers of the supports, for example to compare the numerical results of the reactions obtained in the calculation.There are, obviously, other reasons as well.
Through this menu we number only auxiliary nodes. These nodes don’t belong to the structure and they are only useful (as their name shows) as auxiliary objects to create, copy or move other objects in the structure.