Documentazione SkyCiv

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SkyCiv Structural 3D

  1. Casa
  2. SkyCiv Structural 3D
  3. modellismo
  4. supporti



Supports need to be added in order to restrain the structure. If no supports were present then the structure would not be static and be unsolvable. It is important to remember that a structure must be restrained in every direction at some point by any of the supports. vale a dire. every degree of freedom must be accounted for by at least one ‘F’ nella struttura.

Similar to the connections between members, the supports are given a 6-digit code to specify which of the node’s degrees of freedom are restrained. Each of the degree of freedom’s must be defined as either Fixed ('F'), Rilasciato (‘R’) or Spring(‘S’). The degrees of freedom are in the following order:

  • X Translation
  • Y Translation
  • Z Translation
  • X Rotation
  • Y Rotation
  • Z Rotation

Ci sono 3 types of letters (or of releases) Puoi usare:

  1. “F” – Fisso – This means the degree of freedom is fully fixed and the member will transfer this force to the node
  2. “R” – Rilasciato – The force is not being transferred for this degree of freedom
  3. “S” – Primavera – The force is being transferred with some stiffness factor. This will require additional input.

A pin support (which only allows rotation about the z-axis) would be denoted by the code ‘FFFFFRwhereas a roller (which allows rotation about the z-axis and movement in the x-direction) would be given the code ‘RFFFFR’.

Supports can be selected from the pre-configured support buttons. Along with their fixity codes, questi includono:

  • Supporto fisso – ‘FFFFFF’ – Fixed in all translations (X,e,con) and rotations (Mx, Mio, Mz).
  • Appuntato (Cerniera) Supporto – ‘FFFFFR’ – Fixed in all translations (X,e,con) and but free to rotate about the z-axis (in this 2D case).
  • Supporto a rulli (in x) – ‘RFFFFR’ – Free to ‘rollalong the x axis and rotate about the z-axis.
  • Supporto a rulli (in y) – ‘FRFFFR’ – Free to ‘rollalong the y axis and rotate about the z-axis.
  • Supporto primaverile (in y) – ‘FSFFFR’ – There is a spring support allowing some force to be transferred in the y translation.

Any support outside of these pre-configured ones can be manually typed into theRestraint Code” campo.

When supports are applied, the fixity codes are based on the global axis of your project, not the local axis of the member that is connected to it. For more information on these fixity codes, please visit our blog piece on Fixity codes.


Settlements are movements of the supports of a structure. It can occur if the supports/foundations are not fully compacted, and soil settles around it. To model settlements, click into the “Supports” menu, and then click the “Settlements” button on the top right.
Settlements can only be applied to nodes that have a support specified at that node. The amount of translation or rotation of the settlement can be specified in the form.

Supporti a molla

SkyCiv offers the capability of adding spring supports in any direction/rotation. Users can partially restrain a degree of freedom with spring supports. These fixities work the same as supports and member-end fixities, but instead of adding an ‘Rthe user would define the degree of freedom as a ‘S’. So for instance, if you wish to add a vertical spring support, the user would add the fixity code “FSFRRR” – the second character would denote the Translation Y degree of freedom, so inputting that as an “S” means it is partially released in the Y direction. Nota, the RRR is entered as common practice as typically the rotations are also released.
spring supports in structural analysis software

Once the user enters an ‘Sin a particular direction, another input will appear to prompt the user to enter a Stiffness for that particular direction. per esempio. if the user enters a Vertical Spring (like the above example) an input for Y Stiffness Seleziona la casella etichettata. The stiffness input is entered as force/distance (kip/ft, kN / m, eccetera..) which essentially represents how much force is required to compress the spring by a given distance (piede, meter).

The spring stiffness (normally denoted as K) can be calculated in a few different ways (based on Hooke’s Law (F/displacement), or based on the material EA/L) or can be supplied by the manufacturer of the spring support.

Inclined Supports

If you have a support that is not parallel with the X-Z plane, you can add an inclined support. These supports are not fully fixed or pinned, but arerollersupports that are free to move in the rotated plane. The reaction results at inclined supports will be orthogonal to the rotation of the support. You must select a node before clicking on the inclined support button as shown.

To model an inclined support, go to the “supporti” menù, then click on the inclined support button. The Inclined Roller Support popup will appear, input the necessary data.


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